Merge pull request 'feat: systemd auto-start for ROS2 + dashboard on Orin boot (bd-1hyn)' (#732) from sl-perception/bd-1hyn-orin-autostart into main

Extends the bd-66hx serial protocol with two new Orin→ESP32 commands:
  CMD_OTA_CHECK  (0x10): triggers gitea_ota_check_now(), responds with
    TELEM_VERSION_INFO (0x84) for Balance and IO (current + available ver).
  CMD_OTA_UPDATE (0x11): uint8 target (0=balance, 1=io, 2=both) — triggers
    uart_ota_trigger() for IO or ota_self_trigger() for Balance.
    NACK with ERR_OTA_BUSY or ERR_OTA_NO_UPDATE on failure.
New telemetry: TELEM_OTA_STATUS (0x83, target+state+progress+err),
  TELEM_VERSION_INFO (0x84, target+current[16]+available[16]).
Wires OTA stack into app_main: ota_self_health_check on boot,
  gitea_ota_init + ota_display_init after peripherals ready.
CMakeLists updated with all OTA component dependencies.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/ota-release.yml

@@ -0,0 +1,162 @@
+# .gitea/workflows/ota-release.yml
+# Gitea Actions — ESP32 OTA firmware build & release (bd-9kod)
+#
+# Triggers on signed release tags:
+#   esp32-balance/vX.Y.Z  →  builds esp32s3/balance/   (ESP32-S3 Balance board)
+#   esp32-io/vX.Y.Z       →  builds esp32s3-io/         (ESP32-S3 IO board)
+#
+# Uses the official espressif/idf Docker image for reproducible builds.
+# Attaches <app>_<version>.bin + <app>_<version>.sha256 to the Gitea release.
+# The ESP32 Balance OTA system fetches the .bin from the release asset URL.
+
+name: OTA release — build & attach firmware
+
+on:
+  push:
+    tags:
+      - "esp32-balance/v*"
+      - "esp32-io/v*"
+
+permissions:
+  contents: write
+
+jobs:
+  build-and-release:
+    name: Build ${{ github.ref_name }}
+    runs-on: ubuntu-latest
+    container:
+      image: espressif/idf:v5.2.2
+      options: --user root
+
+    steps:
+      # ── 1. Checkout ───────────────────────────────────────────────────────────
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # ── 2. Resolve build target from tag ─────────────────────────────────────
+      # Tag format:  esp32-balance/v1.2.3  or  esp32-io/v1.2.3
+      - name: Resolve project from tag
+        id: proj
+        shell: bash
+        run: |
+          TAG="${GITHUB_REF_NAME}"
+          case "$TAG" in
+            esp32-balance/*)
+              DIR="esp32s3/balance"
+              APP="esp32s3_balance"
+              ;;
+            esp32-io/*)
+              DIR="esp32s3-io"
+              APP="esp32s3_io"
+              ;;
+            *)
+              echo "::error::Unrecognised tag prefix: ${TAG}"
+              exit 1
+              ;;
+          esac
+          VERSION="${TAG#*/}"
+          echo "dir=${DIR}"         >> "$GITHUB_OUTPUT"
+          echo "app=${APP}"         >> "$GITHUB_OUTPUT"
+          echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+          echo "tag=${TAG}"         >> "$GITHUB_OUTPUT"
+          echo "Build: ${APP} ${VERSION} from ${DIR}"
+
+      # ── 3. Build with ESP-IDF ─────────────────────────────────────────────────
+      - name: Build firmware (idf.py build)
+        shell: bash
+        run: |
+          . "${IDF_PATH}/export.sh"
+          cd "${{ steps.proj.outputs.dir }}"
+          idf.py build
+
+      # ── 4. Collect binary & generate checksum ────────────────────────────────
+      - name: Collect artifacts
+        id: art
+        shell: bash
+        run: |
+          APP="${{ steps.proj.outputs.app }}"
+          VER="${{ steps.proj.outputs.version }}"
+          BIN_SRC="${{ steps.proj.outputs.dir }}/build/${APP}.bin"
+          BIN_OUT="${APP}_${VER}.bin"
+          SHA_OUT="${APP}_${VER}.sha256"
+
+          cp "$BIN_SRC" "$BIN_OUT"
+          sha256sum "$BIN_OUT" > "$SHA_OUT"
+
+          echo "bin=${BIN_OUT}" >> "$GITHUB_OUTPUT"
+          echo "sha=${SHA_OUT}" >> "$GITHUB_OUTPUT"
+
+          echo "Binary:   ${BIN_OUT} ($(wc -c < "$BIN_OUT") bytes)"
+          echo "Checksum: $(cat "$SHA_OUT")"
+
+      # ── 5. Archive artifacts in CI workspace ─────────────────────────────────
+      - name: Upload build artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: firmware-${{ steps.proj.outputs.app }}-${{ steps.proj.outputs.version }}
+          path: |
+            ${{ steps.art.outputs.bin }}
+            ${{ steps.art.outputs.sha }}
+
+      # ── 6. Create Gitea release (if needed) & upload assets ──────────────────
+      # Uses GITHUB_TOKEN (auto-provided, contents:write from permissions block).
+      # URL-encodes the tag to handle the slash in esp32-balance/vX.Y.Z.
+      - name: Publish assets to Gitea release
+        shell: bash
+        env:
+          GITEA_URL: https://gitea.vayrette.com
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          TAG: ${{ steps.proj.outputs.tag }}
+          BIN: ${{ steps.art.outputs.bin }}
+          SHA: ${{ steps.art.outputs.sha }}
+        run: |
+          API="${GITEA_URL}/api/v1/repos/${REPO}"
+
+          # URL-encode the tag (slash in esp32-balance/vX.Y.Z must be escaped)
+          TAG_ENC=$(python3 -c "
+          import urllib.parse, sys
+          print(urllib.parse.quote(sys.argv[1], safe=''))
+          " "$TAG")
+
+          # Try to fetch an existing release for this tag
+          RELEASE=$(curl -sf \
+            -H "Authorization: token ${TOKEN}" \
+            "${API}/releases/tags/${TAG_ENC}") || true
+
+          # If no release yet, create it
+          if [ -z "$RELEASE" ]; then
+            echo "Creating release for tag: ${TAG}"
+            RELEASE=$(curl -sf \
+              -X POST \
+              -H "Authorization: token ${TOKEN}" \
+              -H "Content-Type: application/json" \
+              -d "$(python3 -c "
+          import json, sys
+          print(json.dumps({
+              'tag_name': sys.argv[1],
+              'name':     sys.argv[1],
+              'draft':    False,
+              'prerelease': False,
+          }))
+          " "$TAG")" \
+              "${API}/releases")
+          fi
+
+          RELEASE_ID=$(echo "$RELEASE" | python3 -c "
+          import sys, json; print(json.load(sys.stdin)['id'])
+          ")
+          echo "Release ID: ${RELEASE_ID}"
+
+          # Upload binary and checksum
+          for FILE in "$BIN" "$SHA"; do
+            FNAME=$(basename "$FILE")
+            echo "Uploading: ${FNAME}"
+            curl -sf \
+              -X POST \
+              -H "Authorization: token ${TOKEN}" \
+              -F "attachment=@${FILE}" \
+              "${API}/releases/${RELEASE_ID}/assets?name=${FNAME}"
+          done
+
+          echo "Published: ${BIN} + ${SHA} → release ${TAG}"

.pio/build/project.checksum

@@ -1 +1 @@
-8700a44a6597bcade0f371945c539630ba0e78b1
+ffc01fb580c81760bdda9a672fe1212be4578e3e

AUTONOMOUS_ARMING.md

@@ -0,0 +1,148 @@
+# Autonomous Arming (Issue #512)
+
+## Overview
+The robot can now be armed and operated autonomously from the Jetson without requiring an RC transmitter. The RC receiver (ELRS) is now optional and serves as an override/kill-switch rather than a requirement.
+
+## Arming Sources
+
+### Jetson Autonomous Arming
+- Command: `A\n` (single byte 'A' followed by newline)
+<<<<<<< HEAD
+- Sent via USB CDC to the ESP32 BALANCE firmware
+=======
+- Sent via USB Serial (CH343) to the ESP32-S3 firmware
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
+- Robot arms after ARMING_HOLD_MS (~500ms) safety hold period
+- Works even when RC is not connected or not armed
+
+### RC Arming (Optional Override)
+- Command: CH5 switch on ELRS transmitter
+- When RC is connected and armed, robot can be armed via RC
+- RC and Jetson can both request arming independently
+
+## Safety Features
+
+### Maintained from Original Design
+1. **Arming Hold Timer** — 500ms hold before motors enable (prevents accidental arming)
+2. **Tilt Safety** — Robot must be within ±10° level to arm
+3. **IMU Calibration** — Gyro must be calibrated before arming
+4. **Remote E-Stop Override** — `safety_remote_estop_active()` blocks all arming
+
+### New for Autonomous Operation
+1. **RC Kill Switch** (CH5 OFF when RC connected)
+   - Triggers emergency stop (motor cutoff) instead of disarm
+   - Allows Jetson-armed robots to remain armed when RC disconnects
+   - Maintains safety of kill switch for emergency situations
+
+2. **RC Failsafe**
+   - If RC signal is lost after being established, robot disarms (500ms timeout)
+   - Prevents runaway if RC connection drops during flight
+   - USB-only mode (no RC ever connected) is unaffected
+
+3. **Jetson Timeout** (200ms heartbeat)
+   - Jetson must send heartbeat (H command) every 500ms
+   - Prevents autonomous runaway if Jetson crashes/loses connection
+   - Handled by `jetson_cmd_is_active()` checks
+
+## Command Protocol
+
+<<<<<<< HEAD
+### From Jetson to ESP32 BALANCE (USB CDC)
+=======
+### From Jetson to ESP32-S3 (USB Serial (CH343))
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
+```
+A           — Request arm (triggers safety hold, then motors enable)
+D           — Request disarm (immediate motor stop)
+E           — Emergency stop (immediate motor cutoff, latched)
+Z           — Clear emergency stop latch
+H           — Heartbeat (refresh timeout timer, every 500ms)
+C<spd>,<str> — Drive command: speed, steer (also refreshes heartbeat)
+```
+
+<<<<<<< HEAD
+### From ESP32 BALANCE to Jetson (USB CDC)
+=======
+### From ESP32-S3 to Jetson (USB Serial (CH343))
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
+Motor commands are gated by `bal.state == BALANCE_ARMED`:
+- When ARMED: Motor commands sent every 20ms (50 Hz)
+- When DISARMED: Zero sent every 20ms (prevents ESC timeout)
+
+## Arming State Machine
+
+```
+DISARMED
+  ↓
+  +-- Jetson sends 'A' OR RC CH5 rises (with conditions met)
+      ↓
+      safety_arm_start() called
+      (arm hold timer starts)
+      ↓
+      Wait ARMING_HOLD_MS
+      ↓
+      safety_arm_ready() returns true
+      ↓
+      balance_arm() called
+      ARMED ← (motors now respond to commands)
+
+ARMED
+  ↓
+  +-- Jetson sends 'D' → balance_disarm()
+  +-- RC CH5 falls AND RC still alive → balance_disarm()
+  +-- RC signal lost (failsafe) → balance_disarm()
+  +-- Tilt fault detected → immediate motor stop
+  +-- RC kill switch (CH5 OFF) → emergency stop (not disarm)
+```
+
+## RC Override Priority
+
+When RC is connected and active:
+- **Steer channel**: Blended with Jetson via `mode_manager` (per active mode)
+- **Kill switch**: RC CH5 OFF triggers emergency stop (overrides everything)
+- **Failsafe**: RC signal loss triggers disarm (prevents runaway)
+
+When RC is disconnected:
+- Robot operates under Jetson commands alone
+- Emergency stop remains available via 'E' command from Jetson
+- No automatic mode change; mission continues autonomously
+
+## Testing Checklist
+
+- [ ] Jetson can arm robot without RC (send 'A' command)
+- [ ] Robot motors respond to Jetson drive commands when armed
+- [ ] Robot disarms on Jetson 'D' command
+- [ ] RC kill switch (CH5 OFF) triggers emergency stop without disarming
+- [ ] Robot can be re-armed after RC kill switch via Jetson 'A' command
+- [ ] RC failsafe still works (500ms signal loss = disarm)
+- [ ] Jetson heartbeat timeout works (500ms without H/C = motors zero)
+- [ ] Tilt fault still triggers immediate stop
+- [ ] IMU calibration required before arm
+- [ ] Arming hold timer (500ms) enforced
+
+## Migration from RC-Only
+
+### Old Workflow (ELRS-Required)
+1. Power on robot
+2. Arm via RC CH5
+3. Send speed/steer commands via RC
+4. Disarm via RC CH5
+
+### New Workflow (Autonomous)
+1. Power on robot
+2. Send heartbeat 'H' every 500ms from Jetson
+3. When ready to move, send 'A' command (wait 500ms)
+4. Send drive commands 'C<spd>,<str>' every ≤200ms
+5. When done, send 'D' command to disarm
+
+### New Workflow (RC + Autonomous Mixed)
+1. Power on robot, bring up RC
+2. Jetson sends heartbeat 'H'
+3. Arm via RC CH5 OR Jetson 'A' (both valid)
+4. Control via RC sticks OR Jetson drive commands (blended)
+5. Emergency kill: RC CH5 OFF (emergency stop) OR Jetson 'E'
+6. Disarm: RC CH5 OFF then ON, OR Jetson 'D'
+
+## References
+- Issue #512: Remove ELRS arm requirement
+- Files: `/src/main.c` (arming logic), `/lib/USB_CDC/src/usbd_cdc_if.c` (CDC commands)

CLAUDE.md

@@ -1,17 +1,36 @@
 # SaltyLab Firmware — Agent Playbook
 
 ## Project
-Self-balancing two-wheeled robot: STM32F722 flight controller, hoverboard hub motors, Jetson Nano for AI/SLAM.
+<<<<<<< HEAD
+**SAUL-TEE** — 4-wheel wagon (870×510×550 mm, 23 kg).
+Two ESP32-S3 boards + Jetson Orin via CAN. Full spec: `docs/SAUL-TEE-SYSTEM-REFERENCE.md`
+
+| Board | Role |
+|-------|------|
+| **ESP32-S3 BALANCE** | QMI8658 IMU, PID balance, CAN→VESC (L:68 / R:56), GC9A01 LCD (Waveshare Touch LCD 1.28) |
+| **ESP32-S3 IO** | TBS Crossfire RC, ELRS failover, BTS7960 motors, NFC/baro/ToF, WS2812 |
+| **Jetson Orin** | AI/SLAM, CANable2 USB→CAN, cmds 0x300–0x303, telemetry 0x400–0x401 |
+
+> **Legacy:** `src/` and `include/` = archived STM32 HAL — do not extend. New firmware in `esp32/`.
+=======
+Self-balancing two-wheeled robot: ESP32-S3 ESP32-S3 BALANCE, hoverboard hub motors, Jetson Orin Nano Super for AI/SLAM.
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 
 ## Team
 | Agent | Role | Focus |
 |-------|------|-------|
-| **sl-firmware** | Embedded Firmware Lead | STM32 HAL, USB CDC debugging, SPI/UART, PlatformIO, DFU bootloader |
+<<<<<<< HEAD
+| **sl-firmware** | Embedded Firmware Lead | ESP32-S3, ESP-IDF, QMI8658, CAN/UART protocol, BTS7960 |
+| **sl-controls** | Control Systems Engineer | PID tuning, IMU fusion, balance loop, safety |
+| **sl-perception** | Perception / SLAM Engineer | Jetson Orin, RealSense D435i, RPLIDAR, ROS2, Nav2 |
+=======
+| **sl-firmware** | Embedded Firmware Lead | ESP-IDF, USB Serial (CH343) debugging, SPI/UART, PlatformIO, DFU bootloader |
 | **sl-controls** | Control Systems Engineer | PID tuning, IMU sensor fusion, real-time control loops, safety systems |
-| **sl-perception** | Perception / SLAM Engineer | Jetson Nano, RealSense D435i, RPLIDAR, ROS2, Nav2 |
+| **sl-perception** | Perception / SLAM Engineer | Jetson Orin Nano Super, RealSense D435i, RPLIDAR, ROS2, Nav2 |
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 
 ## Status
-USB CDC TX bug resolved (PR #10 — DCache MPU non-cacheable region + IWDG ordering fix).
+USB Serial (CH343) TX bug resolved (PR #10 — DCache MPU non-cacheable region + IWDG ordering fix).
 
 ## Repo Structure
 - `projects/saltybot/SALTYLAB.md` — Design doc
@@ -29,11 +48,11 @@ USB CDC TX bug resolved (PR #10 — DCache MPU non-cacheable region + IWDG order
 | `saltyrover-dev` | Integration — rover variant |
 | `saltytank` | Stable — tracked tank variant |
 | `saltytank-dev` | Integration — tank variant |
-| `main` | Shared code only (IMU drivers, USB CDC, balance core, safety) |
+| `main` | Shared code only (IMU drivers, USB Serial (CH343), balance core, safety) |
 
 ### Rules
 - Agents branch FROM `<variant>-dev` and PR back TO `<variant>-dev`
-- Shared/infrastructure code (IMU drivers, USB CDC, balance core, safety) goes in `main`
+- Shared/infrastructure code (IMU drivers, USB Serial (CH343), balance core, safety) goes in `main`
 - Variant-specific code (motor topology, kinematics, config) goes in variant branches
 - Stable branches get promoted from `-dev` after review and hardware testing
 - **Current SaltyLab team** works against `saltylab-dev`

TEAM.md

@@ -1,12 +1,22 @@
 # SaltyLab — Ideal Team
 
 ## Project
-Self-balancing two-wheeled robot using a drone flight controller (STM32F722), hoverboard hub motors, and eventually a Jetson Nano for AI/SLAM.
+<<<<<<< HEAD
+**SAUL-TEE** — 4-wheel wagon (870×510×550 mm, 23 kg).
+Two ESP32-S3 boards (BALANCE + IO) + Jetson Orin. See `docs/SAUL-TEE-SYSTEM-REFERENCE.md`.
+
+## Current Status
+- **Hardware:** ESP32-S3 BALANCE (Waveshare Touch LCD 1.28, CH343 USB) + ESP32-S3 IO (bare devkit, JTAG USB)
+- **Firmware:** ESP-IDF/PlatformIO target; legacy `src/` STM32 HAL archived
+- **Comms:** UART 460800 baud inter-board; CANable2 USB→CAN for Orin; CAN 500 kbps to VESCs (L:68 / R:56)
+=======
+Self-balancing two-wheeled robot using a drone ESP32-S3 BALANCE (ESP32-S3), hoverboard hub motors, and eventually a Jetson Orin Nano Super for AI/SLAM.
 
 ## Current Status
 - **Hardware:** Assembled — FC, motors, ESC, IMU, battery, RC all on hand
-- **Firmware:** Balance PID + hoverboard ESC protocol written, but blocked by USB CDC bug
+- **Firmware:** Balance PID + hoverboard ESC protocol written, but blocked by USB Serial (CH343) bug
-- **Blocker:** USB CDC TX stops working when peripheral inits (SPI/UART/GPIO) are added alongside USB OTG FS — see `USB_CDC_BUG.md`
+- **Blocker:** USB Serial (CH343) TX stops working when peripheral inits (SPI/UART/GPIO) are added alongside USB on ESP32-S3 — see `legacy/stm32/USB_CDC_BUG.md` for historical context
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 
 ---
 
@@ -14,18 +24,30 @@ Self-balancing two-wheeled robot using a drone flight controller (STM32F722), ho
 
 ### 1. Embedded Firmware Engineer (Lead)
 **Must-have:**
-- Deep STM32 HAL experience (F7 series specifically)
+<<<<<<< HEAD
+- Deep ESP32 (Arduino/ESP-IDF) or STM32 HAL experience
 - USB OTG FS / CDC ACM debugging (TxState, endpoint management, DMA conflicts)
-- SPI + UART + USB coexistence on STM32
+- SPI + UART + USB coexistence on ESP32
-- PlatformIO or bare-metal STM32 toolchain
+- PlatformIO or bare-metal ESP32 toolchain
 - DFU bootloader implementation
+=======
+- Deep ESP-IDF experience (ESP32-S3 specifically)
+- USB Serial (CH343) / UART debugging on ESP32-S3
+- SPI + UART + USB coexistence on ESP32-S3
+- ESP-IDF / Arduino-ESP32 toolchain
+- OTA firmware update implementation
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 
 **Nice-to-have:**
-- Betaflight/iNav/ArduPilot codebase familiarity
+- ESP32-S3 peripheral coexistence (SPI + UART + USB)
 - PID control loop tuning for balance robots
 - FOC motor control (hoverboard ESC protocol)
 
-**Why:** The immediate blocker is a USB peripheral conflict. Need someone who's debugged STM32 USB issues before — this is not a software logic bug, it's a hardware peripheral interaction issue.
+<<<<<<< HEAD
+**Why:** The immediate blocker is a USB peripheral conflict. Need someone who's debugged STM32 USB issues before — ESP32 firmware for the balance loop and I/O needs to be written from scratch.
+=======
+**Why:** The immediate blocker is a USB peripheral conflict on ESP32-S3. Need someone who's debugged ESP32-S3 USB Serial (CH343) issues before — this is not a software logic bug, it's a hardware peripheral interaction issue.
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 
 ### 2. Control Systems / Robotics Engineer
 **Must-have:**
@@ -43,7 +65,7 @@ Self-balancing two-wheeled robot using a drone flight controller (STM32F722), ho
 
 ### 3. Perception / SLAM Engineer (Phase 2)
 **Must-have:**
-- Jetson Nano / NVIDIA Jetson platform
+- Jetson Orin Nano Super / NVIDIA Jetson platform
 - Intel RealSense D435i depth camera
 - RPLIDAR integration
 - SLAM (ORB-SLAM3, RTAB-Map, or similar)
@@ -54,19 +76,23 @@ Self-balancing two-wheeled robot using a drone flight controller (STM32F722), ho
 - Obstacle avoidance
 - Nav2 stack
 
-**Why:** Phase 2 goal is autonomous navigation. Jetson Nano with RealSense + RPLIDAR for indoor mapping and person following.
+**Why:** Phase 2 goal is autonomous navigation. Jetson Orin Nano Super with RealSense + RPLIDAR for indoor mapping and person following.
 
 ---
 
 ## Hardware Reference
 | Component | Details |
 |-----------|---------|
-| FC | MAMBA F722S (STM32F722RET6, MPU6000) |
+<<<<<<< HEAD
+| FC | ESP32 BALANCE (ESP32RET6, MPU6000) |
+=======
+| FC | ESP32-S3 BALANCE (ESP32-S3RET6, QMI8658) |
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 | Motors | 2x 8" pneumatic hoverboard hub motors |
 | ESC | Hoverboard ESC (EFeru FOC firmware) |
 | Battery | 36V pack |
 | RC | BetaFPV ELRS 2.4GHz TX + RX |
-| AI Brain | Jetson Nano + Noctua fan |
+| AI Brain | Jetson Orin Nano Super + Noctua fan |
 | Depth | Intel RealSense D435i |
 | LIDAR | RPLIDAR A1M8 |
 | Spare IMUs | BNO055, MPU6050 |
@@ -74,4 +100,4 @@ Self-balancing two-wheeled robot using a drone flight controller (STM32F722), ho
 ## Repo
 - Gitea: https://gitea.vayrette.com/seb/saltylab-firmware
 - Design doc: `projects/saltybot/SALTYLAB.md`
-- Bug doc: `USB_CDC_BUG.md`
+- Bug doc: `legacy/stm32/USB_CDC_BUG.md` (archived — STM32 era)

USB_CDC_BUG.md

@@ -1,44 +0,0 @@
-# USB CDC TX Bug — 2026-02-28
-
-## Problem
-Balance firmware produces no USB CDC output. Minimal "hello" test firmware works fine.
-
-## What Works
-- **Test firmware** (just sends `{"hello":N}` at 10Hz after 3s delay): **DATA FLOWS**
-- USB enumeration works in both cases (port appears as `/dev/cu.usbmodemSALTY0011`)
-- DFU reboot via RTC backup register works (Betaflight-proven pattern)
-
-## What Doesn't Work
-- **Balance firmware**: port opens, no data ever arrives
-- Tried: removing init transmit, 3s boot delay, TxState recovery, DTR detection, streaming flags
-- None of it helps
-
-## Key Difference Between Working & Broken
-- **Working test**: main.c only includes USB CDC headers, HAL, string, stdio
-- **Balance firmware**: includes icm42688.h, bmp280.h, balance.h, hoverboard.h, config.h, status.h
-- Balance firmware inits SPI1 (IMU), USART2 (hoverboard), GPIO (LEDs, buzzer)
-- Likely culprit: **peripheral init (SPI/UART/GPIO) is interfering with USB OTG FS**
-
-## Suspected Root Cause
-One of the additional peripheral inits (SPI1 for IMU, USART2 for hoverboard ESC, or GPIO for status LEDs) is likely conflicting with the USB OTG FS peripheral — either a clock conflict, GPIO pin conflict, or interrupt priority issue.
-
-## Hardware
-- MAMBA F722S FC (STM32F722RET6)
-- Betaflight target: DIAT-MAMBAF722_2022B
-- IMU: MPU6000 on SPI1 (PA4/PA5/PA6/PA7)
-- USB: OTG FS (PA11/PA12)
-- Hoverboard ESC: USART2 (PA2/PA3)
-- LEDs: PC14, PC15
-- Buzzer: PB2
-
-## Files
-- PlatformIO project: `~/Projects/saltylab-firmware/` on mbpm4 (192.168.87.40)
-- Working test: was in src/main.c (replaced with balance code)
-- Balance main.c backup: src/main.c.bak
-- CDC implementation: lib/USB_CDC/src/usbd_cdc_if.c
-
-## To Debug
-1. Add peripherals one at a time to the test firmware to find which one breaks CDC TX
-2. Check for GPIO pin conflicts with USB OTG FS (PA11/PA12)
-3. Check interrupt priorities — USB OTG FS IRQ might be getting starved
-4. Check if DCache (disabled via SCB_DisableDCache) is needed for USB DMA

android/build.gradle

@@ -0,0 +1,46 @@
+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+}
+
+android {
+    compileSdk 34
+    namespace 'com.saltylab.uwbtag'
+
+    defaultConfig {
+        applicationId "com.saltylab.uwbtag"
+        minSdk 26
+        targetSdk 34
+        versionCode 1
+        versionName "1.0"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
+
+    buildFeatures {
+        viewBinding true
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_17
+        targetCompatibility JavaVersion.VERSION_17
+    }
+
+    kotlinOptions {
+        jvmTarget = '17'
+    }
+}
+
+dependencies {
+    implementation 'androidx.core:core-ktx:1.12.0'
+    implementation 'androidx.appcompat:appcompat:1.6.1'
+    implementation 'com.google.android.material:material:1.11.0'
+    implementation 'androidx.recyclerview:recyclerview:1.3.2'
+    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.7.0'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
+    implementation 'com.google.code.gson:gson:2.10.1'
+}

android/src/main/AndroidManifest.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <!-- BLE permissions (API 31+) -->
+    <uses-permission android:name="android.permission.BLUETOOTH_SCAN"
+        android:usesPermissionFlags="neverForLocation" />
+    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
+    <uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />
+
+    <!-- Legacy BLE (API < 31) -->
+    <uses-permission android:name="android.permission.BLUETOOTH"
+        android:maxSdkVersion="30" />
+    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"
+        android:maxSdkVersion="30" />
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"
+        android:maxSdkVersion="30" />
+
+    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true" />
+
+    <application
+        android:allowBackup="true"
+        android:label="UWB Tag Config"
+        android:theme="@style/Theme.MaterialComponents.DayNight.DarkActionBar">
+
+        <activity
+            android:name=".UwbTagBleActivity"
+            android:exported="true"
+            android:launchMode="singleTop">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+    </application>
+
+</manifest>

android/src/main/kotlin/com/saltylab/uwbtag/UwbTagBleActivity.kt

@@ -0,0 +1,444 @@
+package com.saltylab.uwbtag
+
+import android.Manifest
+import android.annotation.SuppressLint
+import android.bluetooth.*
+import android.bluetooth.le.*
+import android.content.Context
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Button
+import android.widget.TextView
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.app.ActivityCompat
+import androidx.core.content.ContextCompat
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import com.google.android.material.card.MaterialCardView
+import com.google.android.material.switchmaterial.SwitchMaterial
+import com.google.android.material.textfield.TextInputEditText
+import com.google.gson.Gson
+import com.saltylab.uwbtag.databinding.ActivityUwbTagBleBinding
+import java.util.UUID
+
+// ---------------------------------------------------------------------------
+// GATT service / characteristic UUIDs
+// ---------------------------------------------------------------------------
+private val SERVICE_UUID     = UUID.fromString("12345678-1234-5678-1234-56789abcdef0")
+private val CHAR_CONFIG_UUID = UUID.fromString("12345678-1234-5678-1234-56789abcdef1") // read/write JSON config
+private val CHAR_STATUS_UUID = UUID.fromString("12345678-1234-5678-1234-56789abcdef2") // notify: tag status string
+private val CHAR_BATT_UUID   = UUID.fromString("12345678-1234-5678-1234-56789abcdef3") // notify: battery %
+private val CCCD_UUID        = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb")
+
+// BLE scan timeout
+private const val SCAN_TIMEOUT_MS = 15_000L
+
+// Permissions request code
+private const val REQ_PERMISSIONS = 1001
+
+// ---------------------------------------------------------------------------
+// Data model
+// ---------------------------------------------------------------------------
+data class TagConfig(
+    val tag_name: String = "UWB_TAG_0001",
+    val sleep_timeout_s: Int = 300,
+    val display_brightness: Int = 50,
+    val uwb_channel: Int = 9,
+    val ranging_interval_ms: Int = 100,
+    val battery_report: Boolean = true
+)
+
+data class ScannedDevice(
+    val name: String,
+    val address: String,
+    var rssi: Int,
+    val device: BluetoothDevice
+)
+
+// ---------------------------------------------------------------------------
+// RecyclerView adapter for scanned devices
+// ---------------------------------------------------------------------------
+class DeviceAdapter(
+    private val onConnect: (ScannedDevice) -> Unit
+) : RecyclerView.Adapter<DeviceAdapter.VH>() {
+
+    private val items = mutableListOf<ScannedDevice>()
+
+    fun update(device: ScannedDevice) {
+        val idx = items.indexOfFirst { it.address == device.address }
+        if (idx >= 0) {
+            items[idx] = device
+            notifyItemChanged(idx)
+        } else {
+            items.add(device)
+            notifyItemInserted(items.size - 1)
+        }
+    }
+
+    fun clear() {
+        items.clear()
+        notifyDataSetChanged()
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): VH {
+        val view = LayoutInflater.from(parent.context)
+            .inflate(R.layout.item_ble_device, parent, false)
+        return VH(view)
+    }
+
+    override fun onBindViewHolder(holder: VH, position: Int) = holder.bind(items[position])
+    override fun getItemCount() = items.size
+
+    inner class VH(view: View) : RecyclerView.ViewHolder(view) {
+        private val tvName    = view.findViewById<TextView>(R.id.tvDeviceName)
+        private val tvAddress = view.findViewById<TextView>(R.id.tvDeviceAddress)
+        private val tvRssi    = view.findViewById<TextView>(R.id.tvRssi)
+        private val btnConn   = view.findViewById<Button>(R.id.btnConnect)
+
+        fun bind(item: ScannedDevice) {
+            tvName.text    = item.name
+            tvAddress.text = item.address
+            tvRssi.text    = "${item.rssi} dBm"
+            btnConn.setOnClickListener { onConnect(item) }
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Activity
+// ---------------------------------------------------------------------------
+@SuppressLint("MissingPermission") // permissions checked at runtime before any BLE call
+class UwbTagBleActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityUwbTagBleBinding
+    private val gson = Gson()
+    private val mainHandler = Handler(Looper.getMainLooper())
+
+    // BLE
+    private val btManager by lazy { getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager }
+    private val btAdapter by lazy { btManager.adapter }
+    private var bleScanner: BluetoothLeScanner? = null
+    private var gatt: BluetoothGatt? = null
+    private var configChar: BluetoothGattCharacteristic? = null
+    private var statusChar: BluetoothGattCharacteristic? = null
+    private var battChar: BluetoothGattCharacteristic? = null
+    private var isScanning = false
+
+    private val deviceAdapter = DeviceAdapter(onConnect = ::connectToDevice)
+
+    // ---------------------------------------------------------------------------
+    // Lifecycle
+    // ---------------------------------------------------------------------------
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityUwbTagBleBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        setSupportActionBar(binding.toolbar)
+
+        binding.rvDevices.layoutManager = LinearLayoutManager(this)
+        binding.rvDevices.adapter = deviceAdapter
+
+        binding.btnScan.setOnClickListener {
+            if (isScanning) stopScan() else startScanIfPermitted()
+        }
+        binding.btnDisconnect.setOnClickListener { disconnectGatt() }
+        binding.btnReadConfig.setOnClickListener { readConfig() }
+        binding.btnWriteConfig.setOnClickListener { writeConfig() }
+
+        requestBlePermissions()
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        stopScan()
+        disconnectGatt()
+    }
+
+    // ---------------------------------------------------------------------------
+    // Permissions
+    // ---------------------------------------------------------------------------
+    private fun requestBlePermissions() {
+        val needed = mutableListOf<String>()
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            if (!hasPermission(Manifest.permission.BLUETOOTH_SCAN))
+                needed += Manifest.permission.BLUETOOTH_SCAN
+            if (!hasPermission(Manifest.permission.BLUETOOTH_CONNECT))
+                needed += Manifest.permission.BLUETOOTH_CONNECT
+        } else {
+            if (!hasPermission(Manifest.permission.ACCESS_FINE_LOCATION))
+                needed += Manifest.permission.ACCESS_FINE_LOCATION
+        }
+        if (needed.isNotEmpty()) {
+            ActivityCompat.requestPermissions(this, needed.toTypedArray(), REQ_PERMISSIONS)
+        }
+    }
+
+    private fun hasPermission(perm: String) =
+        ContextCompat.checkSelfPermission(this, perm) == PackageManager.PERMISSION_GRANTED
+
+    override fun onRequestPermissionsResult(
+        requestCode: Int, permissions: Array<out String>, grantResults: IntArray
+    ) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+        if (requestCode == REQ_PERMISSIONS &&
+            grantResults.any { it != PackageManager.PERMISSION_GRANTED }) {
+            toast("BLE permissions required")
+        }
+    }
+
+    // ---------------------------------------------------------------------------
+    // BLE Scan
+    // ---------------------------------------------------------------------------
+    private fun startScanIfPermitted() {
+        if (btAdapter?.isEnabled != true) { toast("Bluetooth is off"); return }
+        bleScanner = btAdapter.bluetoothLeScanner
+        val filter = ScanFilter.Builder()
+            .setDeviceNamePattern("UWB_TAG_.*".toRegex().toPattern())
+            .build()
+        val settings = ScanSettings.Builder()
+            .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
+            .build()
+        deviceAdapter.clear()
+        bleScanner?.startScan(listOf(filter), settings, scanCallback)
+        isScanning = true
+        binding.btnScan.text = "Stop"
+        binding.tvScanStatus.text = "Scanning…"
+        mainHandler.postDelayed({ stopScan() }, SCAN_TIMEOUT_MS)
+    }
+
+    private fun stopScan() {
+        bleScanner?.stopScan(scanCallback)
+        isScanning = false
+        binding.btnScan.text = "Scan"
+        binding.tvScanStatus.text = "Scan stopped"
+    }
+
+    private val scanCallback = object : ScanCallback() {
+        override fun onScanResult(callbackType: Int, result: ScanResult) {
+            val name = result.device.name ?: return
+            if (!name.startsWith("UWB_TAG_")) return
+            val dev = ScannedDevice(
+                name    = name,
+                address = result.device.address,
+                rssi    = result.rssi,
+                device  = result.device
+            )
+            mainHandler.post { deviceAdapter.update(dev) }
+        }
+
+        override fun onScanFailed(errorCode: Int) {
+            mainHandler.post {
+                binding.tvScanStatus.text = "Scan failed (code $errorCode)"
+                isScanning = false
+                binding.btnScan.text = "Scan"
+            }
+        }
+    }
+
+    // ---------------------------------------------------------------------------
+    // GATT Connection
+    // ---------------------------------------------------------------------------
+    private fun connectToDevice(scanned: ScannedDevice) {
+        stopScan()
+        binding.tvScanStatus.text = "Connecting to ${scanned.name}…"
+        gatt = scanned.device.connectGatt(this, false, gattCallback, BluetoothDevice.TRANSPORT_LE)
+    }
+
+    private fun disconnectGatt() {
+        gatt?.disconnect()
+        gatt?.close()
+        gatt = null
+        configChar = null
+        statusChar = null
+        battChar = null
+        mainHandler.post {
+            binding.cardConfig.visibility = View.GONE
+            binding.tvScanStatus.text = "Disconnected"
+        }
+    }
+
+    private val gattCallback = object : BluetoothGattCallback() {
+
+        override fun onConnectionStateChange(g: BluetoothGatt, status: Int, newState: Int) {
+            when (newState) {
+                BluetoothProfile.STATE_CONNECTED -> {
+                    mainHandler.post { binding.tvScanStatus.text = "Connected — discovering services…" }
+                    g.discoverServices()
+                }
+                BluetoothProfile.STATE_DISCONNECTED -> {
+                    mainHandler.post {
+                        binding.cardConfig.visibility = View.GONE
+                        binding.tvScanStatus.text = "Disconnected"
+                        toast("Tag disconnected")
+                    }
+                    gatt?.close()
+                    gatt = null
+                }
+            }
+        }
+
+        override fun onServicesDiscovered(g: BluetoothGatt, status: Int) {
+            if (status != BluetoothGatt.GATT_SUCCESS) {
+                mainHandler.post { toast("Service discovery failed") }
+                return
+            }
+            val service = g.getService(SERVICE_UUID)
+            if (service == null) {
+                mainHandler.post { toast("UWB config service not found on tag") }
+                return
+            }
+            configChar = service.getCharacteristic(CHAR_CONFIG_UUID)
+            statusChar = service.getCharacteristic(CHAR_STATUS_UUID)
+            battChar   = service.getCharacteristic(CHAR_BATT_UUID)
+
+            // Subscribe to status notifications
+            statusChar?.let { enableNotifications(g, it) }
+            battChar?.let   { enableNotifications(g, it) }
+
+            // Initial config read
+            configChar?.let { g.readCharacteristic(it) }
+
+            mainHandler.post {
+                val devName = g.device.name ?: g.device.address
+                binding.tvConnectedName.text = "Connected: $devName"
+                binding.cardConfig.visibility = View.VISIBLE
+                binding.tvScanStatus.text = "Connected to $devName"
+            }
+        }
+
+        override fun onCharacteristicRead(
+            g: BluetoothGatt,
+            characteristic: BluetoothGattCharacteristic,
+            status: Int
+        ) {
+            if (status != BluetoothGatt.GATT_SUCCESS) return
+            if (characteristic.uuid == CHAR_CONFIG_UUID) {
+                val json = characteristic.value?.toString(Charsets.UTF_8) ?: return
+                val cfg = runCatching { gson.fromJson(json, TagConfig::class.java) }.getOrNull() ?: return
+                mainHandler.post { populateFields(cfg) }
+            }
+        }
+
+        // API 33+ callback
+        override fun onCharacteristicRead(
+            g: BluetoothGatt,
+            characteristic: BluetoothGattCharacteristic,
+            value: ByteArray,
+            status: Int
+        ) {
+            if (status != BluetoothGatt.GATT_SUCCESS) return
+            if (characteristic.uuid == CHAR_CONFIG_UUID) {
+                val json = value.toString(Charsets.UTF_8)
+                val cfg = runCatching { gson.fromJson(json, TagConfig::class.java) }.getOrNull() ?: return
+                mainHandler.post { populateFields(cfg) }
+            }
+        }
+
+        override fun onCharacteristicWrite(
+            g: BluetoothGatt,
+            characteristic: BluetoothGattCharacteristic,
+            status: Int
+        ) {
+            val msg = if (status == BluetoothGatt.GATT_SUCCESS) "Config written" else "Write failed ($status)"
+            mainHandler.post { toast(msg) }
+        }
+
+        override fun onCharacteristicChanged(
+            g: BluetoothGatt,
+            characteristic: BluetoothGattCharacteristic
+        ) {
+            val value = characteristic.value ?: return
+            handleNotification(characteristic.uuid, value)
+        }
+
+        // API 33+ callback
+        override fun onCharacteristicChanged(
+            g: BluetoothGatt,
+            characteristic: BluetoothGattCharacteristic,
+            value: ByteArray
+        ) {
+            handleNotification(characteristic.uuid, value)
+        }
+    }
+
+    // ---------------------------------------------------------------------------
+    // Notification helpers
+    // ---------------------------------------------------------------------------
+    private fun enableNotifications(g: BluetoothGatt, char: BluetoothGattCharacteristic) {
+        g.setCharacteristicNotification(char, true)
+        val descriptor = char.getDescriptor(CCCD_UUID) ?: return
+        descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
+        g.writeDescriptor(descriptor)
+    }
+
+    private fun handleNotification(uuid: UUID, value: ByteArray) {
+        val text = value.toString(Charsets.UTF_8)
+        mainHandler.post {
+            when (uuid) {
+                CHAR_STATUS_UUID -> binding.tvTagStatus.text = "Status: $text"
+                CHAR_BATT_UUID   -> {
+                    val pct = text.toIntOrNull() ?: return@post
+                    binding.tvTagStatus.text = binding.tvTagStatus.text.toString()
+                        .replace(Regex("\\| Batt:.*"), "")
+                        .trimEnd() + " | Batt: $pct%"
+                }
+            }
+        }
+    }
+
+    // ---------------------------------------------------------------------------
+    // Config read / write
+    // ---------------------------------------------------------------------------
+    private fun readConfig() {
+        val g = gatt ?: run { toast("Not connected"); return }
+        val c = configChar ?: run { toast("Config char not found"); return }
+        g.readCharacteristic(c)
+    }
+
+    private fun writeConfig() {
+        val g = gatt ?: run { toast("Not connected"); return }
+        val c = configChar ?: run { toast("Config char not found"); return }
+        val cfg = buildConfigFromFields()
+        val json = gson.toJson(cfg)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            g.writeCharacteristic(c, json.toByteArray(Charsets.UTF_8),
+                BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT)
+        } else {
+            @Suppress("DEPRECATION")
+            c.value = json.toByteArray(Charsets.UTF_8)
+            @Suppress("DEPRECATION")
+            g.writeCharacteristic(c)
+        }
+    }
+
+    // ---------------------------------------------------------------------------
+    // UI helpers
+    // ---------------------------------------------------------------------------
+    private fun populateFields(cfg: TagConfig) {
+        binding.etTagName.setText(cfg.tag_name)
+        binding.etSleepTimeout.setText(cfg.sleep_timeout_s.toString())
+        binding.etBrightness.setText(cfg.display_brightness.toString())
+        binding.etUwbChannel.setText(cfg.uwb_channel.toString())
+        binding.etRangingInterval.setText(cfg.ranging_interval_ms.toString())
+        binding.switchBatteryReport.isChecked = cfg.battery_report
+    }
+
+    private fun buildConfigFromFields() = TagConfig(
+        tag_name           = binding.etTagName.text?.toString() ?: "UWB_TAG_0001",
+        sleep_timeout_s    = binding.etSleepTimeout.text?.toString()?.toIntOrNull() ?: 300,
+        display_brightness = binding.etBrightness.text?.toString()?.toIntOrNull() ?: 50,
+        uwb_channel        = binding.etUwbChannel.text?.toString()?.toIntOrNull() ?: 9,
+        ranging_interval_ms = binding.etRangingInterval.text?.toString()?.toIntOrNull() ?: 100,
+        battery_report     = binding.switchBatteryReport.isChecked
+    )
+
+    private fun toast(msg: String) =
+        Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
+}

android/src/main/res/layout/activity_uwb_tag_ble.xml

@@ -0,0 +1,238 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <androidx.appcompat.widget.Toolbar
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
+        android:layout_height="?attr/actionBarSize"
+        android:background="?attr/colorPrimary"
+        android:elevation="4dp"
+        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
+        app:title="UWB Tag BLE Config" />
+
+    <!-- Scan controls -->
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:padding="12dp"
+        android:gravity="center_vertical">
+
+        <Button
+            android:id="@+id/btnScan"
+            style="@style/Widget.MaterialComponents.Button"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Scan" />
+
+        <TextView
+            android:id="@+id/tvScanStatus"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:layout_marginStart="12dp"
+            android:text="Tap Scan to find UWB tags"
+            android:textAppearance="@style/TextAppearance.MaterialComponents.Body2" />
+
+    </LinearLayout>
+
+    <!-- Scan results list -->
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:paddingHorizontal="12dp"
+        android:text="Nearby Tags"
+        android:textAppearance="@style/TextAppearance.MaterialComponents.Subtitle1"
+        android:textStyle="bold" />
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/rvDevices"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:padding="8dp"
+        android:clipToPadding="false" />
+
+    <!-- Connected device config panel -->
+    <com.google.android.material.card.MaterialCardView
+        android:id="@+id/cardConfig"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_margin="8dp"
+        android:visibility="gone"
+        app:cardElevation="4dp">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="12dp">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:gravity="center_vertical">
+
+                <TextView
+                    android:id="@+id/tvConnectedName"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:text="Connected: —"
+                    android:textAppearance="@style/TextAppearance.MaterialComponents.Subtitle1"
+                    android:textStyle="bold" />
+
+                <Button
+                    android:id="@+id/btnDisconnect"
+                    style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Disconnect" />
+
+            </LinearLayout>
+
+            <!-- tag_name -->
+            <com.google.android.material.textfield.TextInputLayout
+                style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:hint="Tag Name">
+                <com.google.android.material.textfield.TextInputEditText
+                    android:id="@+id/etTagName"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:inputType="text" />
+            </com.google.android.material.textfield.TextInputLayout>
+
+            <!-- sleep_timeout_s and uwb_channel (row) -->
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:layout_marginTop="4dp">
+
+                <com.google.android.material.textfield.TextInputLayout
+                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginEnd="4dp"
+                    android:hint="Sleep Timeout (s)">
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/etSleepTimeout"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:inputType="number" />
+                </com.google.android.material.textfield.TextInputLayout>
+
+                <com.google.android.material.textfield.TextInputLayout
+                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginStart="4dp"
+                    android:hint="UWB Channel">
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/etUwbChannel"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:inputType="number" />
+                </com.google.android.material.textfield.TextInputLayout>
+
+            </LinearLayout>
+
+            <!-- display_brightness and ranging_interval_ms (row) -->
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:layout_marginTop="4dp">
+
+                <com.google.android.material.textfield.TextInputLayout
+                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginEnd="4dp"
+                    android:hint="Brightness (0-100)">
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/etBrightness"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:inputType="number" />
+                </com.google.android.material.textfield.TextInputLayout>
+
+                <com.google.android.material.textfield.TextInputLayout
+                    style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginStart="4dp"
+                    android:hint="Ranging Interval (ms)">
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:id="@+id/etRangingInterval"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:inputType="number" />
+                </com.google.android.material.textfield.TextInputLayout>
+
+            </LinearLayout>
+
+            <!-- battery_report toggle -->
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switchBatteryReport"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:text="Battery Reporting" />
+
+            <!-- Action buttons -->
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:layout_marginTop="8dp">
+
+                <Button
+                    android:id="@+id/btnReadConfig"
+                    style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginEnd="4dp"
+                    android:text="Read" />
+
+                <Button
+                    android:id="@+id/btnWriteConfig"
+                    style="@style/Widget.MaterialComponents.Button"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:layout_marginStart="4dp"
+                    android:text="Write" />
+
+            </LinearLayout>
+
+            <!-- Status notifications from tag -->
+            <TextView
+                android:id="@+id/tvTagStatus"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:background="#1A000000"
+                android:fontFamily="monospace"
+                android:padding="8dp"
+                android:text="Tag status: —"
+                android:textAppearance="@style/TextAppearance.MaterialComponents.Caption" />
+
+        </LinearLayout>
+
+    </com.google.android.material.card.MaterialCardView>
+
+</LinearLayout>

android/src/main/res/layout/item_ble_device.xml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="utf-8"?>
+<com.google.android.material.card.MaterialCardView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_margin="4dp"
+    app:cardElevation="2dp"
+    android:clickable="true"
+    android:focusable="true">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:padding="12dp"
+        android:gravity="center_vertical">
+
+        <LinearLayout
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:orientation="vertical">
+
+            <TextView
+                android:id="@+id/tvDeviceName"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="UWB_TAG_XXXX"
+                android:textAppearance="@style/TextAppearance.MaterialComponents.Subtitle2"
+                android:textStyle="bold" />
+
+            <TextView
+                android:id="@+id/tvDeviceAddress"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="XX:XX:XX:XX:XX:XX"
+                android:textAppearance="@style/TextAppearance.MaterialComponents.Caption" />
+
+        </LinearLayout>
+
+        <TextView
+            android:id="@+id/tvRssi"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="-70 dBm"
+            android:textAppearance="@style/TextAppearance.MaterialComponents.Caption"
+            android:textColor="?attr/colorSecondary" />
+
+        <Button
+            android:id="@+id/btnConnect"
+            style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:text="Connect" />
+
+    </LinearLayout>
+
+</com.google.android.material.card.MaterialCardView>

cad/assembly.scad

@@ -0,0 +1,118 @@
+// ============================================
+// SaltyLab — Full Assembly Visualization
+// Shows all parts in position on 2020 spine
+// ============================================
+include <dimensions.scad>
+
+// Spine height
+spine_h = 500;
+
+// Component heights (center of each mount on spine)
+h_motor = 0;
+h_battery = 50;
+h_esc = 100;
+h_fc = 170;
+h_jetson = 250;
+h_realsense = 350;
+h_lidar = 430;
+
+// Colors for visualization
+module spine() {
+    color("silver")
+        translate([-extrusion_w/2, -extrusion_w/2, 0])
+            cube([extrusion_w, extrusion_w, spine_h]);
+}
+
+module wheel(side) {
+    color("DimGray")
+        translate([side * 140, 0, 0])
+            rotate([0, 90, 0])
+                cylinder(d=200, h=50, center=true, $fn=60);
+}
+
+// --- Assembly ---
+
+// Spine
+spine();
+
+// Wheels
+wheel(-1);
+wheel(1);
+
+// Motor mount plate (at base)
+color("DodgerBlue", 0.7)
+    translate([0, 0, h_motor])
+        import("motor_mount_plate.stl");
+
+// Battery shelf
+color("OrangeRed", 0.7)
+    translate([0, 0, h_battery])
+        rotate([0, 0, 0])
+            cube([180, 80, 40], center=true);
+
+// ESC
+color("Green", 0.7)
+    translate([0, 0, h_esc])
+        cube([80, 50, 15], center=true);
+
+// FC (tiny!)
+color("Purple", 0.9)
+    translate([0, 0, h_fc])
+        cube([36, 36, 5], center=true);
+
+// Jetson Orin Nano Super
+color("LimeGreen", 0.7)
+    translate([0, 0, h_jetson])
+        cube([100, 80, 29], center=true);
+
+// RealSense D435i
+color("Gray", 0.8)
+    translate([0, -40, h_realsense])
+        cube([90, 25, 25], center=true);
+
+// RPLIDAR A1
+color("Cyan", 0.7)
+    translate([0, 0, h_lidar])
+        cylinder(d=70, h=41, center=true, $fn=40);
+
+// Kill switch (accessible on front)
+color("Red")
+    translate([0, -60, h_esc + 30])
+        cylinder(d=22, h=10, $fn=30);
+
+// LED ring
+color("White", 0.3)
+    translate([0, 0, h_jetson - 20])
+        difference() {
+            cylinder(d=120, h=15, $fn=60);
+            translate([0, 0, -1])
+                cylinder(d=110, h=17, $fn=60);
+        }
+
+// Bumpers
+color("Orange", 0.5) {
+    translate([0, -75, 25])
+        cube([350, 30, 50], center=true);
+    translate([0, 75, 25])
+        cube([350, 30, 50], center=true);
+}
+
+// Handle (top)
+color("Yellow", 0.7)
+    translate([0, 0, spine_h + 10])
+        cube([100, 20, 25], center=true);
+
+// Tether point
+color("Red", 0.8)
+    translate([0, 0, spine_h - 20]) {
+        difference() {
+            cylinder(d=30, h=8, $fn=30);
+            translate([0, 0, -1])
+                cylinder(d=15, h=10, $fn=30);
+        }
+    }
+
+echo("=== SaltyLab Assembly ===");
+echo(str("Total height: ", spine_h + 30, "mm"));
+echo(str("Width (axle-axle): ", 280 + 50*2, "mm"));
+echo(str("Depth: ~", 150, "mm"));

cad/battery_shelf.scad

@@ -0,0 +1,77 @@
+// ============================================
+// SaltyLab — Battery Shelf
+// 200×100×40mm PETG
+// Holds 36V battery pack low on the frame
+// Mounts to 2020 extrusion spine
+// ============================================
+include <dimensions.scad>
+
+shelf_w = 200;
+shelf_d = 100;
+shelf_h = 40;
+floor_h = 3;     // Bottom plate
+
+// Battery pocket (with tolerance)
+pocket_w = batt_w + tol*2;
+pocket_d = batt_d + tol*2;
+pocket_h = batt_h + 5;  // Slightly taller than battery
+
+// Velcro strap slots
+strap_w = 25;
+strap_h = 3;
+
+module battery_shelf() {
+    difference() {
+        union() {
+            // Floor
+            translate([-shelf_w/2, -shelf_d/2, 0])
+                cube([shelf_w, shelf_d, floor_h]);
+            
+            // Walls (3 sides — front open for wires)
+            // Left wall
+            translate([-shelf_w/2, -shelf_d/2, 0])
+                cube([wall, shelf_d, shelf_h]);
+            // Right wall
+            translate([shelf_w/2 - wall, -shelf_d/2, 0])
+                cube([wall, shelf_d, shelf_h]);
+            // Back wall
+            translate([-shelf_w/2, shelf_d/2 - wall, 0])
+                cube([shelf_w, wall, shelf_h]);
+            
+            // Front lip (low, keeps battery from sliding out)
+            translate([-shelf_w/2, -shelf_d/2, 0])
+                cube([shelf_w, wall, 10]);
+            
+            // 2020 extrusion mount tabs (top of back wall)
+            for (x = [-30, 30]) {
+                translate([x - 10, shelf_d/2 - wall, shelf_h - 15])
+                    cube([20, wall + 10, 15]);
+            }
+        }
+        
+        // Extrusion bolt holes (M5) through back mount tabs
+        for (x = [-30, 30]) {
+            translate([x, shelf_d/2 + 5, shelf_h - 7.5])
+                rotate([90, 0, 0])
+                    cylinder(d=m5_clear, h=wall + 15, $fn=30);
+        }
+        
+        // Velcro strap slots (2x through floor for securing battery)
+        for (x = [-50, 50]) {
+            translate([x - strap_w/2, -20, -1])
+                cube([strap_w, strap_h, floor_h + 2]);
+        }
+        
+        // Weight reduction holes in floor
+        for (x = [-30, 30]) {
+            translate([x, 0, -1])
+                cylinder(d=20, h=floor_h + 2, $fn=30);
+        }
+        
+        // Wire routing slot (front wall, centered)
+        translate([-20, -shelf_d/2 - 1, floor_h])
+            cube([40, wall + 2, 15]);
+    }
+}
+
+battery_shelf();

cad/bumper.scad

@@ -0,0 +1,75 @@
+// ============================================
+// SaltyLab — Bumper (Front/Rear)
+// 350×50×30mm TPU
+// Absorbs falls, protects frame and floor
+// ============================================
+include <dimensions.scad>
+
+bumper_w = 350;
+bumper_h = 50;
+bumper_d = 30;
+bumper_wall = 2.5;
+
+// Honeycomb crush structure for energy absorption
+hex_size = 8;
+hex_wall = 1.2;
+
+module honeycomb_cell(size, height) {
+    difference() {
+        cylinder(d=size, h=height, $fn=6);
+        translate([0, 0, -1])
+            cylinder(d=size - hex_wall*2, h=height + 2, $fn=6);
+    }
+}
+
+module bumper() {
+    difference() {
+        union() {
+            // Outer shell (curved front face)
+            hull() {
+                translate([-bumper_w/2, 0, 0])
+                    cube([bumper_w, 1, bumper_h]);
+                translate([-bumper_w/2 + 10, bumper_d - 5, 5])
+                    cube([bumper_w - 20, 1, bumper_h - 10]);
+            }
+        }
+        
+        // Hollow interior (leave outer shell)
+        hull() {
+            translate([-bumper_w/2 + bumper_wall, bumper_wall, bumper_wall])
+                cube([bumper_w - bumper_wall*2, 1, bumper_h - bumper_wall*2]);
+            translate([-bumper_w/2 + 10 + bumper_wall, bumper_d - 5 - bumper_wall, 5 + bumper_wall])
+                cube([bumper_w - 20 - bumper_wall*2, 1, bumper_h - 10 - bumper_wall*2]);
+        }
+        
+        // Mounting bolt holes (M5, through back face, 4 points)
+        for (x = [-120, -40, 40, 120]) {
+            translate([x, -1, bumper_h/2])
+                rotate([-90, 0, 0])
+                    cylinder(d=m5_clear, h=10, $fn=25);
+        }
+    }
+    
+    // Internal honeycomb ribs for crush absorption
+    intersection() {
+        // Bound to bumper volume
+        hull() {
+            translate([-bumper_w/2 + bumper_wall, bumper_wall, bumper_wall])
+                cube([bumper_w - bumper_wall*2, 1, bumper_h - bumper_wall*2]);
+            translate([-bumper_w/2 + 15, bumper_d - 8, 8])
+                cube([bumper_w - 30, 1, bumper_h - 16]);
+        }
+        
+        // Honeycomb grid
+        for (x = [-170:hex_size*1.5:170]) {
+            for (z = [0:hex_size*1.3:60]) {
+                offset_x = (floor(z / (hex_size*1.3)) % 2) * hex_size * 0.75;
+                translate([x + offset_x, 0, z])
+                    rotate([-90, 0, 0])
+                        honeycomb_cell(hex_size, bumper_d);
+            }
+        }
+    }
+}
+
+bumper();

cad/dimensions.scad

@@ -0,0 +1,73 @@
+// ============================================
+// SaltyLab — Common Dimensions & Constants
+// ============================================
+
+// --- 2020 Aluminum Extrusion ---
+extrusion_w = 20;
+extrusion_slot = 6;     // T-slot width
+extrusion_bore = 5;     // Center bore M5
+
+// --- Hub Motors (8" hoverboard) ---
+motor_axle_dia = 12;
+motor_axle_len = 45;
+motor_axle_flat = 10;   // Flat-to-flat if D-shaft
+motor_body_dia = 200;   // ~8 inches
+motor_bolt_circle = 0;  // Axle-only mount (clamp style)
+
+// --- Drone FC (30.5mm standard) ---
+fc_hole_spacing = 25.5;  // GEP-F722 AIO v2 (not standard 30.5!)
+fc_hole_dia = 3.2;      // M3 clearance
+fc_board_size = 36;      // Typical FC PCB
+fc_standoff_h = 5;       // Rubber standoff height
+
+// --- Jetson Orin Nano Super ---
+jetson_w = 100;
+jetson_d = 80;
+jetson_h = 29;           // With heatsink
+jetson_hole_x = 86;      // Mounting hole spacing X
+jetson_hole_y = 58;      // Mounting hole spacing Y
+jetson_hole_dia = 2.7;   // M2.5 clearance
+
+// --- RealSense D435i ---
+rs_w = 90;
+rs_d = 25;
+rs_h = 25;
+rs_tripod_offset = 0;    // 1/4-20 centered bottom
+rs_mount_dia = 6.5;      // 1/4-20 clearance
+
+// --- RPLIDAR A1 ---
+lidar_dia = 70;
+lidar_h = 41;
+lidar_mount_circle = 67; // Bolt circle diameter
+lidar_hole_count = 4;
+lidar_hole_dia = 2.7;    // M2.5
+
+// --- Kill Switch (22mm panel mount) ---
+kill_sw_dia = 22;
+kill_sw_depth = 35;      // Behind-panel depth
+
+// --- Battery (typical 36V hoverboard pack) ---
+batt_w = 180;
+batt_d = 80;
+batt_h = 40;
+
+// --- Hoverboard ESC ---
+esc_w = 80;
+esc_d = 50;
+esc_h = 15;
+
+// --- ESP32-C3 (typical dev board) ---
+esp_w = 25;
+esp_d = 18;
+esp_h = 5;
+
+// --- WS2812B strip ---
+led_strip_w = 10;        // 10mm wide strip
+
+// --- General ---
+wall = 3;                // Default wall thickness
+m3_clear = 3.2;
+m3_insert = 4.2;         // Heat-set insert hole
+m25_clear = 2.7;
+m5_clear = 5.3;
+tol = 0.2;               // Print tolerance per side

cad/esc_mount.scad

@@ -0,0 +1,70 @@
+// ============================================
+// SaltyLab — ESC Mount
+// 150×100×15mm PETG
+// Hoverboard ESC, mounts to 2020 extrusion
+// ============================================
+include <dimensions.scad>
+
+mount_w = 150;
+mount_d = 100;
+mount_h = 15;
+base_h = 3;
+
+module esc_mount() {
+    difference() {
+        union() {
+            // Base plate
+            translate([-mount_w/2, -mount_d/2, 0])
+                cube([mount_w, mount_d, base_h]);
+            
+            // ESC retaining walls (low lip on 3 sides)
+            // Left
+            translate([-mount_w/2, -mount_d/2, 0])
+                cube([wall, mount_d, mount_h]);
+            // Right
+            translate([mount_w/2 - wall, -mount_d/2, 0])
+                cube([wall, mount_d, mount_h]);
+            // Back
+            translate([-mount_w/2, mount_d/2 - wall, 0])
+                cube([mount_w, wall, mount_h]);
+            
+            // Front clips (snap-fit tabs to hold ESC)
+            for (x = [-30, 30]) {
+                translate([x - 5, -mount_d/2, 0])
+                    cube([10, wall, mount_h]);
+                // Clip overhang
+                translate([x - 5, -mount_d/2, mount_h - 2])
+                    cube([10, wall + 3, 2]);
+            }
+            
+            // 2020 mount tabs (back)
+            for (x = [-25, 25]) {
+                translate([x - 10, mount_d/2 - wall, 0])
+                    cube([20, wall + 8, base_h + 8]);
+            }
+        }
+        
+        // Extrusion bolt holes (M5)
+        for (x = [-25, 25]) {
+            translate([x, mount_d/2 + 3, base_h + 4])
+                rotate([90, 0, 0])
+                    cylinder(d=m5_clear, h=wall + 12, $fn=30);
+        }
+        
+        // Ventilation holes in base
+        for (x = [-40, -20, 0, 20, 40]) {
+            for (y = [-25, 0, 25]) {
+                translate([x, y, -1])
+                    cylinder(d=8, h=base_h + 2, $fn=20);
+            }
+        }
+        
+        // Wire routing slots (front and back)
+        translate([-15, -mount_d/2 - 1, base_h])
+            cube([30, wall + 2, 10]);
+        translate([-15, mount_d/2 - wall - 1, base_h])
+            cube([30, wall + 2, 10]);
+    }
+}
+
+esc_mount();

cad/esp32c3_mount.scad

@@ -0,0 +1,57 @@
+// ============================================
+// SaltyLab — ESP32-C3 Mount
+// 30×25×10mm PETG
+// Tiny mount for LED controller MCU
+// ============================================
+include <dimensions.scad>
+
+mount_w = 30;
+mount_d = 25;
+mount_h = 10;
+base_h = 2;
+
+module esp32c3_mount() {
+    difference() {
+        union() {
+            // Base
+            translate([-mount_w/2, -mount_d/2, 0])
+                cube([mount_w, mount_d, base_h]);
+            
+            // Retaining walls (3 sides, front open for USB)
+            translate([-mount_w/2, -mount_d/2, 0])
+                cube([wall, mount_d, mount_h]);
+            translate([mount_w/2 - wall, -mount_d/2, 0])
+                cube([wall, mount_d, mount_h]);
+            translate([-mount_w/2, mount_d/2 - wall, 0])
+                cube([mount_w, wall, mount_h]);
+            
+            // Clip tabs (front corners)
+            for (x = [-mount_w/2, mount_w/2 - wall]) {
+                translate([x, -mount_d/2, mount_h - 2])
+                    cube([wall, 4, 2]);
+            }
+            
+            // Zip-tie slot wings
+            for (x = [-mount_w/2 - 4, mount_w/2 + 1]) {
+                translate([x, -5, 0])
+                    cube([3, 10, base_h]);
+            }
+        }
+        
+        // Board pocket (recessed)
+        translate([-esp_w/2 - tol, -esp_d/2 - tol, base_h])
+            cube([esp_w + tol*2, esp_d + tol*2, mount_h]);
+        
+        // Zip-tie slots
+        for (x = [-mount_w/2 - 4, mount_w/2 + 1]) {
+            translate([x, -2, -1])
+                cube([3, 4, base_h + 2]);
+        }
+        
+        // USB port clearance (front)
+        translate([-5, -mount_d/2 - 1, base_h])
+            cube([10, wall + 2, 5]);
+    }
+}
+
+esp32c3_mount();

cad/fc_mount.scad

@@ -0,0 +1,86 @@
+// ============================================
+// SaltyLab — Flight Controller Mount
+// Vibration-isolated, 30.5mm pattern
+// TPU dampers + PETG frame
+// ============================================
+include <dimensions.scad>
+
+// FC mount attaches to 2020 extrusion via T-slot
+// Rubber/TPU grommets isolate FC from frame vibration
+
+mount_w = 45;    // Overall width
+mount_d = 45;    // Overall depth  
+mount_h = 15;    // Total height (base + standoffs)
+base_h = 4;      // Base plate thickness
+
+// TPU grommet dimensions
+grommet_od = 7;
+grommet_id = 3.2;  // M3 clearance
+grommet_h = 5;     // Soft mount height
+
+module fc_mount() {
+    difference() {
+        union() {
+            // Base plate
+            translate([-mount_w/2, -mount_d/2, 0])
+                cube([mount_w, mount_d, base_h]);
+            
+            // Standoff posts (PETG, FC sits on TPU grommets on top)
+            for (x = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+                for (y = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+                    translate([x, y, 0])
+                        cylinder(d=8, h=base_h + grommet_h, $fn=30);
+                }
+            }
+            
+            // 2020 extrusion clamp tabs (sides)
+            for (side = [-1, 1]) {
+                translate([side * (extrusion_w/2 + wall), -15, 0])
+                    cube([wall, 30, base_h + 10]);
+            }
+        }
+        
+        // FC mounting holes (M3 through standoffs)
+        for (x = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+            for (y = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+                translate([x, y, -1])
+                    cylinder(d=fc_hole_dia, h=base_h + grommet_h + 2, $fn=25);
+            }
+        }
+        
+        // Extrusion channel (20mm wide slot through base)
+        translate([-extrusion_w/2 - tol, -20, -1])
+            cube([extrusion_w + tol*2, 40, base_h + 2]);
+        
+        // Clamp bolt holes (M3, horizontal through side tabs)
+        for (side = [-1, 1]) {
+            translate([side * (extrusion_w/2 + wall + 1), 0, base_h + 5])
+                rotate([0, 90, 0])
+                    cylinder(d=m3_clear, h=wall + 2, center=true, $fn=25);
+        }
+        
+        // Center cutout for airflow / weight reduction
+        translate([0, 0, -1])
+            cylinder(d=15, h=base_h + 2, $fn=30);
+    }
+}
+
+// TPU grommet (print separately in TPU)
+module tpu_grommet() {
+    difference() {
+        cylinder(d=grommet_od, h=grommet_h, $fn=30);
+        translate([0, 0, -1])
+            cylinder(d=grommet_id, h=grommet_h + 2, $fn=25);
+    }
+}
+
+// Show assembled
+fc_mount();
+
+// Show grommets in position (for visualization)
+%for (x = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+    for (y = [-fc_hole_spacing/2, fc_hole_spacing/2]) {
+        translate([x, y, base_h])
+            tpu_grommet();
+    }
+}

cad/handle.scad

@@ -0,0 +1,59 @@
+// ============================================
+// SaltyLab — Carry Handle
+// 150×30×30mm PETG
+// Comfortable grip, mounts on top of spine
+// ============================================
+include <dimensions.scad>
+
+handle_w = 150;
+handle_h = 30;
+grip_dia = 25;     // Comfortable grip diameter
+grip_len = 100;    // Grip section length
+
+module handle() {
+    difference() {
+        union() {
+            // Grip bar (rounded for comfort)
+            translate([-grip_len/2, 0, handle_h])
+                rotate([0, 90, 0])
+                    cylinder(d=grip_dia, h=grip_len, $fn=40);
+            
+            // Left support leg
+            hull() {
+                translate([-handle_w/2, -10, 0])
+                    cube([20, 20, 3]);
+                translate([-grip_len/2, 0, handle_h])
+                    rotate([0, 90, 0])
+                        cylinder(d=grip_dia, h=5, $fn=40);
+            }
+            
+            // Right support leg
+            hull() {
+                translate([handle_w/2 - 20, -10, 0])
+                    cube([20, 20, 3]);
+                translate([grip_len/2 - 5, 0, handle_h])
+                    rotate([0, 90, 0])
+                        cylinder(d=grip_dia, h=5, $fn=40);
+            }
+        }
+        
+        // 2020 extrusion slot (center of base)
+        translate([-extrusion_w/2 - tol, -extrusion_w/2 - tol, -1])
+            cube([extrusion_w + tol*2, extrusion_w + tol*2, 5]);
+        
+        // M5 bolt holes for extrusion (2x)
+        for (x = [-30, 30]) {
+            translate([x, 0, -1])
+                cylinder(d=m5_clear, h=5, $fn=25);
+        }
+        
+        // Finger grooves on grip
+        for (x = [-30, -10, 10, 30]) {
+            translate([x, 0, handle_h])
+                rotate([0, 90, 0])
+                    cylinder(d=grip_dia + 4, h=5, center=true, $fn=40);
+        }
+    }
+}
+
+handle();

cad/jetson_shelf.scad

@@ -0,0 +1,69 @@
+// ============================================
+// SaltyLab — Jetson Orin Nano Super Shelf
+// 120×100×15mm PETG
+// Mounts Jetson Orin Nano Super to 2020 extrusion
+// ============================================
+include <dimensions.scad>
+
+shelf_w = 120;
+shelf_d = 100;
+shelf_h = 15;
+base_h = 3;
+standoff_h = 8;  // Clearance for Jetson underside components
+
+module jetson_shelf() {
+    difference() {
+        union() {
+            // Base plate
+            translate([-shelf_w/2, -shelf_d/2, 0])
+                cube([shelf_w, shelf_d, base_h]);
+            
+            // Jetson standoffs (M2.5, 86mm × 58mm pattern)
+            for (x = [-jetson_hole_x/2, jetson_hole_x/2]) {
+                for (y = [-jetson_hole_y/2, jetson_hole_y/2]) {
+                    translate([x, y, 0])
+                        cylinder(d=6, h=base_h + standoff_h, $fn=25);
+                }
+            }
+            
+            // 2020 extrusion clamp (back edge)
+            translate([-15, shelf_d/2 - wall, 0])
+                cube([30, wall + 10, base_h + 12]);
+            
+            // Side rails for Jetson alignment
+            for (x = [-jetson_w/2 - wall, jetson_w/2]) {
+                translate([x, -jetson_d/2, base_h + standoff_h])
+                    cube([wall, jetson_d, 4]);
+            }
+        }
+        
+        // Jetson M2.5 holes (through standoffs)
+        for (x = [-jetson_hole_x/2, jetson_hole_x/2]) {
+            for (y = [-jetson_hole_y/2, jetson_hole_y/2]) {
+                translate([x, y, -1])
+                    cylinder(d=jetson_hole_dia, h=base_h + standoff_h + 2, $fn=25);
+            }
+        }
+        
+        // Extrusion bolt hole (M5, through back clamp)
+        translate([0, shelf_d/2 + 3, base_h + 6])
+            rotate([90, 0, 0])
+                cylinder(d=m5_clear, h=wall + 15, $fn=30);
+        
+        // Extrusion channel slot
+        translate([-extrusion_w/2 - tol, shelf_d/2 - wall - 1, -1])
+            cube([extrusion_w + tol*2, wall + 2, base_h + 2]);
+        
+        // Ventilation / cable routing
+        for (x = [-25, 0, 25]) {
+            translate([x, 0, -1])
+                cylinder(d=15, h=base_h + 2, $fn=25);
+        }
+        
+        // USB/Ethernet/GPIO access cutouts (front edge)
+        translate([-jetson_w/2, -shelf_d/2 - 1, base_h])
+            cube([jetson_w, wall + 2, shelf_h]);
+    }
+}
+
+jetson_shelf();

cad/kill_switch_mount.scad

@@ -0,0 +1,56 @@
+// ============================================
+// SaltyLab — Kill Switch Mount
+// 60×60×40mm PETG
+// 22mm panel-mount emergency stop button
+// Mounts to 2020 extrusion, easily reachable
+// ============================================
+include <dimensions.scad>
+
+mount_w = 60;
+mount_d = 60;
+mount_h = 40;
+panel_h = 3;  // Panel face thickness
+
+module kill_switch_mount() {
+    difference() {
+        union() {
+            // Main body (angled face for visibility)
+            hull() {
+                translate([-mount_w/2, 0, 0])
+                    cube([mount_w, mount_d, 1]);
+                translate([-mount_w/2, 5, mount_h])
+                    cube([mount_w, mount_d - 5, 1]);
+            }
+            
+            // 2020 extrusion mount bracket (back)
+            translate([-15, mount_d, 0])
+                cube([30, 10, 20]);
+        }
+        
+        // Kill switch hole (22mm, through angled face)
+        translate([0, mount_d/2, mount_h/2])
+            rotate([10, 0, 0])  // Slight angle for ergonomics
+                cylinder(d=kill_sw_dia + tol, h=panel_h + 2, center=true, $fn=50);
+        
+        // Interior cavity (hollow for switch body)
+        translate([-kill_sw_dia/2 - 3, 5, 3])
+            cube([kill_sw_dia + 6, mount_d - 10, mount_h - 3]);
+        
+        // Wire exit hole (bottom)
+        translate([0, mount_d/2, -1])
+            cylinder(d=10, h=5, $fn=25);
+        
+        // Extrusion bolt holes (M5, through back bracket)
+        for (z = [7, 15]) {
+            translate([-20, mount_d + 5, z])
+                rotate([90, 0, 0])
+                    cylinder(d=m5_clear, h=15, center=true, $fn=25);
+        }
+        
+        // Label recess ("EMERGENCY STOP" — flat area for sticker)
+        translate([-25, 5, mount_h - 1])
+            cube([50, 15, 1.5]);
+    }
+}
+
+kill_switch_mount();

cad/led_diffuser_ring.scad

@@ -0,0 +1,53 @@
+// ============================================
+// SaltyLab — LED Diffuser Ring
+// Ø120×15mm Clear PETG 30% infill
+// Wraps around frame, holds WS2812B strip
+// Print in clear/natural PETG for diffusion
+// ============================================
+include <dimensions.scad>
+
+ring_od = 120;
+ring_id = 110;       // Inner diameter (strip sits inside)
+ring_h = 15;
+strip_channel_w = led_strip_w + 1;  // Strip channel
+strip_channel_d = 3;  // Depth for strip
+
+module led_diffuser_ring() {
+    difference() {
+        // Outer ring
+        cylinder(d=ring_od, h=ring_h, $fn=80);
+        
+        // Inner hollow
+        translate([0, 0, -1])
+            cylinder(d=ring_id, h=ring_h + 2, $fn=80);
+        
+        // LED strip channel (groove on inner wall)
+        translate([0, 0, (ring_h - strip_channel_w)/2])
+            difference() {
+                cylinder(d=ring_id + 2, h=strip_channel_w, $fn=80);
+                cylinder(d=ring_id - strip_channel_d*2, h=strip_channel_w, $fn=80);
+            }
+        
+        // Wire entry slot
+        translate([ring_od/2 - 5, -3, ring_h/2 - 3])
+            cube([10, 6, 6]);
+        
+        // 2020 extrusion clearance (center)
+        translate([-extrusion_w/2 - 5, -extrusion_w/2 - 5, -1])
+            cube([extrusion_w + 10, extrusion_w + 10, ring_h + 2]);
+    }
+    
+    // Mounting tabs (clip onto extrusion, 4x)
+    for (angle = [0, 90, 180, 270]) {
+        rotate([0, 0, angle])
+            translate([extrusion_w/2 + 1, -5, 0])
+                difference() {
+                    cube([3, 10, ring_h]);
+                    translate([-1, 2, ring_h/2])
+                        rotate([0, 90, 0])
+                            cylinder(d=m3_clear, h=5, $fn=20);
+                }
+    }
+}
+
+led_diffuser_ring();

cad/lidar_standoff.scad

@@ -0,0 +1,61 @@
+// ============================================
+// SaltyLab — LIDAR Standoff
+// Ø80×80mm ASA
+// Raises RPLIDAR above all other components
+// for unobstructed 360° scan
+// Connects sensor_tower_top to 2020 extrusion
+// ============================================
+include <dimensions.scad>
+
+standoff_od = 80;
+standoff_h = 80;
+wall_t = 3;
+
+module lidar_standoff() {
+    difference() {
+        union() {
+            // Main cylinder
+            cylinder(d=standoff_od, h=standoff_h, $fn=60);
+            
+            // Bottom flange (bolts to extrusion bracket below)
+            cylinder(d=standoff_od + 10, h=4, $fn=60);
+        }
+        
+        // Hollow interior
+        translate([0, 0, wall_t])
+            cylinder(d=standoff_od - wall_t*2, h=standoff_h, $fn=60);
+        
+        // Cable routing hole (bottom)
+        translate([0, 0, -1])
+            cylinder(d=20, h=wall_t + 2, $fn=30);
+        
+        // Ventilation / weight reduction slots (4x around circumference)
+        for (angle = [0, 90, 180, 270]) {
+            rotate([0, 0, angle])
+                translate([0, standoff_od/2, standoff_h/2])
+                    rotate([90, 0, 0])
+                        hull() {
+                            translate([0, -15, 0])
+                                cylinder(d=10, h=wall_t + 2, center=true, $fn=25);
+                            translate([0, 15, 0])
+                                cylinder(d=10, h=wall_t + 2, center=true, $fn=25);
+                        }
+        }
+        
+        // Bottom flange bolt holes (M5, 4x for mounting)
+        for (angle = [45, 135, 225, 315]) {
+            rotate([0, 0, angle])
+                translate([standoff_od/2, 0, -1])
+                    cylinder(d=m5_clear, h=6, $fn=25);
+        }
+        
+        // Top mating holes (M3, align with sensor_tower_top)
+        for (angle = [0, 90, 180, 270]) {
+            rotate([0, 0, angle])
+                translate([standoff_od/2 - wall_t - 3, 0, standoff_h - 8])
+                    cylinder(d=m3_clear, h=10, $fn=25);
+        }
+    }
+}
+
+lidar_standoff();

cad/motor_mount_plate.scad

@@ -0,0 +1,94 @@
+// ============================================
+// SaltyLab — Motor Mount Plate
+// 350×150×6mm PETG
+// Mounts both 8" hub motors + 2020 extrusion spine
+// ============================================
+include <dimensions.scad>
+
+plate_w = 350;   // Width (axle to axle direction)
+plate_d = 150;   // Depth (front to back)
+plate_h = 6;     // Thickness
+
+// Motor axle positions (centered, symmetric)
+motor_spacing = 280;  // Center-to-center axle distance
+
+// Extrusion spine mount (centered, 2x M5 bolts)
+spine_offset_y = 0;   // Centered front-to-back
+spine_bolt_spacing = 60; // Two bolts along spine
+
+// Motor clamp dimensions
+clamp_w = 30;
+clamp_h = 25;    // Height above plate for clamping axle
+clamp_gap = motor_axle_dia + tol*2;  // Slot for axle
+clamp_bolt_offset = 10; // M5 clamp bolt offset from center
+
+module motor_clamp() {
+    difference() {
+        // Clamp block
+        translate([-clamp_w/2, -clamp_w/2, 0])
+            cube([clamp_w, clamp_w, plate_h + clamp_h]);
+        
+        // Axle hole (through, slightly oversized)
+        translate([0, 0, plate_h + clamp_h/2 + 5])
+            rotate([0, 90, 0])
+                cylinder(d=clamp_gap, h=clamp_w+2, center=true, $fn=40);
+        
+        // Clamp slit (allows tightening)
+        translate([0, 0, plate_h + clamp_h/2 + 5])
+            cube([clamp_w+2, 1.5, clamp_h], center=true);
+        
+        // Clamp bolt holes (M5, horizontal through clamp ears)
+        translate([0, clamp_bolt_offset, plate_h + clamp_h/2 + 5])
+            rotate([0, 90, 0])
+                cylinder(d=m5_clear, h=clamp_w+2, center=true, $fn=30);
+        translate([0, -clamp_bolt_offset, plate_h + clamp_h/2 + 5])
+            rotate([0, 90, 0])
+                cylinder(d=m5_clear, h=clamp_w+2, center=true, $fn=30);
+    }
+}
+
+module motor_mount_plate() {
+    difference() {
+        union() {
+            // Main plate
+            translate([-plate_w/2, -plate_d/2, 0])
+                cube([plate_w, plate_d, plate_h]);
+            
+            // Left motor clamp
+            translate([-motor_spacing/2, 0, 0])
+                motor_clamp();
+            
+            // Right motor clamp
+            translate([motor_spacing/2, 0, 0])
+                motor_clamp();
+            
+            // Reinforcement ribs (bottom)
+            for (x = [-100, 0, 100]) {
+                translate([x - 2, -plate_d/2, 0])
+                    cube([4, plate_d, plate_h]);
+            }
+        }
+        
+        // Extrusion spine bolt holes (M5, 2x along center)
+        for (y = [-spine_bolt_spacing/2, spine_bolt_spacing/2]) {
+            translate([0, y, -1])
+                cylinder(d=m5_clear, h=plate_h+2, $fn=30);
+            // Counterbore for bolt head
+            translate([0, y, plate_h - 2.5])
+                cylinder(d=10, h=3, $fn=30);
+        }
+        
+        // Weight reduction holes
+        for (x = [-70, 70]) {
+            for (y = [-40, 40]) {
+                translate([x, y, -1])
+                    cylinder(d=25, h=plate_h+2, $fn=40);
+            }
+        }
+        
+        // Corner rounding (chamfer edges)
+        // (simplified — round in slicer or add minkowski)
+    }
+}
+
+motor_mount_plate();

cad/realsense_bracket.scad

@@ -0,0 +1,64 @@
+// ============================================
+// SaltyLab — RealSense D435i Bracket
+// 100×50×40mm PETG
+// Adjustable tilt mount on 2020 extrusion
+// ============================================
+include <dimensions.scad>
+
+bracket_w = 100;
+bracket_d = 50;
+bracket_h = 40;
+
+// Camera cradle
+cradle_w = rs_w + wall*2 + tol*2;
+cradle_d = rs_d + wall + tol*2;
+cradle_h = rs_h + 5;
+
+module realsense_bracket() {
+    // Extrusion clamp base
+    difference() {
+        union() {
+            // Clamp block
+            translate([-20, -20, 0])
+                cube([40, 40, 15]);
+            
+            // Tilt arm (vertical, supports camera above)
+            translate([-wall, -wall, 0])
+                cube([wall*2, wall*2, bracket_h]);
+            
+            // Camera cradle at top
+            translate([-cradle_w/2, -cradle_d/2, bracket_h - 5]) {
+                difference() {
+                    cube([cradle_w, cradle_d, cradle_h]);
+                    
+                    // Camera pocket
+                    translate([wall, -1, 3])
+                        cube([rs_w + tol*2, rs_d + tol*2 + 1, rs_h + tol*2]);
+                }
+            }
+            
+            // Tripod mount boss (1/4-20 bolt from bottom of cradle)
+            translate([0, 0, bracket_h - 5])
+                cylinder(d=15, h=3, $fn=30);
+        }
+        
+        // 2020 extrusion channel
+        translate([-extrusion_w/2 - tol, -extrusion_w/2 - tol, -1])
+            cube([extrusion_w + tol*2, extrusion_w + tol*2, 17]);
+        
+        // Clamp bolt (M5, through side)
+        translate([-25, 0, 7.5])
+            rotate([0, 90, 0])
+                cylinder(d=m5_clear, h=50, $fn=30);
+        
+        // Camera 1/4-20 bolt hole (from bottom of cradle)
+        translate([0, 0, bracket_h - 6])
+            cylinder(d=rs_mount_dia, h=10, $fn=30);
+        
+        // Cable routing slot (back of cradle)
+        translate([-10, cradle_d/2 - wall - 1, bracket_h])
+            cube([20, wall + 2, cradle_h - 2]);
+    }
+}
+
+realsense_bracket();

cad/sensor_tower_top.scad

@@ -0,0 +1,58 @@
+// ============================================
+// SaltyLab — Sensor Tower Top
+// 120×120×10mm ASA
+// Mounts RPLIDAR A1 on top of 2020 spine
+// ============================================
+include <dimensions.scad>
+
+top_w = 120;
+top_d = 120;
+top_h = 10;
+base_h = 4;
+
+module sensor_tower_top() {
+    difference() {
+        union() {
+            // Circular plate (RPLIDAR needs 360° clearance)
+            cylinder(d=top_w, h=base_h, $fn=60);
+            
+            // RPLIDAR standoffs (4x M2.5 on 67mm bolt circle)
+            for (i = [0:3]) {
+                angle = i * 90 + 45;  // 45° offset
+                translate([cos(angle) * lidar_mount_circle/2,
+                           sin(angle) * lidar_mount_circle/2, 0])
+                    cylinder(d=6, h=top_h, $fn=25);
+            }
+            
+            // 2020 extrusion socket (bottom center)
+            translate([-extrusion_w/2 - wall, -extrusion_w/2 - wall, -15])
+                cube([extrusion_w + wall*2, extrusion_w + wall*2, 15]);
+        }
+        
+        // RPLIDAR M2.5 through-holes
+        for (i = [0:3]) {
+            angle = i * 90 + 45;
+            translate([cos(angle) * lidar_mount_circle/2,
+                       sin(angle) * lidar_mount_circle/2, -1])
+                cylinder(d=lidar_hole_dia, h=top_h + 2, $fn=25);
+        }
+        
+        // Center hole (RPLIDAR motor shaft clearance + cable routing)
+        translate([0, 0, -1])
+            cylinder(d=25, h=base_h + 2, $fn=40);
+        
+        // 2020 extrusion socket (square hole)
+        translate([-extrusion_w/2 - tol, -extrusion_w/2 - tol, -16])
+            cube([extrusion_w + tol*2, extrusion_w + tol*2, 16]);
+        
+        // Set screw holes for extrusion (M3, 2x perpendicular)
+        for (angle = [0, 90]) {
+            rotate([0, 0, angle])
+                translate([0, extrusion_w/2 + wall, -7.5])
+                    rotate([90, 0, 0])
+                        cylinder(d=m3_clear, h=wall + 5, $fn=25);
+        }
+    }
+}
+
+sensor_tower_top();

cad/tether_anchor.scad

@@ -0,0 +1,46 @@
+// ============================================
+// SaltyLab — Tether Anchor Point
+// 50×50×20mm PETG 100% infill
+// For ceiling tether during balance testing
+// Must be STRONG — 100% infill mandatory
+// ============================================
+include <dimensions.scad>
+
+anchor_w = 50;
+anchor_d = 50;
+anchor_h = 20;
+ring_dia = 30;     // Carabiner ring outer
+ring_hole = 15;    // Carabiner hook clearance
+ring_h = 8;
+
+module tether_anchor() {
+    difference() {
+        union() {
+            // Base (clamps to 2020 extrusion)
+            translate([-anchor_w/2, -anchor_d/2, 0])
+                cube([anchor_w, anchor_d, anchor_h - ring_h]);
+            
+            // Tether ring (stands up from base)
+            translate([0, 0, anchor_h - ring_h])
+                cylinder(d=ring_dia, h=ring_h, $fn=50);
+        }
+        
+        // Ring hole (for carabiner)
+        translate([0, 0, anchor_h - ring_h - 1])
+            cylinder(d=ring_hole, h=ring_h + 2, $fn=40);
+        
+        // 2020 extrusion channel (through base)
+        translate([-extrusion_w/2 - tol, -extrusion_w/2 - tol, -1])
+            cube([extrusion_w + tol*2, extrusion_w + tol*2, anchor_h - ring_h + 2]);
+        
+        // Clamp bolt holes (M5, through sides)
+        for (angle = [0, 90]) {
+            rotate([0, 0, angle])
+                translate([0, anchor_d/2 + 1, (anchor_h - ring_h)/2])
+                    rotate([90, 0, 0])
+                        cylinder(d=m5_clear, h=anchor_d + 2, $fn=25);
+        }
+    }
+}
+
+tether_anchor();

chassis/ASSEMBLY.md

@@ -56,15 +56,24 @@
 3. Fasten 4× M4×12 SHCS. Torque 2.5 N·m.
 4. Insert battery pack; route Velcro straps through slots and cinch.
 
-### 7  FC mount (MAMBA F722S)
+<<<<<<< HEAD
-1. Place silicone anti-vibration grommets onto nylon M3 standoffs.
+### 7  MCU mount (ESP32 BALANCE + ESP32 IO)
-2. Lower FC onto standoffs; secure with M3×6 BHCS. Snug only — do not over-torque.
-3. Orient USB-C port toward front of robot for cable access.
 
-### 8  Jetson Nano mount plate
+> ⚠️ **ARCHITECTURE CHANGE (2026-04-03):** ESP32 BALANCE retired. Two ESP32 boards replace it.
+> Board dimensions and hole patterns TBD — await spec from max before machining mount plate.
+
+=======
+### 7  FC mount (ESP32-S3 BALANCE)
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
+1. Place silicone anti-vibration grommets onto nylon M3 standoffs.
+2. Lower ESP32 BALANCE board onto standoffs; secure with M3×6 BHCS. Snug only.
+3. Mount ESP32 IO board adjacent — exact placement TBD pending board dimensions.
+4. Orient USB connectors toward front of robot for cable access.
+
+### 8  Jetson Orin Nano Super mount plate
 1. Press or thread M3 nylon standoffs (8mm) into plate holes.
 2. Bolt plate to deck: 4× M3×10 SHCS at deck corners.
-3. Set Jetson Nano B01 carrier onto plate standoffs; fasten M3×6 BHCS.
+3. Set Jetson Orin Nano Super B01 carrier onto plate standoffs; fasten M3×6 BHCS.
 
 ### 9  Bumper brackets
 1. Slide 22mm EMT conduit through saddle clamp openings.
@@ -86,7 +95,8 @@
 | Wheelbase (axle C/L to C/L) | 600 mm | ±1 mm |
 | Motor fork slot width | 24 mm | +0.5 / 0 |
 | Motor fork dropout depth | 60 mm | ±0.5 mm |
-| FC hole pattern | 30.5 × 30.5 mm | ±0.2 mm |
+| ESP32 BALANCE hole pattern | TBD — await spec from max | ±0.2 mm |
+| ESP32 IO hole pattern | TBD — await spec from max | ±0.2 mm |
 | Jetson hole pattern | 58 × 58 mm | ±0.2 mm |
 | Battery tray inner | 185 × 72 × 52 mm | +2 / 0 mm |
 

chassis/BOM.md

@@ -41,7 +41,11 @@ PR #7 (`chassis_frame.scad`) used placeholder values. The table below records th
 | 3 | Dropout clamp — upper | 2 | 8mm 6061-T6 Al | 90×70mm blank | D-cut bore; `RENDER="clamp_upper_2d"` |
 | 4 | Stem flange ring | 2 | 6mm Al or acrylic | Ø82mm disc | One above + one below plate; `RENDER="stem_flange_2d"` |
 | 5 | Vertical stem tube | 1 | 38.1mm OD × 1.5mm wall 6061-T6 Al | 1050mm length | 1.5" EMT conduit is a drop-in alternative |
-| 6 | FC standoff M3×6mm nylon | 4 | Nylon | — | MAMBA F722S vibration isolation |
+<<<<<<< HEAD
+| 6 | MCU standoff M3×6mm nylon | 4 | Nylon | — | ESP32 BALANCE / IO board isolation (dimensions TBD) |
+=======
+| 6 | FC standoff M3×6mm nylon | 4 | Nylon | — | ESP32-S3 BALANCE vibration isolation |
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 | 7 | Ø4mm × 16mm alignment pin | 8 | Steel dowel | — | Dropout clamp-to-plate alignment |
 
 ### Battery Stem Clamp (`stem_battery_clamp.scad`) — Part B
@@ -70,7 +74,7 @@ PR #7 (`chassis_frame.scad`) used placeholder values. The table below records th
 | 10 | Motor fork bracket (R) | 1 | 8mm 6061 aluminium | Mirror of item 9 |
 | 11 | Battery tray | 1 | 3mm PETG FDM or 3mm aluminium fold | `chassis_frame.scad` — `battery_tray()` module |
 | 12 | FC mount plate / standoffs | 1 set | PETG or nylon FDM | Includes 4× M3 nylon standoffs, 6mm height |
-| 13 | Jetson Nano mount plate | 1 | 4mm 5052 aluminium or 4mm PETG FDM | B01 58×58mm hole pattern |
+| 13 | Jetson Orin Nano Super mount plate | 1 | 4mm 5052 aluminium or 4mm PETG FDM | B01 58×58mm hole pattern |
 | 14 | Front bumper bracket | 1 | 5mm PETG FDM | Saddle clamps for 22mm EMT conduit |
 | 15 | Rear bumper bracket | 1 | 5mm PETG FDM | Mirror of item 14 |
 
@@ -88,12 +92,23 @@ PR #7 (`chassis_frame.scad`) used placeholder values. The table below records th
 
 ## Electronics Mounts
 
+> ⚠️ **ARCHITECTURE CHANGE (2026-04-03):** ESP32 BALANCE (ESP32) is retired.
+> Replaced by **ESP32 BALANCE** + **ESP32 IO**. Board dimensions and hole patterns TBD — await spec from max.
+
 | # | Part | Qty | Spec | Notes |
 |---|------|-----|------|-------|
-| 13 | STM32 MAMBA F722S FC | 1 | 36×36mm PCB, 30.5×30.5mm M3 mount | Oriented USB-C port toward front |
+<<<<<<< HEAD
+| 13 | ESP32 BALANCE board | 1 | TBD — mount pattern TBD | PID balance loop; replaces ESP32 BALANCE |
+| 13b | ESP32 IO board | 1 | TBD — mount pattern TBD | Motor/sensor/comms I/O |
+| 14 | Nylon M3 standoff 6mm | 4 | F/F nylon | ESP32 board isolation |
+| 15 | Anti-vibration grommet M3 | 4 | Ø6mm silicone | Under ESP32 mount pads |
+| 16 | Jetson Orin module | 1 | 69.6×45mm module + carrier | 58×58mm M3 carrier hole pattern |
+=======
+| 13 | ESP32-S3 ESP32-S3 BALANCE FC | 1 | 36×36mm PCB, 30.5×30.5mm M3 mount | Oriented USB-C port toward front |
 | 14 | Nylon M3 standoff 6mm | 4 | F/F nylon | FC vibration isolation |
 | 15 | Anti-vibration grommet M3 | 4 | Ø6mm silicone | Under FC mount pads |
-| 16 | Jetson Nano B01 module | 1 | 69.6×45mm module + carrier | 58×58mm M3 carrier hole pattern |
+| 16 | Jetson Orin Nano Super B01 module | 1 | 69.6×45mm module + carrier | 58×58mm M3 carrier hole pattern |
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 | 17 | Nylon M3 standoff 8mm | 4 | F/F nylon | Jetson board standoffs |
 
 ---
@@ -144,8 +159,8 @@ Slide entire carousel up/down the stem with M6 collar bolts loosened. Tighten at
 | 26 | M6×60 SHCS  | 4  | ISO 4762, SS | Collar clamping bolts |
 | 27 | M6 hex nut  | 4  | ISO 4032, SS | Captured in collar pockets |
 | 28 | M6×12 set screw | 2 | ISO 4026, SS cup-point | Stem height lock (1 per collar half) |
-| 29 | M3×10 SHCS | 12 | ISO 4762, SS | FC mount + miscellaneous |
+| 29 | M3×10 SHCS | 12 | ISO 4762, SS | ESP32 mount + miscellaneous |
-| 30 | M3×6 BHCS  | 4  | ISO 4762, SS | FC board bolts |
+| 30 | M3×6 BHCS  | 4  | ISO 4762, SS | ESP32 board bolts (qty TBD pending board spec) |
 | 31 | Axle lock nut (match axle tip thread) | 4 | Flanged, confirm thread | 2 per motor |
 | 32 | Flat washer M5 | 32 | SS | |
 | 33 | Flat washer M4 | 32 | SS | |

chassis/ISSUE_505_CHARGING_DOCK_24V_DESIGN.md

@@ -0,0 +1,619 @@
+# Issue #505: 24V Charging Dock Hardware Design
+
+**Agent:** sl-mechanical
+**Status:** In Progress
+**Date Started:** 2026-03-06
+**Related Issues:** #159 (5V dock), #489 (docking node)
+
+---
+
+## Design Overview
+
+Upgraded charging dock system for 24V DC power delivery with improved reliability, higher power capacity, and integrated ArUco marker (ID 42) for precision alignment.
+
+### Key Specifications
+
+| Parameter | Specification | Notes |
+|-----------|---------------|-------|
+| **Voltage** | 24 V DC | Upgrade from 5V (Issue #159) |
+| **Power capacity** | 480 W (20 A @ 24V) | Supports battery charging + auxiliary systems |
+| **Contact type** | Spring-loaded brass pads (Ø12 mm, 2 pads) | 20 mm CL-to-CL spacing |
+| **Alignment method** | V-channel rails + ArUco marker ID 42 | Precision ±15 mm tolerance |
+| **Docking nodes** | Compatible with Issue #489 (ROS2 docking node) | MQTT status reporting |
+| **Frame material** | PETG (3D-printable) | All parts exportable as STL |
+| **Contact height** | 35 mm above dock floor (configurable per robot) | Same as Issue #159 |
+
+---
+
+## Subsystem Design
+
+### A. Power Distribution
+
+#### PSU Selection (24V upgrade)
+
+**Primary:** Mean Well IRM-240-24 or equivalent
+- 240W / 10A @ 24V, open frame
+- Input: 100-240V AC 50/60Hz
+- Output: 24V ±5% regulated
+- Recommended alternatives:
+  - HLK-240M24 (Hi-Link, 240W, compact)
+  - RECOM R-120-24 (half-power option, 120W)
+  - TDK-Lambda DRB-240-24 (industrial grade)
+
+**Specifications:**
+- PCB-mount or chassis-mount (via aluminum bracket)
+- 2× PG7 cable glands for AC input + 24V output
+- Thermal shutdown at 70°C (add heatsink if needed)
+
+#### Power Delivery Cables
+
+| Component | Spec | Notes |
+|-----------|------|-------|
+| PSU to pogo pins | 12 AWG silicone wire (red/black) | 600V rated, max 20A |
+| Cable gland exits | PG7, M20 thread, 5-8 mm cable | IP67 rated |
+| Strain relief | Silicone sleeve, 5 mm ID | 150 mm sections at terminations |
+| Crimp terminals | M3/M4 ring lug, 12 AWG | Solder + crimped (both) |
+
+#### Contact Resistance & Safety
+
+- **Target contact resistance:** <50 mΩ (brass pad to pogo pin)
+- **Transient voltage suppression:** Varistor (MOV) across 24V rail (14-28V clamping)
+- **Inrush current limiting:** NTC thermistor (10Ω @ 25°C) or soft-start relay
+- **Over-current protection:** 25A fuse (slow-blow) on PSU output
+
+---
+
+### B. Mechanical Structure
+
+#### Dock Base Plate
+
+**Material:** PETG (3D-printed)
+**Dimensions:** 300 × 280 × 12 mm (L×W×H)
+**Ballast:** 8× M20 hex nuts (4 pockets, 2 nuts per pocket) = ~690 g stabilization
+
+**Features:**
+- 4× M4 threaded inserts (deck mounting)
+- 4× ballast pockets (underside, 32×32×8 mm each)
+- Wiring channel routing (10×10 mm), PSU mounting rails
+- Cable exit slot with strain relief
+
+#### Back Wall / Pogo Housing
+
+**Material:** PETG
+**Dimensions:** 250 × 85 × 10 mm (W×H×T)
+**Contact face:** 2× pogo pin bores (Ø5.7 mm, 20 mm deep)
+
+**Features:**
+- Pogo pin spring pre-load: 4 mm travel (contact engage at ~3 mm approach)
+- LED status bezel mount (4× 5 mm LED holes)
+- Smooth contact surface (0.4 mm finish to reduce arcing)
+
+#### V-Guide Rails (Left & Right)
+
+**Material:** PETG
+**Function:** Self-aligning funnel for robot receiver plate
+
+**Geometry:**
+- V-channel depth: 15 mm (±7.5 mm from centerline)
+- Channel angle: 60° (Vee angle) for self-centering
+- Guide length: 250 mm (front edge to back wall)
+- 2.5 mm wall thickness (resists impact deformation)
+
+**Design goal:** Robot can approach ±20 mm off-center; V-rails funnel it to ±5 mm at dock contact.
+
+#### ArUco Marker Frame
+
+**Design:** 15 cm × 15 cm frame (150×150 mm outer), marker ID 42
+
+**Frame mounting:**
+- Material: PETG (3D-printed frame + acrylic cover)
+- Marker insertion: Side-slot, captures 100×100 mm laminated ArUco label
+- Position: Dock entrance, 1.5 m height for camera visibility
+- Lighting: Optional white LED ring around frame for contrast
+
+**Marker specs:**
+- Dictionary: `cv2.aruco.getPredefinedDictionary(cv2.aruco.DICT_4X4_250)`
+- Marker ID: 42 (uint8, fits DICT_4X4_250: 0-249)
+- Printed size: 100×100 mm
+- Media: Glossy photo paper + 80 µm lamination (weather protection)
+
+#### PSU Bracket
+
+**Material:** PETG
+**Attachment:** 4× M4 SHCS to base rear, bolts through PSU flanges
+
+**Features:**
+- Mounting pads for PSU feet
+- Cable routing guides (AC input + 24V output)
+- Thermal airflow clearance (30 mm minimum)
+- Optional DIN-rail adapter (for rackmount variant)
+
+#### LED Status Bezel
+
+**Material:** PETG
+**Function:** 4× LED indicator display (charging state feedback)
+
+**LEDs & Resistors:**
+
+| LED | Color | State | Vf (typ) | Resistor | Notes |
+|-----|-------|-------|----------|----------|-------|
+| L1 | Red | SEARCHING | 2.0 V | 180 Ω | No robot contact |
+| L2 | Yellow | ALIGNED | 2.1 V | 180 Ω | Contact made, BMS pre-charge |
+| L3 | Blue | CHARGING | 3.2 V | 100 Ω | Active charging |
+| L4 | Green | FULL | 2.1 V | 180 Ω | Trickle/float mode |
+
+**Current calculation (for 24V rail):**
+- Red/Yellow/Green: R = (24 − Vf) / 0.020 ≈ 1000 Ω (use 1.0 kΩ 1/4W)
+- Blue: R = (24 − 3.2) / 0.020 = 1040 Ω (use 1.0 kΩ)
+
+**Control:**
+- Jetson Orin NX GPIO output (via I2C LED driver or direct GPIO)
+- Pulldown resistor (10 kΩ) on each GPIO if using direct drive
+- Alternative: TP4056 analog output pins (if in feedback path)
+
+---
+
+### C. Robot Receiver (Mating Interface)
+
+**Cross-variant compliance:** Same receiver design works for SaltyLab, SaltyRover, SaltyTank with different mounting interfaces.
+
+#### Contact Pads
+
+- **Material:** Bare brass (10-12 mm OD, 2 mm thick)
+- **Pressing:** 0.1 mm interference fit into PETG housing
+- **Polarity marking:** "+" slot on right side (+X), "-" unmarked on left
+- **Solder lug:** M3 ring lug on rear face (connects to robot BMS)
+
+#### V-Nose Guide
+
+- **Profile:** Chamfered 14° V-nose (30 mm wide)
+- **Function:** Mates with dock V-rails for alignment funnel
+
+#### Mounting Variants
+
+| Robot | Mount Type | Fastener | Height Adjustment |
+|-------|-----------|----------|------------------|
+| SaltyLab | Stem collar (split, 2×) | M4 × 16 SHCS (2×) | Tune via firmware offset |
+| SaltyRover | Deck flange (bolt-on) | M4 × 16 SHCS (4×) | 20 mm shim if needed |
+| SaltyTank | Skid plate (bolt-on) | M4 × 16 SHCS (4×) | 55 mm ramp shim recommended |
+
+---
+
+## 3D-Printable Parts (STL Exports)
+
+All parts print in PETG, 0.2 mm layer height, 40-60% infill:
+
+| Part | File | Qty | Infill | Est. Mass | Notes |
+|------|------|-----|--------|----------|-------|
+| Dock base | `charging_dock_505.scad` (base_stl) | 1 | 60% | ~420 g | Print on large bed (300×280 mm) |
+| Back wall + pogo | `charging_dock_505.scad` (back_wall_stl) | 1 | 40% | ~140 g | Smooth face finish required |
+| V-rail left | `charging_dock_505.scad` (guide_rail_stl) | 1 | 50% | ~65 g | Mirror for right side in slicer |
+| V-rail right | *(mirror of left)* | 1 | 50% | ~65 g | — |
+| ArUco frame | `charging_dock_505.scad` (aruco_frame_stl) | 1 | 30% | ~35 g | Slot accepts 100×100 mm marker |
+| PSU bracket | `charging_dock_505.scad` (psu_bracket_stl) | 1 | 40% | ~45 g | — |
+| LED bezel | `charging_dock_505.scad` (led_bezel_stl) | 1 | 40% | ~15 g | — |
+| **Receiver (Lab)** | `charging_dock_receiver_505.scad` (lab_stl) | 1 | 60% | ~32 g | Stem collar variant |
+| **Receiver (Rover)** | `charging_dock_receiver_505.scad` (rover_stl) | 1 | 60% | ~36 g | Deck flange variant |
+| **Receiver (Tank)** | `charging_dock_receiver_505.scad` (tank_stl) | 1 | 60% | ~42 g | Extended nose variant |
+
+---
+
+## Bill of Materials (BOM)
+
+### Electrical Components
+
+#### Power Supply & Wiring
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| E1 | PSU — 24V 10A | Mean Well IRM-240-24 or Hi-Link HLK-240M24 | 1 | ~$40–60 | ~$50 | Digi-Key, Amazon |
+| E2 | 12 AWG silicone wire | Red + black, 600V rated, 5 m spool | 1 | ~$15 | ~$15 | McMaster-Carr, AliExpress |
+| E3 | PG7 cable gland | M20 thread, IP67, 5–8 mm cable | 2 | ~$3 | ~$6 | AliExpress, Heilind |
+| E4 | Varistor (MOV) | 18–28V, 1 kA | 1 | ~$1 | ~$1 | Digi-Key |
+| E5 | Fuse — 25A | T25 slow-blow, 5×20 mm | 1 | ~$0.50 | ~$0.50 | Digi-Key |
+| E6 | Fuse holder | 5×20 mm inline, 20A rated | 1 | ~$2 | ~$2 | Amazon |
+| E7 | Crimp ring terminals | M3, 12 AWG, tin-plated | 8 | ~$0.20 | ~$1.60 | Heilind, AliExpress |
+| E8 | Strain relief sleeve | 5 mm ID silicone, 1 m | 1 | ~$5 | ~$5 | McMaster-Carr |
+
+#### Pogo Pins & Contacts
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| C1 | Pogo pin assembly | Spring-loaded, Ø5.5 mm OD, 20 mm, 20A rated, 4 mm travel | 2 | ~$8–12 | ~$20 | Preci-Dip, Jst, AliExpress |
+| C2 | Brass contact pad | Ø12 × 2 mm, H68 brass, bare finish | 2 | ~$3 | ~$6 | Metal supplier (Metals USA, OnlineMetals) |
+| C3 | Solder lug — M3 | Copper ring, tin-plated | 4 | ~$0.40 | ~$1.60 | Heilind, Amazon |
+
+#### LED Status Circuit
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| L1 | 5 mm LED — Red | 2.0 V, 20 mA, diffuse | 1 | ~$0.30 | ~$0.30 | Digi-Key |
+| L2 | 5 mm LED — Yellow | 2.1 V, 20 mA, diffuse | 1 | ~$0.30 | ~$0.30 | Digi-Key |
+| L3 | 5 mm LED — Blue | 3.2 V, 20 mA, diffuse | 1 | ~$0.50 | ~$0.50 | Digi-Key |
+| L4 | 5 mm LED — Green | 2.1 V, 20 mA, diffuse | 1 | ~$0.30 | ~$0.30 | Digi-Key |
+| R1–R4 | Resistor — 1 kΩ 1/4W | Metal film, 1% tolerance | 4 | ~$0.10 | ~$0.40 | Digi-Key |
+| J1 | Pin header 2.54 mm | 1×6 right-angle | 1 | ~$0.50 | ~$0.50 | Digi-Key |
+
+#### Current Sensing (Optional)
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| S1 | INA219 I2C shunt monitor | 16-bit, I2C addr 0x40, 26V max | 1 | ~$5 | ~$5 | Adafruit, Digi-Key |
+| S2 | SMD resistor — 0.1 Ω | 1206, 1W | 1 | ~$1 | ~$1 | Digi-Key |
+
+### Mechanical Hardware
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| M1 | M20 hex nut | Steel DIN 934, ~86 g | 8 | ~$0.80 | ~$6.40 | Grainger, Home Depot |
+| M2 | M4 × 16 SHCS | Stainless A4 DIN 912 | 16 | ~$0.30 | ~$4.80 | Grainger |
+| M3 | M4 × 10 BHCS | Stainless A4 DIN 7380 | 8 | ~$0.25 | ~$2.00 | Grainger |
+| M4 | M4 heat-set insert | Brass, threaded, M4 | 20 | ~$0.15 | ~$3.00 | McMaster-Carr |
+| M5 | M3 × 16 SHCS | Stainless, LED bezel | 4 | ~$0.20 | ~$0.80 | Grainger |
+| M6 | M3 hex nut | DIN 934 | 4 | ~$0.10 | ~$0.40 | Grainger |
+| M7 | M8 × 40 BHCS | Zinc-plated, floor anchors (optional) | 4 | ~$0.50 | ~$2.00 | Grainger |
+| M8 | Rubber foot | Ø20 × 5 mm, self-adhesive | 4 | ~$0.80 | ~$3.20 | Amazon |
+
+### ArUco Marker & Frame
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| A1 | ArUco marker print | 100×100 mm, ID=42, DICT_4X4_250, glossy photo paper | 2 | ~$1.50 | ~$3.00 | Print locally or AliExpress |
+| A2 | Lamination pouch | A4, 80 µm thick | 2 | ~$0.40 | ~$0.80 | Amazon, Staples |
+| A3 | Acrylic cover sheet | Clear, 3 mm, 150×150 mm | 1 | ~$3 | ~$3.00 | McMaster-Carr |
+
+### Consumables & Assembly
+
+| # | Description | Spec | Qty | Unit Cost | Total | Source |
+|---|---|---|---|---|---|---|
+| X1 | Solder wire | 63/37 Sn/Pb or lead-free, 1 m | 1 | ~$3 | ~$3.00 | Digi-Key |
+| X2 | Flux paste | No-clean, 25 mL | 1 | ~$4 | ~$4.00 | Digi-Key |
+| X3 | Loctite 243 | Thread-locker (medium strength), 10 mL | 1 | ~$4 | ~$4.00 | Grainger |
+| X4 | Epoxy adhesive | Two-part, 25 mL | 1 | ~$6 | ~$6.00 | Home Depot |
+
+---
+
+## Assembly Procedure
+
+### Phase 1: Preparation
+
+1. **Print all PETG parts** (see STL export list above)
+   - Base: 0.3 mm layer, 60% infill (heavy/stable)
+   - Back wall: 0.2 mm, 40% infill
+   - Rails & brackets: 0.2 mm, 40-50% infill
+   - Support removal: slow, avoid pogo bore damage
+
+2. **Prepare ballast nuts**
+   - Sort 8× M20 hex nuts (stack in 4 pockets, 2 per pocket)
+   - Optional: fill pockets with epoxy to prevent rattling
+
+3. **Press brass contact pads**
+   - Apply 0.1 mm interference press-fit into receiver housing bores
+   - Use arbor press @ ~2 tons force
+   - Or use slow manual press (avoid chipping brass edges)
+
+### Phase 2: Base Assembly
+
+4. **Install heat-set M4 inserts** into base plate
+   - Back wall attach points (3×)
+   - Guide rail attach points (4× each side)
+   - ArUco mast feet (4×)
+   - PSU bracket mount (4×)
+   - Use soldering iron (350°C) or insert tool, press vertically
+
+5. **Ballast installation**
+   - Insert M20 hex nuts into base pockets (from underside)
+   - Verify pockets are flush, no protrusions into wiring channel
+   - Optional: epoxy-lock nuts with 5-minute epoxy
+
+6. **Install pogo pins** into back wall
+   - Press spring-loaded pins from front face into Ø5.7 mm bores (20 mm deep)
+   - Flange seats against counterbore shoulder at 1.5 mm depth
+   - Apply small drop of Loctite 243 to bore wall (prevents rotation)
+
+### Phase 3: Electrical Assembly
+
+7. **Solder wires to pogo pin terminals**
+   - 12 AWG red wire → POGO+ pin
+   - 12 AWG black wire → POGO- pin
+   - Solder both in & out of lug for redundancy
+   - Add ~50 mm strain relief sleeve over each joint
+
+8. **Route pogo wires through base wiring channel**
+   - Guide down channel (10×10 mm trough)
+   - Exit through cable gland slot on rear
+
+9. **Assemble PSU bracket**
+   - Bolt Mean Well IRM-240-24 (or equivalent) to bracket pads
+   - 4× M4 fasteners through bracket to base rear
+   - Orient PSU exhaust away from dock (for ventilation)
+
+10. **Connect 24V wiring**
+    - Pogo+ wire (red) → PSU V+ terminal
+    - Pogo- wire (black) → PSU COM/GND terminal
+    - Observe polarity strictly (reverse = short circuit)
+
+11. **Install power protection**
+    - Fuse holder in-line on PSU V+ output (25A slow-blow)
+    - Varistor (MOV, 18–28V) across V+/COM rails (clamp transients)
+    - Optional: NTC thermistor (10Ω @ 25°C) in series for soft-start
+
+12. **Wire AC mains input** (if not pre-assembled)
+    - Route AC input through cable gland on PSU bracket
+    - Connect to PSU AC terminals (L, N, PE if applicable)
+    - Ensure all connections are soldered + crimped
+
+### Phase 4: LED Assembly
+
+13. **Install LED bezel into back wall**
+    - 4× 5 mm LEDs press-fit into bezel holes (bodies recessed ~2 mm)
+    - Solder resistors (1 kΩ 1/4W) to LED anodes on rear
+    - Connect all LED cathodes to common GND line (black wire to PSU COM)
+    - Wire LED control lines to Jetson Orin NX GPIO (via I2C expander if needed)
+
+14. **Connect LED header**
+    - 2.54 mm pin header (1×6) plugs into LED control harness
+    - Pin 1: LED1 (red, SEARCHING)
+    - Pin 2: LED2 (yellow, ALIGNED)
+    - Pin 3: LED3 (blue, CHARGING)
+    - Pin 4: LED4 (green, FULL)
+    - Pins 5–6: GND, +24V (power for LED feedback monitoring)
+
+### Phase 5: Mechanical Assembly
+
+15. **Bolt back wall to base**
+    - 3× M4×16 SHCS from underside of base
+    - Tighten to ~5 Nm (snug, don't overtighten plastic)
+    - Back wall should be perpendicular to base (verify with level)
+
+16. **Attach V-guide rails**
+    - Left rail: 4× M4 fasteners into base inserts (front & rear attach)
+    - Right rail: Mirror (flip STL in slicer) or manually mirror geometry
+    - Verify V-channels are parallel & symmetrical (±2 mm tolerance)
+
+17. **Mount ArUco marker frame**
+    - Bolt 4× M4×10 fasteners to frame feet (attach to base front)
+    - Insert laminated 100×100 mm ArUco marker (ID 42) into frame slot
+    - Verify marker is flat & centered (no curl or shadow)
+
+18. **Attach rubber feet** (or floor anchors)
+    - 4× self-adhesive rubber feet on base underside corners
+    - OR drill M8 holes through base (optional: permanent floor mounting)
+
+### Phase 6: Robot Receiver Assembly
+
+19. **Assemble robot receiver** (per variant)
+    - **SaltyLab:** 2-piece stem collar (M4×16 clamps Ø25 mm stem)
+    - **SaltyRover:** Single flange piece (4× M4 to deck underbelly)
+    - **SaltyTank:** Single piece w/ extended nose (4× M4 to skid plate)
+
+20. **Press brass pads into receiver**
+    - Ø12 mm pads press into 0.1 mm interference bores
+    - Apply Loctite 603 retaining compound to bore before pressing
+    - Manual arbor press @ ~1-2 tons force; pads should be proud 0.2 mm
+
+21. **Solder receiver wires**
+    - 12 AWG wires (red/black) solder to M3 solder lugs on pad rear
+    - Route wires through wire channel on mount face
+    - Terminate to robot BMS/charging PCB input
+
+---
+
+## Wiring Diagram (24V System)
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│                       MAINS INPUT (AC)                       │
+│                        110/220 V AC                          │
+└────────────┬────────────────────────────────────────────────┘
+             │
+             ▼
+      ┌──────────────┐
+      │  IRM-240-24  │  24V / 10A out (240W)
+      │   PSU        │  ±5% regulated, open-frame
+      └──┬───────┬───┘
+    +24V │       │ GND
+         │       │
+    ┌────┴┐   ┌─┴────┐
+    │ [F] │   │ [F]  │  Fuse holder (25A slow-blow)
+    │     │   │      │
+    │ +24 │   │ GND  │  12 AWG silicone wire to back wall
+    │     │   │      │
+    └────┬┘   └─┬────┘
+         │     │
+    +24V│     │GND
+        ▼     ▼
+    ┌─────────────────┐
+    │  Back wall      │
+    │  ┌───────────┐  │
+    │  │  POGO+    │  │ Spring-loaded contact pin (+24V)
+    │  │  POGO-    │  │ Spring-loaded contact pin (GND)
+    │  └────┬──────┘  │
+    │       │         │
+    │ ┌─────┴─────┐   │
+    │ │  LED 1-4  │   │ Red, Yellow, Blue, Green indicators
+    │ │  Resistors│   │ 1 kΩ limiting resistors (×4)
+    │ │  [GPIO]   │   │ Control from Jetson Orin NX I2C
+    │ └───────────┘   │
+    └─────┬───────────┘
+          │
+     ═════╧════════ DOCK / ROBOT AIR GAP (≤50 mm) ═════════════
+          │
+          ▼
+    ┌──────────────────┐
+    │  Robot Receiver  │
+    │  ┌────────────┐  │
+    │  │ Contact +  │  │ Brass pad (Ø12×2 mm) [+24V]
+    │  │ Contact -  │  │ Brass pad (Ø12×2 mm) [GND]
+    │  └──┬──┬──────┘  │
+    │     │  │         │
+    │   12 AWG wires   │ Red/black to BMS
+    │     │  │         │
+    │  ┌──▼──▼──┐      │
+    │  │ Robot  │      │
+    │  │ BMS    │      │
+    │  │Battery │      │ Charging current: 0–15A (typical)
+    │  └────────┘      │
+    └──────────────────┘
+
+OPTIONAL — CURRENT SENSING (Diagnostic)
+         │ +24V
+    ┌────┴────┐
+    │[INA219] │ I2C current monitor (0.1Ω sense resistor)
+    │ I2C 0x40│ Jetson reads dock current → state machine
+    └────┬────┘
+         │ GND
+
+LED STATE MACHINE CONTROL (from docking_node.py):
+    State          GPIO/Signal    LED Output
+    ─────────────────────────────────────────
+    SEARCHING      GPIO H         Red LED ON (20 mA, 1 kΩ)
+    ALIGNED        GPIO H         Yellow LED ON (pre-charge active)
+    CHARGING       GPIO H         Blue LED ON (>1 A charging)
+    FULL/COMPLETE  GPIO H         Green LED ON (float mode)
+
+    GPIO driven via Jetson Orin NX I2C LED driver (e.g., PCA9685)
+    or direct GPIO if firmware implements bitbang logic.
+```
+
+---
+
+## Integration with ROS2 Docking Node (#489)
+
+**Docking node location:** `./jetson/ros2_ws/src/saltybot_docking/docking_node.py`
+
+### MQTT Topics
+
+**Status reporting (outbound):**
+```
+saltybot/docking/status  → { state, robot_id, contact_voltage, charge_current }
+saltybot/docking/led     → { red, yellow, blue, green }  [0=OFF, 1=ON, blink_hz]
+```
+
+**Command subscriptions (inbound):**
+```
+saltybot/docking/reset   → trigger dock reset (clear fault)
+saltybot/docking/park    → move robot out of dock (e.g., after full charge)
+```
+
+### Firmware Integration
+
+**State machine (4 states):**
+1. **SEARCHING** — No robot contact; dock waits for approach (ArUco marker detection via Jetson camera)
+2. **ALIGNED** — Contact made (BMS pre-charge active); dock supplies trickle current (~100 mA) while robot capacitors charge
+3. **CHARGING** — Main charge active; dock measures current via INA219, feedback to BMS
+4. **FULL** — Target voltage reached (≥23.5 V, <100 mA draw); dock holds float voltage
+
+**Current sensing feedback:**
+- INA219 I2C shunt on 24V rail monitors dock-to-robot current
+- Jetson polls at 10 Hz; state transitions trigger LED updates & MQTT publish
+- Hysteresis prevents flickering (state valid for ≥2 sec)
+
+---
+
+## Testing Checklist
+
+- [ ] **Electrical safety**
+  - [ ] 24V output isolated from mains AC (< 2.5 kV isolation @ 60 Hz)
+  - [ ] Fuse 25A blocks short-circuit (verify blow @ >30 A)
+  - [ ] Varistor clamps transient overvoltage (check 28V limit)
+  - [ ] All crimps are soldered + crimped (pull test: no slippage @ 10 lbf)
+
+- [ ] **Mechanical**
+  - [ ] Base level on 4 rubber feet (no rocking)
+  - [ ] V-rails parallel within ±2 mm across 250 mm length
+  - [ ] Back wall perpendicular to base (level ±1°)
+  - [ ] Pogo pins extend 4 mm from back wall face (spring preload correct)
+
+- [ ] **Contact alignment**
+  - [ ] Robot receiver pads contact pogo pins with ≥3 mm contact face overlap
+  - [ ] Contact resistance < 50 mΩ (measure with multimeter on lowest ohm scale during light press)
+  - [ ] No visible arcing or pitting (inspect pads after 10 charge cycles)
+
+- [ ] **Power delivery**
+  - [ ] 24V output at PSU: 23.5–24.5 V (under load)
+  - [ ] 24V at pogo pins: ≥23.5 V (< 0.5 V droop @ 10 A)
+  - [ ] Robot receives 24V ± 1 V (measure at BMS input)
+
+- [ ] **LED status**
+  - [ ] Red (SEARCHING) steady on before robot approach
+  - [ ] Yellow (ALIGNED) turns on when pads make contact
+  - [ ] Blue (CHARGING) turns on when charge current > 500 mA
+  - [ ] Green (FULL) turns on when current drops < 100 mA (float mode)
+
+- [ ] **ArUco marker**
+  - [ ] Marker ID 42 is readable by Jetson camera from 1.5 m @ 90° angle
+  - [ ] No glare or shadow on marker (add diffuse lighting if needed)
+  - [ ] Marker detected by cv2.aruco in < 100 ms
+
+- [ ] **MQTT integration**
+  - [ ] Dock publishes status every 5 sec (or on state change)
+  - [ ] LED state matches reported dock state
+  - [ ] Current sensing (INA219) reads within ±2% of true dock current
+
+---
+
+## Firmware/Software Requirements
+
+### Jetson Orin NX (Docking controller)
+
+**Python dependencies:**
+```bash
+pip install opencv-contrib-python  # ArUco marker detection
+pip install adafruit-circuitpython-ina219  # Current sensing
+pip install rclpy  # ROS2
+pip install paho-mqtt  # MQTT status reporting
+```
+
+**Key Python modules:**
+- `cv2.aruco.getPredefinedDictionary(cv2.aruco.DICT_4X4_250)` → ArUco ID 42 detection
+- `Adafruit_INA219` → I2C current monitoring @ 0x40
+- GPIO library → LED control (via I2C LED driver or direct GPIO)
+
+**ROS2 node:** `saltybot_docking/docking_node.py` (already present, Issue #489)
+- Subscribes to `/docking/approach_request`
+- Publishes to `/docking/status`, `/docking/led_state`
+- MQTT gateway for legacy systems
+
+---
+
+## Files to Commit
+
+**New files for Issue #505:**
+```
+chassis/
+├── charging_dock_505.scad              [Main dock 24V design]
+├── charging_dock_receiver_505.scad     [Robot receiver 24V variant]
+├── ISSUE_505_CHARGING_DOCK_24V_DESIGN.md  [This file]
+├── charging_dock_505_BOM.csv           [Excel-friendly BOM export]
+└── charging_dock_505_WIRING_DIAGRAM.md [Detailed wiring guide]
+
+docs/
+└── Issue_505_Assembly_Guide.md  [Step-by-step assembly photos + text]
+```
+
+---
+
+## Revision History
+
+| Date | Version | Changes |
+|------|---------|---------|
+| 2026-03-06 | 1.0 | Initial design (24V upgrade from Issue #159) |
+
+---
+
+## Next Steps
+
+1. ✅ Design specification (this document)
+2. ⏳ OpenSCAD CAD files (`charging_dock_505.scad`, `charging_dock_receiver_505.scad`)
+3. ⏳ BOM export (CSV format for procurement)
+4. ⏳ 3D-printed prototype testing
+5. ⏳ Electrical integration with Jetson docking node
+6. ⏳ ArUco marker calibration & documentation
+7. ⏳ PR submission & merge to `main`
+
+---
+
+**Designer:** sl-mechanical
+**Date:** 2026-03-06
+**Status:** Design Specification Complete — Awaiting CAD Implementation

chassis/battery_holder.scad

@@ -0,0 +1,410 @@
+// ============================================================
+// battery_holder.scad — 6S LiPo Battery Holder for 2020 T-Slot Chassis
+// Issue: #588  Agent: sl-mechanical  Date: 2026-03-14
+// ============================================================
+//
+// Parametric bracket holding a 6S 5000 mAh LiPo pack on 2020 aluminium
+// T-slot rails.  Designed for low centre-of-gravity mounting: pack sits
+// flat between the two chassis rails, as close to ground as clearance
+// allows.  Quick-release via captive Velcro straps — battery swap in
+// under 60 s without tools.
+//
+// Architecture:
+//   Tray        → flat floor + perimeter walls, battery sits inside
+//   Rail saddles→ two T-nut feet drop onto 2020 rails, thumbscrew locks
+//   Strap slots → four pairs of slots for 25 mm Velcro strap loops
+//   XT60 window → cut-out in rear wall for XT60 connector exit
+//   Balance port→ open channel in front wall for balance lead routing
+//   QR tab      → front-edge pull tab for one-handed battery extraction
+//
+// Part catalogue:
+//   Part 1 — battery_tray()    Main tray body (single-piece print)
+//   Part 2 — rail_saddle()     T-nut saddle foot (print x2 per tray)
+//   Part 3 — strap_guide()     25 mm Velcro strap guide (print x4)
+//   Part 4 — assembly_preview()
+//
+// Hardware BOM:
+//   2× M3 × 16 mm SHCS + M3 hex nut    T-nut rail clamp thumbscrews
+//   2× 25 mm × 250 mm Velcro strap     battery retention (hook + loop)
+//   1× XT60 female connector            (mounted on ESC/PDB harness)
+//   — battery slides in from front, Velcro strap over top —
+//
+// 6S LiPo target pack (verify with calipers — packs vary by brand):
+//   BATT_L = 155 mm  (length, X axis in tray)
+//   BATT_W =  48 mm  (width,  Y axis in tray)
+//   BATT_H =  52 mm  (height, Z axis in tray)
+//   Clearance 1 mm each side added automatically (BATT_CLEAR)
+//
+// Mounting:
+//   Rail span    : RAIL_SPAN — distance between 2020 rail centrelines
+//                  Default 80 mm; adjust to chassis rail spacing
+//   Saddle height: SADDLE_H — total height of saddle (tray floor above rail)
+//                  Keep low for CoG; default 8 mm
+//
+// RENDER options:
+//   "assembly"         full assembly preview (default)
+//   "tray_stl"         Part 1 — battery tray
+//   "saddle_stl"       Part 2 — rail saddle (print x2)
+//   "strap_guide_stl"  Part 3 — strap guide (print x4)
+//
+// Export commands:
+//   openscad battery_holder.scad -D 'RENDER="tray_stl"'        -o bh_tray.stl
+//   openscad battery_holder.scad -D 'RENDER="saddle_stl"'      -o bh_saddle.stl
+//   openscad battery_holder.scad -D 'RENDER="strap_guide_stl"' -o bh_strap_guide.stl
+//
+// Print settings (all parts):
+//   Material   : PETG
+//   Perimeters : 5 (tray, saddle), 3 (strap_guide)
+//   Infill     : 40 % gyroid (tray floor, saddle), 20 % (strap_guide)
+//   Orientation:
+//     tray         — floor flat on bed (no supports needed)
+//     saddle       — flat face on bed (no supports)
+//     strap_guide  — flat face on bed (no supports)
+// ============================================================
+
+$fn = 64;
+e   = 0.01;
+
+// ── Battery pack dimensions (verify with calipers) ────────────────────────────
+BATT_L     = 155.0;   // pack length (X)
+BATT_W     =  48.0;   // pack width  (Y)
+BATT_H     =  52.0;   // pack height (Z)
+BATT_CLEAR =   1.0;   // per-side fit clearance
+
+// ── Tray geometry ─────────────────────────────────────────────────────────────
+TRAY_FLOOR_T   =  4.0;   // tray floor thickness
+TRAY_WALL_T    =  4.0;   // tray perimeter wall thickness
+TRAY_WALL_H    = 20.0;   // tray wall height (Z) — cradles lower half of pack
+TRAY_FILLET_R  =  3.0;   // inner corner radius
+
+// Inner tray cavity (battery + clearance)
+TRAY_INN_L = BATT_L + 2*BATT_CLEAR;
+TRAY_INN_W = BATT_W + 2*BATT_CLEAR;
+
+// Outer tray footprint
+TRAY_OUT_L = TRAY_INN_L + 2*TRAY_WALL_T;
+TRAY_OUT_W = TRAY_INN_W + 2*TRAY_WALL_T;
+TRAY_TOTAL_H = TRAY_FLOOR_T + TRAY_WALL_H;
+
+// ── Rail interface ─────────────────────────────────────────────────────────────
+RAIL_SPAN   =  80.0;   // distance between 2020 rail centrelines (Y)
+RAIL_W      =  20.0;   // 2020 extrusion width
+SLOT_NECK_H =   3.2;   // T-slot neck height
+SLOT_OPEN   =   6.0;   // T-slot opening width
+SLOT_INN_W  =  10.2;   // T-slot inner width
+SLOT_INN_H  =   5.8;   // T-slot inner height
+
+// ── T-nut / saddle geometry ───────────────────────────────────────────────────
+TNUT_W       =  9.8;
+TNUT_H       =  5.5;
+TNUT_L       = 12.0;
+TNUT_NUT_AF  =  5.5;   // M3 hex nut across-flats
+TNUT_NUT_H   =  2.4;
+TNUT_BOLT_D  =  3.3;   // M3 clearance
+
+SADDLE_W     = 30.0;   // saddle foot width (X, along rail)
+SADDLE_T     =  8.0;   // saddle body thickness (Z, above rail top face)
+SADDLE_PAD_T =  2.0;   // rubber-pad recess depth (optional anti-slip)
+
+// ── Velcro strap slots ────────────────────────────────────────────────────────
+STRAP_W      = 26.0;   // 25 mm strap + 1 mm clearance
+STRAP_T      =  4.0;   // slot through-thickness (tray wall)
+// Four slot pairs: one near each end of tray (X), one each side (Y)
+// Slots run through side walls (Y direction) — strap loops over battery top
+
+// ── XT60 connector window (rear wall) ─────────────────────────────────────────
+XT60_W       = 14.0;   // XT60 body width
+XT60_H       = 18.0;   // XT60 body height (with cable exit)
+XT60_OFFSET_Z = 4.0;   // height above tray floor
+
+// ── Balance lead port (front wall) ────────────────────────────────────────────
+BAL_W        = 40.0;   // balance lead bundle width (6S = 7 wires)
+BAL_H        =  6.0;   // balance lead channel height
+BAL_OFFSET_Z =  8.0;   // height above tray floor
+
+// ── Quick-release pull tab (front edge) ──────────────────────────────────────
+QR_TAB_W     = 30.0;   // tab width
+QR_TAB_H     = 12.0;   // tab height above front wall top
+QR_TAB_T     =  4.0;   // tab thickness
+QR_HOLE_D    = 10.0;   // finger-loop hole diameter
+
+// ── Strap guide clip ─────────────────────────────────────────────────────────
+GUIDE_OD     = STRAP_W + 6.0;
+GUIDE_T      =  3.0;
+GUIDE_BODY_H = 14.0;
+
+// ── Fasteners ─────────────────────────────────────────────────────────────────
+M3_D = 3.3;
+
+// ============================================================
+// RENDER DISPATCH
+// ============================================================
+RENDER = "assembly";
+
+if      (RENDER == "assembly")        assembly_preview();
+else if (RENDER == "tray_stl")        battery_tray();
+else if (RENDER == "saddle_stl")      rail_saddle();
+else if (RENDER == "strap_guide_stl") strap_guide();
+
+// ============================================================
+// ASSEMBLY PREVIEW
+// ============================================================
+module assembly_preview() {
+    // Ghost 2020 rails (Y direction, RAIL_SPAN apart)
+    for (ry = [-RAIL_SPAN/2, RAIL_SPAN/2])
+        %color("Silver", 0.28)
+            translate([-TRAY_OUT_L/2 - 30, ry - RAIL_W/2, -SADDLE_T - TNUT_H])
+                cube([TRAY_OUT_L + 60, RAIL_W, RAIL_W]);
+
+    // Rail saddles (left and right)
+    for (sy = [-RAIL_SPAN/2, RAIL_SPAN/2])
+        color("DimGray", 0.85)
+            translate([0, sy, -SADDLE_T])
+                rail_saddle();
+
+    // Battery tray (sitting on saddles)
+    color("OliveDrab", 0.85)
+        battery_tray();
+
+    // Battery ghost
+    %color("SaddleBrown", 0.35)
+        translate([-BATT_L/2, -BATT_W/2, TRAY_FLOOR_T])
+            cube([BATT_L, BATT_W, BATT_H]);
+
+    // Strap guides (4×, two each end)
+    for (sx = [-TRAY_OUT_L/2 + STRAP_W/2 + TRAY_WALL_T + 8,
+                TRAY_OUT_L/2 - STRAP_W/2 - TRAY_WALL_T - 8])
+    for (sy = [-1, 1])
+        color("SteelBlue", 0.75)
+            translate([sx, sy*(TRAY_OUT_W/2), TRAY_TOTAL_H + 2])
+                rotate([sy > 0 ? 0 : 180, 0, 0])
+                    strap_guide();
+}
+
+// ============================================================
+// PART 1 — BATTERY TRAY
+// ============================================================
+// Single-piece tray: flat floor, four perimeter walls, T-nut saddle
+// attachment bosses on underside, Velcro strap slots through side walls,
+// XT60 window in rear wall, balance lead channel in front wall, and
+// quick-release pull tab on front edge.
+//
+// Battery inserts from the front (−X end) — front wall is lower than
+// rear wall so the pack slides in and the rear wall stops it.
+// Velcro straps loop over the top of the pack through the side slots.
+//
+// Coordinate convention:
+//   X: along battery length (−X = front/plug-end, +X = rear/balance-end)
+//   Y: across battery width (centred, ±TRAY_OUT_W/2)
+//   Z: vertical (Z=0 = tray floor top face; −Z = underside → saddles)
+//
+// Print: floor flat on bed, PETG, 5 perims, 40% gyroid. No supports.
+module battery_tray() {
+    // Short rear wall height (XT60 connector exits here — full wall height)
+    // Front wall is lower to allow battery slide-in
+    front_wall_h = TRAY_WALL_H * 0.55;   // 55% height — battery slides over
+
+    difference() {
+        union() {
+            // ── Floor ────────────────────────────────────────────────────
+            translate([-TRAY_OUT_L/2, -TRAY_OUT_W/2, -TRAY_FLOOR_T])
+                cube([TRAY_OUT_L, TRAY_OUT_W, TRAY_FLOOR_T]);
+
+            // ── Rear wall (+X, full height) ───────────────────────────────
+            translate([TRAY_INN_L/2, -TRAY_OUT_W/2, 0])
+                cube([TRAY_WALL_T, TRAY_OUT_W, TRAY_WALL_H]);
+
+            // ── Front wall (−X, lowered for slide-in) ────────────────────
+            translate([-TRAY_INN_L/2 - TRAY_WALL_T, -TRAY_OUT_W/2, 0])
+                cube([TRAY_WALL_T, TRAY_OUT_W, front_wall_h]);
+
+            // ── Side walls (±Y) ───────────────────────────────────────────
+            for (sy = [-1, 1])
+                translate([-TRAY_OUT_L/2,
+                           sy*(TRAY_INN_W/2 + (sy>0 ? 0 : -TRAY_WALL_T)),
+                           0])
+                    cube([TRAY_OUT_L,
+                          TRAY_WALL_T,
+                          TRAY_WALL_H]);
+
+            // ── Quick-release pull tab (front wall top edge) ──────────────
+            translate([-TRAY_INN_L/2 - TRAY_WALL_T - e,
+                       -QR_TAB_W/2, front_wall_h])
+                cube([QR_TAB_T, QR_TAB_W, QR_TAB_H]);
+
+            // ── Saddle attachment bosses (underside, one per rail) ─────────
+            // Bosses drop into saddle sockets; M3 bolt through floor
+            for (sy = [-RAIL_SPAN/2, RAIL_SPAN/2])
+                translate([-SADDLE_W/2, sy - SADDLE_W/2, -TRAY_FLOOR_T - SADDLE_T/2])
+                    cube([SADDLE_W, SADDLE_W, SADDLE_T/2 + e]);
+        }
+
+        // ── Battery cavity (hollow interior) ──────────────────────────────
+        translate([-TRAY_INN_L/2, -TRAY_INN_W/2, -e])
+            cube([TRAY_INN_L, TRAY_INN_W, TRAY_WALL_H + 2*e]);
+
+        // ── XT60 connector window (rear wall) ─────────────────────────────
+        // Centred on rear wall, low position so cable exits cleanly
+        translate([TRAY_INN_L/2 - e, -XT60_W/2, XT60_OFFSET_Z])
+            cube([TRAY_WALL_T + 2*e, XT60_W, XT60_H]);
+
+        // ── Balance lead channel (front wall) ─────────────────────────────
+        // Wide slot for 6S balance lead (7-pin JST-XH ribbon)
+        translate([-TRAY_INN_L/2 - TRAY_WALL_T - e,
+                   -BAL_W/2, BAL_OFFSET_Z])
+            cube([TRAY_WALL_T + 2*e, BAL_W, BAL_H]);
+
+        // ── Velcro strap slots (side walls, 2 pairs) ──────────────────────
+        // Pair A: near front end (−X), Pair B: near rear end (+X)
+        // Each slot runs through the wall in Y direction
+        for (sx = [-TRAY_INN_L/2 + STRAP_W*0.5 + 10,
+                    TRAY_INN_L/2 - STRAP_W*0.5 - 10])
+        for (sy = [-1, 1]) {
+            translate([sx - STRAP_W/2,
+                       sy*(TRAY_INN_W/2) - (sy > 0 ? TRAY_WALL_T + e : -e),
+                       TRAY_WALL_H * 0.35])
+                cube([STRAP_W, TRAY_WALL_T + 2*e, STRAP_T]);
+        }
+
+        // ── QR tab finger-loop hole ────────────────────────────────────────
+        translate([-TRAY_INN_L/2 - TRAY_WALL_T/2,
+                   0, front_wall_h + QR_TAB_H * 0.55])
+            rotate([0, 90, 0])
+                cylinder(d = QR_HOLE_D, h = QR_TAB_T + 2*e, center = true);
+
+        // ── Saddle bolt holes (M3 through floor into saddle boss) ─────────
+        for (sy = [-RAIL_SPAN/2, RAIL_SPAN/2])
+            translate([0, sy, -TRAY_FLOOR_T - e])
+                cylinder(d = M3_D, h = TRAY_FLOOR_T + 2*e);
+
+        // ── Floor lightening grid (non-structural area) ───────────────────
+        // 2D grid of pockets reduces weight without weakening battery support
+        for (gx = [-40, 0, 40])
+        for (gy = [-12, 12])
+            translate([gx, gy, -TRAY_FLOOR_T - e])
+                cylinder(d = 14, h = TRAY_FLOOR_T - 1.5 + e);
+
+        // ── Inner corner chamfers (battery slide-in guidance) ─────────────
+        // 45° chamfers at bottom-front inner corners
+        translate([-TRAY_INN_L/2, -TRAY_INN_W/2 - e, -e])
+            rotate([0, 0, 45])
+                cube([4, 4, TRAY_WALL_H * 0.3 + e]);
+        translate([-TRAY_INN_L/2, TRAY_INN_W/2 + e, -e])
+            rotate([0, 0, -45])
+                cube([4, 4, TRAY_WALL_H * 0.3 + e]);
+    }
+}
+
+// ============================================================
+// PART 2 — RAIL SADDLE
+// ============================================================
+// T-nut foot that clamps to the top face of a 2020 T-slot rail.
+// Battery tray boss drops into saddle socket; M3 bolt through tray
+// floor and saddle body locks everything together.
+// M3 thumbscrew through side of saddle body grips the rail T-groove
+// (same thumbscrew interface as all other SaltyLab rail brackets).
+//
+// Saddle sits on top of rail (no T-nut tongue needed — saddle clamps
+// from the top using a T-nut inserted into the rail T-groove from the
+// end).  Low profile keeps battery CoG as low as possible.
+//
+// Print: flat base on bed, PETG, 5 perims, 50% gyroid.
+module rail_saddle() {
+    sock_d = SADDLE_W - 4;   // tray boss socket diameter
+
+    difference() {
+        union() {
+            // ── Main saddle body ──────────────────────────────────────────
+            translate([-SADDLE_W/2, -SADDLE_W/2, 0])
+                cube([SADDLE_W, SADDLE_W, SADDLE_T]);
+
+            // ── T-nut tongue (enters rail T-groove from above) ────────────
+            translate([-TNUT_W/2, -TNUT_L/2, -SLOT_NECK_H])
+                cube([TNUT_W, TNUT_L, SLOT_NECK_H + e]);
+
+            // ── T-nut inner body (locks in groove) ────────────────────────
+            translate([-TNUT_W/2, -TNUT_L/2, -SLOT_NECK_H - (TNUT_H - SLOT_NECK_H)])
+                cube([TNUT_W, TNUT_L, TNUT_H - SLOT_NECK_H + e]);
+        }
+
+        // ── Rail channel clearance (bottom of saddle straddles rail) ──────
+        // Saddle body has a channel that sits over the rail top face
+        translate([-RAIL_W/2 - e, -SADDLE_W/2 - e, -e])
+            cube([RAIL_W + 2*e, SADDLE_W + 2*e, 2.0]);
+
+        // ── M3 clamp bolt bore (through saddle body into T-nut) ───────────
+        translate([0, 0, -SLOT_NECK_H - TNUT_H - e])
+            cylinder(d = TNUT_BOLT_D, h = SADDLE_T + TNUT_H + 2*e);
+
+        // ── M3 hex nut pocket (top face of saddle for thumbscrew) ─────────
+        translate([0, 0, SADDLE_T - TNUT_NUT_H - 0.5])
+            cylinder(d = TNUT_NUT_AF / cos(30),
+                     h = TNUT_NUT_H + 0.6, $fn = 6);
+
+        // ── Tray boss socket (top face of saddle, tray boss nests here) ───
+        // Cylindrical socket receives tray underside boss; M3 bolt centres
+        translate([0, 0, SADDLE_T - 3])
+            cylinder(d = sock_d + 0.4, h = 3 + e);
+
+        // ── M3 tray bolt bore (vertical, through saddle top) ──────────────
+        translate([0, 0, SADDLE_T - 3 - e])
+            cylinder(d = M3_D, h = SADDLE_T + e);
+
+        // ── Anti-slip pad recess (bottom face, optional rubber adhesive) ──
+        translate([0, 0, -e])
+            cylinder(d = SADDLE_W - 8, h = SADDLE_PAD_T + e);
+
+        // ── Lightening pockets ─────────────────────────────────────────────
+        for (lx = [-1, 1], ly = [-1, 1])
+            translate([lx*8, ly*8, -e])
+                cylinder(d = 5, h = SADDLE_T - 3 - 1 + e);
+    }
+}
+
+// ============================================================
+// PART 3 — STRAP GUIDE
+// ============================================================
+// Snap-on guide that sits on top of tray wall at each strap slot,
+// directing the 25 mm Velcro strap from the side slot up and over
+// the battery top.  Four per tray, one at each slot exit.
+// Curved lip prevents strap from cutting into PETG wall edge.
+// Push-fit onto tray wall top; no fasteners required.
+//
+// Print: flat base on bed, PETG, 3 perims, 20% infill.
+module strap_guide() {
+    strap_w_clr = STRAP_W + 0.5;   // strap slot with clearance
+    lip_r       = 3.0;              // guide lip radius
+
+    difference() {
+        union() {
+            // ── Body (sits on tray wall top edge) ─────────────────────────
+            translate([-GUIDE_OD/2, 0, 0])
+                cube([GUIDE_OD, GUIDE_T, GUIDE_BODY_H]);
+
+            // ── Curved guide lip (top of body, strap bends around this) ───
+            translate([0, GUIDE_T/2, GUIDE_BODY_H])
+                rotate([0, 90, 0])
+                    cylinder(r = lip_r, h = GUIDE_OD, center = true);
+
+            // ── Wall engagement tabs (snap over tray wall top) ────────────
+            for (sy = [0, -(TRAY_WALL_T + GUIDE_T)])
+                translate([-strap_w_clr/2 - 3, sy - GUIDE_T, 0])
+                    cube([strap_w_clr + 6, GUIDE_T, GUIDE_BODY_H * 0.4]);
+        }
+
+        // ── Strap slot (through body) ──────────────────────────────────────
+        translate([-strap_w_clr/2, -e, -e])
+            cube([strap_w_clr, GUIDE_T + 2*e, GUIDE_BODY_H + 2*e]);
+
+        // ── Wall clearance slot (body slides over tray wall) ──────────────
+        translate([-strap_w_clr/2 - 3 - e,
+                   -TRAY_WALL_T - GUIDE_T, -e])
+            cube([strap_w_clr + 6 + 2*e,
+                  TRAY_WALL_T, GUIDE_BODY_H * 0.4 + 2*e]);
+
+        // ── Lightening pockets on side faces ──────────────────────────────
+        for (lx = [-GUIDE_OD/4, GUIDE_OD/4])
+            translate([lx, GUIDE_T/2, GUIDE_BODY_H/2])
+                cube([6, GUIDE_T + 2*e, GUIDE_BODY_H * 0.5], center = true);
+    }
+}

chassis/cable_tray.scad

@@ -0,0 +1,410 @@
+// ============================================================
+// Cable Management Tray — Issue #628
+// Agent   : sl-mechanical
+// Date    : 2026-03-15
+// Part catalogue:
+//   1. tray_body     — under-plate tray with snap-in cable channels, Velcro
+//                      tie-down slots every 40 mm, pass-through holes, label slots
+//   2. tnut_bracket  — 2020 T-nut rail mount bracket (×2, slide under tray)
+//   3. channel_clip  — snap-in divider clip separating power / signal / servo zones
+//   4. cover_panel   — hinged snap-on lid (living-hinge PETG flexure strip)
+//   5. cable_saddle  — individual cable saddle / strain-relief clip (×n)
+//
+// BOM:
+//   4 × M5×10 BHCS + M5 T-nuts    (tnut_bracket × 2 to rail)
+//   4 × M3×8  SHCS                (tnut_bracket to tray body)
+//   n × 100 mm Velcro tie-down strips (through 6×2 mm slots, every 40 mm)
+//
+// Cable channel layout (X axis, inside tray):
+//   Zone A — Power  (2S–6S LiPo, XT60/XT30): 20 mm wide, 14 mm deep
+//   Zone B — Signal (JST-SH, PWM, I2C, UART): 14 mm wide, 10 mm deep
+//   Zone C — Servo  (JST-PH, thick servo leads): 14 mm wide, 12 mm deep
+//   Divider walls: 2.5 mm thick between zones
+//
+// Print settings (PETG):
+//   tray_body / tnut_bracket / channel_clip : 5 perimeters, 40 % gyroid, no supports
+//   cover_panel                             : 3 perimeters, 20 % gyroid, no supports
+//                                             (living-hinge — print flat, thin strip flexes)
+//   cable_saddle                            : 3 perimeters, 30 % gyroid, no supports
+//
+// Export commands:
+//   openscad -D 'RENDER="tray_body"'     -o tray_body.stl     cable_tray.scad
+//   openscad -D 'RENDER="tnut_bracket"'  -o tnut_bracket.stl  cable_tray.scad
+//   openscad -D 'RENDER="channel_clip"'  -o channel_clip.stl  cable_tray.scad
+//   openscad -D 'RENDER="cover_panel"'   -o cover_panel.stl   cable_tray.scad
+//   openscad -D 'RENDER="cable_saddle"'  -o cable_saddle.stl  cable_tray.scad
+//   openscad -D 'RENDER="assembly"'      -o assembly.png      cable_tray.scad
+// ============================================================
+
+RENDER = "assembly"; // tray_body | tnut_bracket | channel_clip | cover_panel | cable_saddle | assembly
+
+$fn = 48;
+EPS = 0.01;
+
+// ── 2020 rail constants ──────────────────────────────────────
+RAIL_W      = 20.0;
+TNUT_W      =  9.8;
+TNUT_H      =  5.5;
+TNUT_L      = 12.0;
+SLOT_NECK_H =  3.2;
+M5_D        =  5.2;
+M5_HEAD_D   =  9.5;
+M5_HEAD_H   =  4.0;
+
+// ── Tray geometry ────────────────────────────────────────────
+TRAY_L      = 280.0;  // length along rail (7 × 40 mm tie-down pitch)
+TRAY_W      =  60.0;  // width across rail (covers standard 40 mm rail pair)
+TRAY_WALL   =   2.5;  // side / floor wall thickness
+TRAY_DEPTH  =  18.0;  // interior depth (tallest zone + wall)
+
+// Cable channel zones (widths must sum to TRAY_W - 2*TRAY_WALL - 2*DIV_T)
+DIV_T       =   2.5;  // divider wall thickness
+ZONE_A_W    =  20.0;  // Power
+ZONE_A_D    =  14.0;
+ZONE_B_W    =  14.0;  // Signal
+ZONE_B_D    =  10.0;
+ZONE_C_W    =  14.0;  // Servo
+ZONE_C_D    =  12.0;
+// Total inner width used: ZONE_A_W + ZONE_B_W + ZONE_C_W + 2*DIV_T = 55 mm < TRAY_W - 2*TRAY_WALL = 55 mm ✓
+
+// Tie-down slots (Velcro strips)
+TIEDOWN_PITCH = 40.0;
+TIEDOWN_W   =   6.0;  // slot width (fits 6 mm wide Velcro)
+TIEDOWN_T   =   2.2;  // slot through-thickness (floor)
+TIEDOWN_CNT = 7;      // 7 positions along tray
+
+// Pass-through holes in floor
+PASSTHRU_D  =  12.0;  // circular grommet-compatible pass-through
+PASSTHRU_CNT = 3;     // one per zone, at tray mid-length
+
+// Label slots (rear outer wall)
+LABEL_W     =  24.0;
+LABEL_H     =   8.0;
+LABEL_T     =   1.0;  // depth from outer face
+
+// Snap ledge for cover
+SNAP_LEDGE_H =  2.5;
+SNAP_LEDGE_D =  1.5;
+
+// ── T-nut bracket ────────────────────────────────────────────
+BKT_L       =  60.0;
+BKT_W       =  TRAY_W;
+BKT_T       =   6.0;
+BOLT_PITCH  =  40.0;
+M3_D        =   3.2;
+M3_HEAD_D   =   6.0;
+M3_HEAD_H   =   3.0;
+M3_NUT_W    =   5.5;
+M3_NUT_H    =   2.4;
+
+// ── Cover panel ──────────────────────────────────────────────
+CVR_T       =   1.8;  // panel thickness
+HINGE_T     =   0.6;  // living-hinge strip thickness (printed in PETG)
+HINGE_W     =   3.0;  // hinge strip width (flexes easily)
+SNAP_HOOK_H =   3.5;  // snap hook height
+SNAP_HOOK_T =   2.2;
+
+// ── Cable saddle ─────────────────────────────────────────────
+SAD_W       =  12.0;
+SAD_H       =   8.0;
+SAD_T       =   2.5;
+SAD_BORE_D  =   7.0;  // cable bundle bore
+SAD_CLIP_T  =   1.6;  // snap arm thickness
+
+// ── Utilities ────────────────────────────────────────────────
+module chamfer_cube(size, ch=1.0) {
+    hull() {
+        translate([ch, ch, 0])   cube([size[0]-2*ch, size[1]-2*ch, EPS]);
+        translate([0, 0, ch])    cube(size - [0, 0, ch]);
+    }
+}
+
+module hex_pocket(af, depth) {
+    cylinder(d=af/cos(30), h=depth, $fn=6);
+}
+
+// ── Part 1: tray_body ───────────────────────────────────────
+module tray_body() {
+    difference() {
+        // Outer shell
+        union() {
+            chamfer_cube([TRAY_L, TRAY_W, TRAY_DEPTH + TRAY_WALL], ch=1.5);
+
+            // Snap ledge along top of both long walls (for cover_panel)
+            for (y = [-SNAP_LEDGE_D, TRAY_W])
+                translate([0, y, TRAY_DEPTH])
+                    cube([TRAY_L, TRAY_WALL + SNAP_LEDGE_D, SNAP_LEDGE_H]);
+        }
+
+        // Interior cavity
+        translate([TRAY_WALL, TRAY_WALL, TRAY_WALL])
+            cube([TRAY_L - 2*TRAY_WALL, TRAY_W - 2*TRAY_WALL,
+                  TRAY_DEPTH + EPS]);
+
+        // ── Zone dividers (subtract from solid to leave walls) ──
+        // Zone A (Power) inner floor cut — full depth A
+        translate([TRAY_WALL, TRAY_WALL, TRAY_WALL + (TRAY_DEPTH - ZONE_A_D)])
+            cube([TRAY_L - 2*TRAY_WALL, ZONE_A_W, ZONE_A_D + EPS]);
+
+        // Zone B (Signal) inner floor cut
+        translate([TRAY_WALL, TRAY_WALL + ZONE_A_W + DIV_T,
+                   TRAY_WALL + (TRAY_DEPTH - ZONE_B_D)])
+            cube([TRAY_L - 2*TRAY_WALL, ZONE_B_W, ZONE_B_D + EPS]);
+
+        // Zone C (Servo) inner floor cut
+        translate([TRAY_WALL, TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W + DIV_T,
+                   TRAY_WALL + (TRAY_DEPTH - ZONE_C_D)])
+            cube([TRAY_L - 2*TRAY_WALL, ZONE_C_W, ZONE_C_D + EPS]);
+
+        // ── Velcro tie-down slots (floor, every 40 mm) ──────────
+        for (i = [0:TIEDOWN_CNT-1]) {
+            x = TRAY_WALL + 20 + i * TIEDOWN_PITCH - TIEDOWN_W/2;
+            // Zone A slot
+            translate([x, TRAY_WALL + 2, -EPS])
+                cube([TIEDOWN_W, ZONE_A_W - 4, TRAY_WALL + 2*EPS]);
+            // Zone B slot
+            translate([x, TRAY_WALL + ZONE_A_W + DIV_T + 2, -EPS])
+                cube([TIEDOWN_W, ZONE_B_W - 4, TRAY_WALL + 2*EPS]);
+            // Zone C slot
+            translate([x, TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W + DIV_T + 2, -EPS])
+                cube([TIEDOWN_W, ZONE_C_W - 4, TRAY_WALL + 2*EPS]);
+        }
+
+        // ── Pass-through holes in floor (centre of each zone at mid-length) ──
+        mid_x = TRAY_L / 2;
+        // Zone A
+        translate([mid_x, TRAY_WALL + ZONE_A_W/2, -EPS])
+            cylinder(d=PASSTHRU_D, h=TRAY_WALL + 2*EPS);
+        // Zone B
+        translate([mid_x, TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W/2, -EPS])
+            cylinder(d=PASSTHRU_D, h=TRAY_WALL + 2*EPS);
+        // Zone C
+        translate([mid_x, TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W + DIV_T + ZONE_C_W/2, -EPS])
+            cylinder(d=PASSTHRU_D, h=TRAY_WALL + 2*EPS);
+
+        // ── Label slots on front wall (y = 0) — one per zone ────
+        zone_ctrs = [TRAY_WALL + ZONE_A_W/2,
+                     TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W/2,
+                     TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W + DIV_T + ZONE_C_W/2];
+        label_z = TRAY_WALL + 2;
+        for (yc = zone_ctrs)
+            translate([TRAY_L/2 - LABEL_W/2, -EPS, label_z])
+                cube([LABEL_W, LABEL_T + EPS, LABEL_H]);
+
+        // ── M3 bracket bolt holes in floor (4 corners) ──────────
+        for (x = [20, TRAY_L - 20])
+            for (y = [TRAY_W/4, 3*TRAY_W/4])
+                translate([x, y, -EPS])
+                    cylinder(d=M3_D, h=TRAY_WALL + 2*EPS);
+
+        // ── Channel clip snap sockets (top of each divider, every 80 mm) ──
+        for (i = [0:2]) {
+            cx = 40 + i * 80;
+            for (dy = [ZONE_A_W, ZONE_A_W + DIV_T + ZONE_B_W])
+                translate([cx - 3, TRAY_WALL + dy - 1, TRAY_DEPTH - 4])
+                    cube([6, DIV_T + 2, 4 + EPS]);
+        }
+    }
+
+    // ── Divider walls (positive geometry) ───────────────────
+    // Wall between Zone A and Zone B
+    translate([TRAY_WALL, TRAY_WALL + ZONE_A_W, TRAY_WALL])
+        cube([TRAY_L - 2*TRAY_WALL, DIV_T,
+              TRAY_DEPTH - ZONE_A_D]);  // partial height — lower in A zone
+
+    // Wall between Zone B and Zone C
+    translate([TRAY_WALL, TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W, TRAY_WALL])
+        cube([TRAY_L - 2*TRAY_WALL, DIV_T,
+              TRAY_DEPTH - ZONE_B_D]);
+}
+
+// ── Part 2: tnut_bracket ────────────────────────────────────
+module tnut_bracket() {
+    difference() {
+        chamfer_cube([BKT_L, BKT_W, BKT_T], ch=1.5);
+
+        // M5 T-nut holes (2 per bracket, on rail centreline)
+        for (x = [BKT_L/2 - BOLT_PITCH/2, BKT_L/2 + BOLT_PITCH/2]) {
+            translate([x, BKT_W/2, -EPS]) {
+                cylinder(d=M5_D, h=BKT_T + 2*EPS);
+                cylinder(d=M5_HEAD_D, h=M5_HEAD_H + EPS);
+            }
+            translate([x - TNUT_L/2, BKT_W/2 - TNUT_W/2, BKT_T - TNUT_H])
+                cube([TNUT_L, TNUT_W, TNUT_H + EPS]);
+        }
+
+        // M3 tray-attachment holes (4 corners)
+        for (x = [10, BKT_L - 10])
+            for (y = [10, BKT_W - 10]) {
+                translate([x, y, -EPS])
+                    cylinder(d=M3_D, h=BKT_T + 2*EPS);
+                // M3 hex nut captured pocket (from top)
+                translate([x, y, BKT_T - M3_NUT_H - 0.2])
+                    hex_pocket(M3_NUT_W + 0.3, M3_NUT_H + 0.3);
+            }
+
+        // Weight relief
+        translate([15, 8, -EPS])
+            cube([BKT_L - 30, BKT_W - 16, BKT_T/2]);
+    }
+}
+
+// ── Part 3: channel_clip ────────────────────────────────────
+// Snap-in clip that locks into divider-wall snap sockets;
+// holds individual bundles in their zone and acts as colour-coded zone marker.
+module channel_clip() {
+    clip_body_w = 6.0;
+    clip_body_h = DIV_T + 4.0;
+    clip_body_t = 8.0;
+    tab_h = 3.5;
+    tab_w = 2.5;
+
+    difference() {
+        union() {
+            // Body spanning divider
+            cube([clip_body_t, clip_body_w, clip_body_h]);
+
+            // Snap tabs (bottom, straddle divider)
+            for (s = [0, clip_body_w - tab_w])
+                translate([clip_body_t/2 - 1, s, -tab_h])
+                    cube([2, tab_w, tab_h + 1]);
+        }
+
+        // Cable radius slot on each face
+        translate([-EPS, clip_body_w/2, clip_body_h * 0.6])
+            rotate([0, 90, 0])
+                cylinder(d=5.0, h=clip_body_t + 2*EPS);
+
+        // Snap tab undercut for flex
+        for (s = [0, clip_body_w - tab_w])
+            translate([clip_body_t/2 - 2, s - EPS, -tab_h + 1.5])
+                cube([4, tab_w + 2*EPS, 1.5]);
+    }
+}
+
+// ── Part 4: cover_panel ─────────────────────────────────────
+// Flat snap-on lid with living-hinge along one long edge.
+// Print flat; PETG living hinge flexes ~90° to snap onto tray.
+module cover_panel() {
+    total_w = TRAY_W + 2 * SNAP_HOOK_T;
+
+    difference() {
+        union() {
+            // Main panel
+            cube([TRAY_L, TRAY_W, CVR_T]);
+
+            // Living hinge strip along back edge (thin, flexes)
+            translate([0, TRAY_W - EPS, 0])
+                cube([TRAY_L, HINGE_W, HINGE_T]);
+
+            // Snap hooks along front edge (clips under tray snap ledge)
+            for (x = [20, TRAY_L/2 - 20, TRAY_L/2 + 20, TRAY_L - 20])
+                translate([x - SNAP_HOOK_T/2, -SNAP_HOOK_H + EPS, 0])
+                    difference() {
+                        cube([SNAP_HOOK_T, SNAP_HOOK_H, CVR_T + 1.5]);
+                        // Hook nose chamfer
+                        translate([-EPS, -EPS, CVR_T])
+                            rotate([0, 0, 0])
+                                cube([SNAP_HOOK_T + 2*EPS, 1.5, 1.5]);
+                    }
+        }
+
+        // Ventilation slots (3 rows × 6 slots)
+        for (row = [0:2])
+            for (col = [0:5]) {
+                sx = 20 + col * 40 + row * 10;
+                sy = 10 + row * 12;
+                if (sx + 25 < TRAY_L && sy + 6 < TRAY_W)
+                    translate([sx, sy, -EPS])
+                        cube([25, 6, CVR_T + 2*EPS]);
+            }
+
+        // Zone label windows (align with tray label slots)
+        zone_ctrs = [TRAY_WALL + ZONE_A_W/2,
+                     TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W/2,
+                     TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W + DIV_T + ZONE_C_W/2];
+        for (yc = zone_ctrs)
+            translate([TRAY_L/2 - LABEL_W/2, yc - LABEL_H/2, -EPS])
+                cube([LABEL_W, LABEL_H, CVR_T + 2*EPS]);
+    }
+}
+
+// ── Part 5: cable_saddle ────────────────────────────────────
+// Snap-in cable saddle / strain-relief clip; press-fits onto tray top edge.
+module cable_saddle() {
+    arm_gap = TRAY_WALL + 0.4;  // fits over tray wall
+    arm_len = 8.0;
+
+    difference() {
+        union() {
+            // Body
+            chamfer_cube([SAD_W, SAD_T * 2 + arm_gap, SAD_H], ch=1.0);
+
+            // Cable retaining arch
+            translate([SAD_W/2, SAD_T + arm_gap/2, SAD_H])
+                scale([1, 0.6, 1])
+                    difference() {
+                        cylinder(d=SAD_BORE_D + SAD_CLIP_T * 2, h=SAD_T);
+                        translate([0, 0, -EPS])
+                            cylinder(d=SAD_BORE_D, h=SAD_T + 2*EPS);
+                        translate([-SAD_BORE_D, 0, -EPS])
+                            cube([SAD_BORE_D * 2, SAD_BORE_D, SAD_T + 2*EPS]);
+                    }
+        }
+
+        // Slot for tray wall (negative)
+        translate([0, SAD_T, -EPS])
+            cube([SAD_W, arm_gap, arm_len + EPS]);
+
+        // M3 tie-down hole
+        translate([SAD_W/2, SAD_T + arm_gap/2, -EPS])
+            cylinder(d=M3_D, h=SAD_H + 2*EPS);
+    }
+}
+
+// ── Assembly ────────────────────────────────────────────────
+module assembly() {
+    // Tray body (open face up for visibility)
+    color("SteelBlue")
+        tray_body();
+
+    // Two T-nut brackets underneath at 1/4 and 3/4 length
+    for (bx = [TRAY_L/4 - BKT_L/2, 3*TRAY_L/4 - BKT_L/2])
+        color("DodgerBlue")
+            translate([bx, 0, -BKT_T])
+                tnut_bracket();
+
+    // Channel clips (3 per divider position, every 80 mm)
+    for (i = [0:2]) {
+        cx = 40 + i * 80;
+        // Divider A/B
+        color("Tomato", 0.8)
+            translate([cx - 4, TRAY_WALL + ZONE_A_W - 2, TRAY_DEPTH - 3])
+                channel_clip();
+        // Divider B/C
+        color("Orange", 0.8)
+            translate([cx - 4,
+                       TRAY_WALL + ZONE_A_W + DIV_T + ZONE_B_W - 2,
+                       TRAY_DEPTH - 3])
+                channel_clip();
+    }
+
+    // Cover panel (raised above tray to show interior)
+    color("LightSteelBlue", 0.5)
+        translate([0, 0, TRAY_DEPTH + SNAP_LEDGE_H + 4])
+            cover_panel();
+
+    // Cable saddles along front tray edge
+    for (x = [40, 120, 200])
+        color("SlateGray")
+            translate([x - SAD_W/2, -SAD_T * 2 - TRAY_WALL, 0])
+                cable_saddle();
+}
+
+// ── Dispatch ────────────────────────────────────────────────
+if      (RENDER == "tray_body")    tray_body();
+else if (RENDER == "tnut_bracket") tnut_bracket();
+else if (RENDER == "channel_clip") channel_clip();
+else if (RENDER == "cover_panel")  cover_panel();
+else if (RENDER == "cable_saddle") cable_saddle();
+else                               assembly();

chassis/canable_mount.scad

@@ -0,0 +1,265 @@
+// ============================================================
+// canable_mount.scad — CANable 2.0 USB-CAN Adapter Cradle
+// Issue #654 / sl-mechanical  2026-03-16
+// ============================================================
+// Snap-fit cradle for CANable 2.0 PCB (~60 × 18 × 10 mm).
+// Attaches to 2020 aluminium T-slot rail via 2× M5 T-nuts.
+//
+// Port access:
+//   USB-C port       — X− end wall cutout (connector protrudes through)
+//   CAN terminal     — X+ end wall cutout (CANH / CANL / GND wire exit)
+//   LED status window— slot in Y+ side wall, PCB top-face LEDs visible
+//
+// Retention: snap-fit cantilever lips on both side walls (PETG flex).
+// Cable strain relief: zip-tie boss pair on X+ shelf (CAN wires).
+//
+// ⚠  VERIFY WITH CALIPERS BEFORE PRINTING:
+//    PCB_L, PCB_W          board outline
+//    USBC_W, USBC_H        USB-C shell at X− edge
+//    TERM_W, TERM_H        3-pos terminal block at X+ edge
+//    LED_X_CTR, LED_WIN_W  LED window position on Y+ wall
+//
+// Print settings (PETG):
+//   3 perimeters, 40 % gyroid infill, no supports, 0.2 mm layer
+//   Print orientation: open face UP (as modelled)
+//
+// BOM:
+//   2 × M5×10 BHCS  +  2 × M5 slide-in T-nut  (2020 rail)
+//
+// Export commands:
+//   openscad -D 'RENDER="mount"'    -o canable_mount.stl    canable_mount.scad
+//   openscad -D 'RENDER="assembly"' -o canable_assembly.png canable_mount.scad
+// ============================================================
+
+RENDER = "assembly"; // mount | assembly
+
+$fn = 48;
+EPS = 0.01;
+
+// ── ⚠ Verify before printing ─────────────────────────────────
+// CANable 2.0 PCB
+PCB_L    = 60.0;   // board length  (X: USB-C end → terminal end)
+PCB_W    = 18.0;   // board width   (Y)
+PCB_T    =  1.6;   // board thickness
+COMP_H   =  8.5;   // tallest component above board (USB-C shell ≈ 3.5 mm;
+                   //   terminal block ≈ 8.5 mm)
+
+// USB-C connector (at X− end face of PCB)
+USBC_W   =  9.5;   // connector outer width
+USBC_H   =  3.8;   // connector outer height above board surface
+USBC_Z0  =  0.0;   // connector bottom offset above board surface
+
+// CAN screw-terminal block (at X+ end face, 3-pos 5.0 mm pitch)
+TERM_W   = 16.0;   // terminal block span (3 × 5 mm + housing)
+TERM_H   =  9.0;   // terminal block height above board surface
+TERM_Z0  =  0.5;   // terminal bottom offset above board surface
+
+// Status LED window (LEDs near USB-C end on PCB top face)
+//   Rectangular slot cut in Y+ side wall — LEDs visible from the side
+LED_X_CTR  = 11.0;  // LED zone centre measured from PCB X− edge
+LED_WIN_W  = 14.0;  // window width (X)
+LED_WIN_H  =  5.5;  // window height (Z) — opens top portion of side wall
+
+// ── Cradle geometry ──────────────────────────────────────────
+WALL_T   = 2.5;    // side/end wall thickness
+FLOOR_T  = 4.0;    // floor plate thickness (accommodates M5 BHCS head pocket)
+CL_SIDE  = 0.30;   // Y clearance per side (total 0.6 mm play)
+CL_END   = 0.40;   // X clearance per end
+
+// Interior cavity
+INN_W    = PCB_W + 2*CL_SIDE;          // Y span
+INN_L    = PCB_L + 2*CL_END;           // X span
+INN_H    = PCB_T + COMP_H + 1.2;       // Z height (board + tallest comp + margin)
+
+// Outer body
+OTR_W    = INN_W  + 2*WALL_T;          // Y
+OTR_L    = INN_L  + 2*WALL_T;          // X
+OTR_H    = FLOOR_T + INN_H;            // Z
+
+// PCB reference origin within body (lower-left corner of board)
+PCB_X0   = WALL_T + CL_END;            // board X start inside body
+PCB_Y0   = WALL_T + CL_SIDE;           // board Y start inside body
+PCB_Z0   = FLOOR_T;                    // board bottom sits on floor
+
+// ── Snap-fit lips ─────────────────────────────────────────────
+// Cantilever ledge on inner face of each side wall, at PCB-top Z.
+// Tapered (chamfered) entry guides PCB in from above.
+SNAP_IN  = 0.8;    // how far inward ledge protrudes over PCB edge
+SNAP_T   = 1.2;    // snap-arm thickness (thin for PETG flex)
+SNAP_H   = 4.0;    // cantilever arm height (root at OTR_H, tip near PCB_Z0+PCB_T)
+SNAP_L   = 18.0;   // arm length along X (centred on PCB, shorter = more flex)
+// Snap on Y− wall protrudes in +Y direction; Y+ wall protrudes in −Y direction
+
+// ── M5 T-nut mount (2020 rail) ────────────────────────────────
+M5_D       =  5.3;   // M5 bolt clearance bore
+M5_HEAD_D  =  9.5;   // M5 BHCS head pocket diameter (from bottom face)
+M5_HEAD_H  =  3.0;   // BHCS head pocket depth
+M5_SPAC    = 20.0;   // bolt spacing along X (centred on cradle)
+// Standard M5 slide-in T-nuts used — no T-nut pocket moulded in.
+
+// ── Cable strain relief ───────────────────────────────────────
+// Two zip-tie anchor bosses on a shelf inside the X+ end, straddling
+// the CAN terminal wires.
+SR_BOSS_OD =  7.0;   // boss outer diameter
+SR_BOSS_H  =  5.5;   // boss height above floor
+SR_SLOT_W  =  3.5;   // zip-tie slot width
+SR_SLOT_T  =  2.2;   // zip-tie slot through-height
+// Boss Y positions (straddle terminal block)
+SR_Y1      = WALL_T + INN_W * 0.25;
+SR_Y2      = WALL_T + INN_W * 0.75;
+SR_X       = OTR_L - WALL_T - SR_BOSS_OD/2 - 2.5;  // just inside X+ end wall
+
+// ─────────────────────────────────────────────────────────────
+module canable_mount() {
+    difference() {
+        // ── Outer solid body ──────────────────────────────────
+        union() {
+            cube([OTR_L, OTR_W, OTR_H]);
+
+            // ── Snap cantilever arms on Y− wall (protrude inward +Y) ──
+            // Arms hang down from top of Y− wall inner face.
+            // Root is flush with inner face (Y = WALL_T); tip at PCB level.
+            translate([OTR_L/2 - SNAP_L/2, WALL_T - SNAP_T, OTR_H - SNAP_H])
+                cube([SNAP_L, SNAP_T, SNAP_H]);
+
+            // ── Snap cantilever arms on Y+ wall (protrude inward −Y) ──
+            translate([OTR_L/2 - SNAP_L/2, OTR_W - WALL_T, OTR_H - SNAP_H])
+                cube([SNAP_L, SNAP_T, SNAP_H]);
+
+            // ── Cable strain relief bosses (X+ end, inside) ────
+            for (sy = [SR_Y1, SR_Y2])
+                translate([SR_X, sy, 0])
+                    cylinder(d=SR_BOSS_OD, h=SR_BOSS_H);
+        }
+
+        // ── Interior cavity ───────────────────────────────────
+        translate([WALL_T, WALL_T, FLOOR_T])
+            cube([INN_L, INN_W, INN_H + EPS]);
+
+        // ── USB-C cutout — X− end wall ────────────────────────
+        // Centred on PCB width; opened from board surface upward
+        translate([-EPS,
+                   PCB_Y0 + PCB_W/2 - (USBC_W + 1.5)/2,
+                   PCB_Z0 + USBC_Z0 - 0.5])
+            cube([WALL_T + 2*EPS, USBC_W + 1.5, USBC_H + 2.5]);
+
+        // ── CAN terminal cutout — X+ end wall ─────────────────
+        // Full terminal width + 2 mm margin for screwdriver access;
+        // height clears terminal block + wire bend radius
+        translate([OTR_L - WALL_T - EPS,
+                   PCB_Y0 + PCB_W/2 - (TERM_W + 2.0)/2,
+                   PCB_Z0 + TERM_Z0 - 0.5])
+            cube([WALL_T + 2*EPS, TERM_W + 2.0, TERM_H + 5.0]);
+
+        // ── LED status window — Y+ side wall ─────────────────
+        // Rectangular slot; LEDs at top-face of PCB are visible through it
+        translate([PCB_X0 + LED_X_CTR - LED_WIN_W/2,
+                   OTR_W - WALL_T - EPS,
+                   OTR_H - LED_WIN_H])
+            cube([LED_WIN_W, WALL_T + 2*EPS, LED_WIN_H + EPS]);
+
+        // ── M5 BHCS head pockets (from bottom face of floor) ──
+        for (mx = [OTR_L/2 - M5_SPAC/2, OTR_L/2 + M5_SPAC/2])
+            translate([mx, OTR_W/2, -EPS]) {
+                // Clearance bore through full floor
+                cylinder(d=M5_D, h=FLOOR_T + 2*EPS);
+                // BHCS head pocket from bottom face
+                cylinder(d=M5_HEAD_D, h=M5_HEAD_H + EPS);
+            }
+
+        // ── Snap-arm ledge slot — Y− arm (hollow out to thin arm) ──
+        // Arm is SNAP_T thick; cut away material behind arm
+        translate([OTR_L/2 - SNAP_L/2 - EPS, EPS, OTR_H - SNAP_H])
+            cube([SNAP_L + 2*EPS, WALL_T - SNAP_T - EPS, SNAP_H + EPS]);
+
+        // ── Snap-arm ledge slot — Y+ arm ──────────────────────
+        translate([OTR_L/2 - SNAP_L/2 - EPS, OTR_W - WALL_T + SNAP_T, OTR_H - SNAP_H])
+            cube([SNAP_L + 2*EPS, WALL_T - SNAP_T - EPS, SNAP_H + EPS]);
+
+        // ── Snap-arm inward ledge notch (entry chamfer removed) ─
+        // Chamfer top of snap arm so PCB slides in easily
+        // Y− arm: chamfer on upper-inner edge → 45° wedge on +Y/+Z corner
+        translate([OTR_L/2 - SNAP_L/2 - EPS,
+                   WALL_T - SNAP_T - EPS,
+                   OTR_H - SNAP_IN])
+            rotate([0, 0, 0])
+            rotate([45, 0, 0])
+                cube([SNAP_L + 2*EPS, SNAP_IN * 1.5, SNAP_IN * 1.5]);
+
+        // Y+ arm: chamfer on upper-inner edge
+        translate([OTR_L/2 - SNAP_L/2 - EPS,
+                   OTR_W - WALL_T + SNAP_T - SNAP_IN * 1.5 + EPS,
+                   OTR_H - SNAP_IN])
+            rotate([45, 0, 0])
+                cube([SNAP_L + 2*EPS, SNAP_IN * 1.5, SNAP_IN * 1.5]);
+
+        // ── Snap ledge cutout on Y− arm inner tip ─────────────
+        // Creates inward nub: remove top portion of arm inner tip
+        // leaving bottom SNAP_IN height as the retaining ledge
+        translate([OTR_L/2 - SNAP_L/2 - EPS,
+                   WALL_T - SNAP_T - EPS,
+                   PCB_Z0 + PCB_T + SNAP_IN])
+            cube([SNAP_L + 2*EPS, SNAP_T + 2*EPS,
+                  OTR_H - (PCB_Z0 + PCB_T + SNAP_IN) + EPS]);
+
+        // ── Snap ledge cutout on Y+ arm inner tip ─────────────
+        translate([OTR_L/2 - SNAP_L/2 - EPS,
+                   OTR_W - WALL_T - EPS,
+                   PCB_Z0 + PCB_T + SNAP_IN])
+            cube([SNAP_L + 2*EPS, SNAP_T + 2*EPS,
+                  OTR_H - (PCB_Z0 + PCB_T + SNAP_IN) + EPS]);
+
+        // ── Zip-tie slots through strain relief bosses ─────────
+        for (sy = [SR_Y1, SR_Y2])
+            translate([SR_X, sy,
+                       SR_BOSS_H/2 - SR_SLOT_T/2])
+                rotate([0, 90, 0])
+                    cube([SR_SLOT_T, SR_SLOT_W,
+                          SR_BOSS_OD + 2*EPS],
+                         center=true);
+
+        // ── Weight relief pocket in floor (underside) ─────────
+        translate([WALL_T + 8, WALL_T + 3, -EPS])
+            cube([OTR_L - 2*WALL_T - 16, OTR_W - 2*WALL_T - 6,
+                  FLOOR_T - 1.5 + EPS]);
+    }
+}
+
+// ── Assembly preview ─────────────────────────────────────────
+if (RENDER == "assembly") {
+    color("DimGray", 0.93) canable_mount();
+
+    // Phantom PCB
+    color("MidnightBlue", 0.35)
+        translate([PCB_X0, PCB_Y0, PCB_Z0])
+            cube([PCB_L, PCB_W, PCB_T]);
+
+    // Phantom component block (top of PCB)
+    color("DarkSlateGray", 0.25)
+        translate([PCB_X0, PCB_Y0, PCB_Z0 + PCB_T])
+            cube([PCB_L, PCB_W, COMP_H]);
+
+    // USB-C port highlight
+    color("Gold", 0.8)
+        translate([-1,
+                   PCB_Y0 + PCB_W/2 - USBC_W/2,
+                   PCB_Z0 + USBC_Z0])
+            cube([WALL_T + 2, USBC_W, USBC_H]);
+
+    // Terminal block highlight
+    color("Tomato", 0.7)
+        translate([OTR_L - WALL_T - 1,
+                   PCB_Y0 + PCB_W/2 - TERM_W/2,
+                   PCB_Z0 + TERM_Z0])
+            cube([WALL_T + 2, TERM_W, TERM_H]);
+
+    // LED zone highlight
+    color("LimeGreen", 0.9)
+        translate([PCB_X0 + LED_X_CTR - LED_WIN_W/2,
+                   OTR_W - WALL_T - 0.5,
+                   OTR_H - LED_WIN_H + 1])
+            cube([LED_WIN_W, 1, LED_WIN_H - 2]);
+
+} else {
+    canable_mount();
+}

chassis/charging_dock_505.scad

@@ -0,0 +1,531 @@
+// ============================================================
+// charging_dock_505.scad — 24V Charging Dock Station
+// Issue: #505  Agent: sl-mechanical  Date: 2026-03-06
+// ============================================================
+//
+// 24V upgraded dock (forked from Issue #159 5V design).
+// Robot drives forward into V-guide funnel; spring-loaded pogo pins
+// make contact with the robot receiver plate (charging_dock_receiver.scad).
+//
+// Power:   24 V / 10 A (240 W) via 2× high-current pogo pins (+/-)
+// Alignment tolerance: ±20 mm lateral (V-guide funnels to centre)
+//
+// Dock architecture (top view):
+//
+//   ┌─────────────────────────────────┐  ← back wall (robot stops here)
+//   │  PSU shelf                      │
+//   │  [PSU]         [LED ×4]         │
+//   │         [POGO+][POGO-]          │  ← pogo face (robot contact)
+//   └────\                   /────────┘
+//         \  V-guide rails  /
+//          \               /
+//           ╲             ╱  ← dock entry, ±20 mm funnel
+//
+// Components (this file):
+//   Part A — dock_base()         weighted base plate with ballast pockets
+//   Part B — back_wall()         upright back panel + pogo housing + LED bezel
+//   Part C — guide_rail(side)    V-funnel guide rail, L/R (print 2×)
+//   Part D — aruco_mount()       ArUco marker frame at dock entrance
+//   Part E — psu_bracket()       PSU retention bracket (rear of base)
+//   Part F — led_bezel()         4-LED status bezel
+//
+// Robot-side receiver → see charging_dock_receiver.scad
+//
+// Coordinate system:
+//   Z = 0 at dock floor (base plate top face)
+//   Y = 0 at back wall front face (robot approaches from +Y)
+//   X = 0 at dock centre
+//   Robot drives in -Y direction to dock.
+//
+// RENDER options:
+//   "assembly"       full dock preview (default)
+//   "base_stl"       base plate (print 1×)
+//   "back_wall_stl"  back wall + pogo housing (print 1×)
+//   "guide_rail_stl" V-guide rail (print 2×, mirror for R side)
+//   "aruco_mount_stl" ArUco marker frame (print 1×)
+//   "psu_bracket_stl" PSU mounting bracket (print 1×)
+//   "led_bezel_stl"  LED status bezel (print 1×)
+//
+// Export commands (Issue #505 24V variant):
+//   openscad charging_dock_505.scad -D 'RENDER="base_stl"'       -o dock_505_base.stl
+//   openscad charging_dock_505.scad -D 'RENDER="back_wall_stl"'  -o dock_505_back_wall.stl
+//   openscad charging_dock_505.scad -D 'RENDER="guide_rail_stl"' -o dock_505_guide_rail.stl
+//   openscad charging_dock_505.scad -D 'RENDER="aruco_mount_stl"' -o dock_505_aruco_mount.stl
+//   openscad charging_dock_505.scad -D 'RENDER="psu_bracket_stl"' -o dock_505_psu_bracket.stl
+//   openscad charging_dock_505.scad -D 'RENDER="led_bezel_stl"'  -o dock_505_led_bezel.stl
+// ============================================================
+
+$fn = 64;
+e   = 0.01;
+
+// ── Base plate dimensions ─────────────────────────────────────────────────────
+// NOTE: Enlarged for 24V PSU (IRM-240-24: 210×108×56 mm vs. IRM-30-5: 63×45×28 mm)
+BASE_W   = 340.0;    // base width  (X) — increased for larger PSU bracket
+BASE_D   = 320.0;    // base depth  (Y, extends behind and in front of back wall)
+BASE_T   =  12.0;    // base thickness
+BASE_R   =  10.0;    // corner radius
+
+// Ballast pockets (for steel hex bar / bolt weights):
+// 4× pockets in base underside, accept M20 hex nuts (30 mm AF) stacked
+BALLAST_N   = 4;
+BALLAST_W   = 32.0;   // pocket width  (hex nut AF + 2 mm)
+BALLAST_D   = 32.0;   // pocket depth
+BALLAST_T   =  8.0;   // pocket depth (≤ BASE_T/2)
+BALLAST_INSET_X = 50.0;
+BALLAST_INSET_Y = 40.0;
+
+// Floor bolt holes (M8, for bolting dock to bench/floor — optional)
+FLOOR_BOLT_D   = 8.5;
+FLOOR_BOLT_INSET_X = 30.0;
+FLOOR_BOLT_INSET_Y = 25.0;
+
+// ── Back wall (upright panel) ─────────────────────────────────────────────────
+WALL_W   = 250.0;   // wall width (X) — same as guide entry span
+WALL_H   =  85.0;   // wall height (Z)
+WALL_T   =  10.0;   // wall thickness (Y)
+
+// Back wall Y position relative to base rear edge
+// Wall sits at Y=0 (its front face); base extends behind it (-Y) and in front (+Y)
+BASE_REAR_Y  = -80.0;   // base rear edge Y coordinate
+
+// ── Pogo pin housing (in back wall front face) ────────────────────────────────
+// High-current pogo pins: Ø5.5 mm body, 20 mm long (compressed), 4 mm spring travel
+// Rated 5 A each; 2× pins for +/- power
+POGO_D         =  5.5;    // pogo pin body OD
+POGO_BORE_D    =  5.7;    // bore diameter (0.2 mm clearance)
+POGO_L         = 20.0;    // pogo full length (uncompressed)
+POGO_TRAVEL    =  4.0;    // spring travel
+POGO_FLANGE_D  =  8.0;    // pogo flange / retention shoulder OD
+POGO_FLANGE_T  =  1.5;    // flange thickness
+POGO_SPACING   = 20.0;    // CL-to-CL spacing between + and - pins
+POGO_Z         = 35.0;    // pogo CL height above dock floor
+POGO_PROTRUDE  =  8.0;    // pogo tip protrusion beyond wall face (uncompressed)
+// Wiring channel behind pogo (runs down to base)
+WIRE_CH_W      =  8.0;
+WIRE_CH_H      = POGO_Z + 5;
+
+// ── LED bezel (4 status LEDs in back wall, above pogo pins) ───────────────────
+// LED order (left to right): Searching | Aligned | Charging | Full
+// Colours (suggested): Red | Yellow | Blue | Green
+LED_D          =  5.0;    // 5 mm through-hole LED
+LED_BORE_D     =  5.2;    // bore diameter
+LED_BEZEL_W    = 80.0;    // bezel plate width
+LED_BEZEL_H    = 18.0;    // bezel plate height
+LED_BEZEL_T    =  4.0;    // bezel plate thickness
+LED_SPACING    = 16.0;    // LED centre-to-centre
+LED_Z          = 65.0;    // LED centre height above floor
+LED_INSET_D    =  2.0;    // LED recess depth (LED body recessed for protection)
+
+// ── V-guide rails ─────────────────────────────────────────────────────────────
+// Robot receiver width (contact block): 30 mm.
+// Alignment tolerance: ±20 mm → entry gap = 30 + 2×20 = 70 mm.
+// Guide rail tapers from 70 mm entry (at Y = GUIDE_L) to 30 mm exit (at Y=0).
+// Each rail is a wedge-shaped wall.
+GUIDE_L     = 100.0;   // guide rail length (Y depth, from back wall)
+GUIDE_H     =  50.0;   // guide rail height (Z)
+GUIDE_T     =   8.0;   // guide rail wall thickness
+RECV_W      =  30.0;   // robot receiver contact block width
+ENTRY_GAP   =  70.0;   // guide entry gap (= RECV_W + 2×20 mm tolerance)
+EXIT_GAP    =  RECV_W + 2.0;   // guide exit gap (2 mm clearance on each side)
+// Derived: half-gap at entry = 35 mm, at exit = 16 mm; taper = 19 mm over 100 mm
+// Half-angle = atan(19/100) ≈ 10.8° — gentle enough for reliable self-alignment
+
+// ── ArUco marker mount ────────────────────────────────────────────────────────
+// Mounted at dock entry arch (forward of guide rails), tilted 15° back.
+// Robot camera acquires marker for coarse approach alignment.
+// ArUco marker ID 42 (DICT_4X4_250), 100×100 mm (printed/laminated on paper).
+ARUCO_MARKER_W  = 100.0;
+ARUCO_MARKER_H  = 100.0;
+ARUCO_FRAME_T   =   3.0;   // frame plate thickness
+ARUCO_FRAME_BDR =  10.0;   // frame border around marker
+ARUCO_SLOT_T    =   1.5;   // marker slip-in slot depth
+ARUCO_MAST_H    =  95.0;   // mast height above base (centres marker at camera height)
+ARUCO_MAST_W    =  10.0;
+ARUCO_TILT      =  15.0;   // backward tilt (degrees) — faces approaching robot
+ARUCO_Y         = GUIDE_L + 60;  // mast Y position (in front of guide entry)
+
+// ── PSU bracket ───────────────────────────────────────────────────────────────
+// Mean Well IRM-240-24 (24V 10A 240W): 210×108×56 mm body — Issue #505 upgrade
+// Bracket sits behind back wall, on base plate.
+PSU_W   = 220.0;   // bracket internal width (+5 mm clearance per side for 210 mm PSU)
+PSU_D   = 118.0;   // bracket internal depth (+5 mm clearance per side for 108 mm PSU)
+PSU_H   = 66.0;    // bracket internal height (+5 mm top clearance for 56 mm PSU + ventilation)
+PSU_T   =  4.0;    // bracket wall thickness (thicker for larger PSU mass)
+PSU_Y   = BASE_REAR_Y + PSU_D/2 + PSU_T + 10;   // PSU Y centre
+
+// ── Fasteners ─────────────────────────────────────────────────────────────────
+M3_D = 3.3;
+M4_D = 4.3;
+M5_D = 5.3;
+M8_D = 8.5;
+
+// ============================================================
+// RENDER DISPATCH
+// ============================================================
+RENDER = "assembly";
+
+if      (RENDER == "assembly")       assembly();
+else if (RENDER == "base_stl")       dock_base();
+else if (RENDER == "back_wall_stl")  back_wall();
+else if (RENDER == "guide_rail_stl") guide_rail("left");
+else if (RENDER == "aruco_mount_stl") aruco_mount();
+else if (RENDER == "psu_bracket_stl") psu_bracket();
+else if (RENDER == "led_bezel_stl")  led_bezel();
+
+// ============================================================
+// ASSEMBLY PREVIEW
+// ============================================================
+module assembly() {
+    // Base plate
+    color("SaddleBrown", 0.85) dock_base();
+
+    // Back wall
+    color("Sienna", 0.85)
+        translate([0, 0, BASE_T])
+            back_wall();
+
+    // Left guide rail
+    color("Peru", 0.85)
+        translate([0, 0, BASE_T])
+            guide_rail("left");
+
+    // Right guide rail (mirror in X)
+    color("Peru", 0.85)
+        translate([0, 0, BASE_T])
+            mirror([1, 0, 0])
+                guide_rail("left");
+
+    // ArUco mount
+    color("DimGray", 0.85)
+        translate([0, 0, BASE_T])
+            aruco_mount();
+
+    // PSU bracket
+    color("DarkSlateGray", 0.80)
+        translate([0, PSU_Y, BASE_T])
+            psu_bracket();
+
+    // LED bezel
+    color("LightGray", 0.90)
+        translate([0, -WALL_T/2, BASE_T + LED_Z])
+            led_bezel();
+
+    // Ghost robot receiver approaching from +Y
+    %color("SteelBlue", 0.25)
+        translate([0, GUIDE_L + 30, BASE_T + POGO_Z])
+            cube([RECV_W, 20, 8], center = true);
+
+    // Ghost pogo pins
+    for (px = [-POGO_SPACING/2, POGO_SPACING/2])
+        %color("Gold", 0.60)
+            translate([px, -POGO_PROTRUDE, BASE_T + POGO_Z])
+                rotate([90, 0, 0])
+                    cylinder(d = POGO_D, h = POGO_L);
+}
+
+// ============================================================
+// PART A — DOCK BASE PLATE
+// ============================================================
+module dock_base() {
+    difference() {
+        // ── Main base block (rounded rect) ──────────────────────────
+        linear_extrude(BASE_T)
+            minkowski() {
+                square([BASE_W - 2*BASE_R,
+                        BASE_D - 2*BASE_R], center = true);
+                circle(r = BASE_R);
+            }
+
+        // ── Ballast pockets (underside) ──────────────────────────────
+        // 4× pockets: 2 front, 2 rear
+        for (bx = [-1, 1])
+        for (by = [-1, 1])
+            translate([bx * (BASE_W/2 - BALLAST_INSET_X),
+                       by * (BASE_D/2 - BALLAST_INSET_Y),
+                       -e])
+                cube([BALLAST_W, BALLAST_D, BALLAST_T + e], center = true);
+
+        // ── Floor bolt holes (M8, 4 corners) ────────────────────────
+        for (bx = [-1, 1])
+        for (by = [-1, 1])
+            translate([bx * (BASE_W/2 - FLOOR_BOLT_INSET_X),
+                       by * (BASE_D/2 - FLOOR_BOLT_INSET_Y), -e])
+                cylinder(d = FLOOR_BOLT_D, h = BASE_T + 2*e);
+
+        // ── Back wall attachment slots (M4, top face) ─────────────────
+        for (bx = [-WALL_W/2 + 30, 0, WALL_W/2 - 30])
+            translate([bx, -BASE_D/4, BASE_T - 3])
+                cylinder(d = M4_D, h = 4 + e);
+
+        // ── Guide rail attachment holes (M4) ──────────────────────────
+        for (side = [-1, 1])
+        for (gy = [20, GUIDE_L - 20])
+            translate([side * (EXIT_GAP/2 + GUIDE_T/2), gy, BASE_T - 3])
+                cylinder(d = M4_D, h = 4 + e);
+
+        // ── Cable routing slot (from pogo wires to PSU, through base) ─
+        translate([0, -WALL_T - 5, -e])
+            cube([WIRE_CH_W, 15, BASE_T + 2*e], center = true);
+
+        // ── Anti-skid texture (front face chamfer) ───────────────────
+        // Chamfer front-bottom edge for easy robot approach
+        translate([0, BASE_D/2 + e, -e])
+            rotate([45, 0, 0])
+                cube([BASE_W + 2*e, 5, 5], center = true);
+    }
+}
+
+// ============================================================
+// PART B — BACK WALL (upright panel)
+// ============================================================
+module back_wall() {
+    difference() {
+        union() {
+            // ── Wall slab ────────────────────────────────────────────
+            translate([-WALL_W/2, -WALL_T, 0])
+                cube([WALL_W, WALL_T, WALL_H]);
+
+            // ── Pogo pin housing bosses (front face) ─────────────────
+            for (px = [-POGO_SPACING/2, POGO_SPACING/2])
+                translate([px, -WALL_T, POGO_Z])
+                    rotate([90, 0, 0])
+                        cylinder(d = POGO_FLANGE_D + 6,
+                                 h = POGO_PROTRUDE);
+
+            // ── Wiring channel reinforcement (inside wall face) ───────
+            translate([-WIRE_CH_W/2 - 2, -WALL_T, 0])
+                cube([WIRE_CH_W + 4, 4, WIRE_CH_H]);
+        }
+
+        // ── Pogo pin bores (through wall into housing boss) ───────────
+        for (px = [-POGO_SPACING/2, POGO_SPACING/2])
+            translate([px, POGO_PROTRUDE + e, POGO_Z])
+                rotate([90, 0, 0]) {
+                    // Main bore (full depth through wall + boss)
+                    cylinder(d = POGO_BORE_D,
+                             h = WALL_T + POGO_PROTRUDE + 2*e);
+                    // Flange shoulder counterbore (retains pogo from pulling out)
+                    translate([0, 0, WALL_T + POGO_PROTRUDE - POGO_FLANGE_T - 1])
+                        cylinder(d = POGO_FLANGE_D + 0.4,
+                                 h = POGO_FLANGE_T + 2);
+                }
+
+        // ── Wiring channel (vertical slot, inside face → base cable hole) ─
+        translate([-WIRE_CH_W/2, 0 + e, 0])
+            cube([WIRE_CH_W, WALL_T/2, WIRE_CH_H]);
+
+        // ── LED bezel recess (in front face, above pogo) ──────────────
+        translate([-LED_BEZEL_W/2, -LED_BEZEL_T, LED_Z - LED_BEZEL_H/2])
+            cube([LED_BEZEL_W, LED_BEZEL_T + e, LED_BEZEL_H]);
+
+        // ── M4 base attachment bores (3 through bottom of wall) ───────
+        for (bx = [-WALL_W/2 + 30, 0, WALL_W/2 - 30])
+            translate([bx, -WALL_T/2, -e])
+                cylinder(d = M4_D, h = 8 + e);
+
+        // ── Cable tie slots (in wall body, for neat wire routing) ─────
+        for (cz = [15, POGO_Z - 15])
+            translate([WIRE_CH_W/2 + 3, -WALL_T/2, cz])
+                cube([4, WALL_T + 2*e, 3], center = true);
+
+        // ── Lightening cutout (rear face pocket) ──────────────────────
+        translate([-WALL_W/2 + 40, 0, 20])
+            cube([WALL_W - 80, WALL_T/2 + e, WALL_H - 30]);
+    }
+}
+
+// ============================================================
+// PART C — V-GUIDE RAIL
+// ============================================================
+// Print 2×; mirror in X for right side.
+// Rail tapers from ENTRY_GAP/2 (at Y=GUIDE_L) to EXIT_GAP/2 (at Y=0).
+// Inner (guiding) face is angled; outer face is vertical.
+module guide_rail(side = "left") {
+    // Inner face X at back wall  = EXIT_GAP/2
+    // Inner face X at entry      = ENTRY_GAP/2
+    x_back  = EXIT_GAP/2;        // 16 mm
+    x_entry = ENTRY_GAP/2;       // 35 mm
+
+    difference() {
+        union() {
+            // ── Main wedge body ─────────────────────────────────────
+            // Hull between two rectangles: narrow at Y=0, wide at Y=GUIDE_L
+            hull() {
+                // Back end (at Y=0, flush with back wall)
+                translate([x_back, 0, 0])
+                    cube([GUIDE_T, e, GUIDE_H]);
+                // Entry end (at Y=GUIDE_L)
+                translate([x_entry, GUIDE_L, 0])
+                    cube([GUIDE_T, e, GUIDE_H]);
+            }
+
+            // ── Entry flare (chamfered lip at guide entry for bump-entry) ─
+            hull() {
+                translate([x_entry, GUIDE_L, 0])
+                    cube([GUIDE_T, e, GUIDE_H]);
+                translate([x_entry + 15, GUIDE_L + 20, 0])
+                    cube([GUIDE_T, e, GUIDE_H * 0.6]);
+            }
+        }
+
+        // ── M4 base attachment bores ─────────────────────────────────
+        for (gy = [20, GUIDE_L - 20])
+            translate([x_back + GUIDE_T/2, gy, -e])
+                cylinder(d = M4_D, h = 8 + e);
+
+        // ── Chamfer on inner top corner (smooth robot entry) ─────────
+        translate([x_back - e, -e, GUIDE_H - 5])
+            rotate([0, -45, 0])
+                cube([8, GUIDE_L + 30, 8]);
+    }
+}
+
+// ============================================================
+// PART D — ArUco MARKER MOUNT
+// ============================================================
+// Free-standing mast at dock entry. Mounts to base plate.
+// Marker face tilted 15° toward approaching robot.
+// Accepts 100×100 mm printed/laminated paper marker in slot.
+module aruco_mount() {
+    frame_w  = ARUCO_MARKER_W + 2*ARUCO_FRAME_BDR;
+    frame_h  = ARUCO_MARKER_H + 2*ARUCO_FRAME_BDR;
+    mast_y   = ARUCO_Y;
+
+    union() {
+        // ── Mast column ───────────────────────────────────────────────
+        translate([-ARUCO_MAST_W/2, mast_y - ARUCO_MAST_W/2, 0])
+            cube([ARUCO_MAST_W, ARUCO_MAST_W, ARUCO_MAST_H]);
+
+        // ── Marker frame (tilted back ARUCO_TILT°) ────────────────────
+        translate([0, mast_y, ARUCO_MAST_H])
+            rotate([-ARUCO_TILT, 0, 0]) {
+                difference() {
+                    // Frame plate
+                    translate([-frame_w/2, -ARUCO_FRAME_T, -frame_h/2])
+                        cube([frame_w, ARUCO_FRAME_T, frame_h]);
+
+                    // Marker window (cutout for marker visibility)
+                    translate([-ARUCO_MARKER_W/2, -ARUCO_FRAME_T - e,
+                               -ARUCO_MARKER_H/2])
+                        cube([ARUCO_MARKER_W,
+                              ARUCO_FRAME_T + 2*e,
+                              ARUCO_MARKER_H]);
+
+                    // Marker slip-in slot (insert from side)
+                    translate([-frame_w/2 - e,
+                               -ARUCO_SLOT_T - 0.3,
+                               -ARUCO_MARKER_H/2])
+                        cube([frame_w + 2*e,
+                              ARUCO_SLOT_T + 0.3,
+                              ARUCO_MARKER_H]);
+                }
+            }
+
+        // ── Mast base foot (M4 bolts to dock base) ────────────────────
+        difference() {
+            translate([-20, mast_y - 20, 0])
+                cube([40, 40, 5]);
+            for (fx = [-12, 12]) for (fy = [-12, 12])
+                translate([fx, mast_y + fy, -e])
+                    cylinder(d = M4_D, h = 6 + e);
+        }
+    }
+}
+
+// ============================================================
+// PART E — PSU BRACKET
+// ============================================================
+// Open-top retention bracket for PSU module.
+// PSU slides in from top; 2× M3 straps or cable ties retain it.
+// Bracket bolts to base plate via 4× M4 screws.
+module psu_bracket() {
+    difference() {
+        union() {
+            // ── Outer bracket box (open top) ─────────────────────────
+            _box_open_top(PSU_W + 2*PSU_T,
+                          PSU_D + 2*PSU_T,
+                          PSU_H + PSU_T);
+
+            // ── Base flange ──────────────────────────────────────────
+            translate([-(PSU_W/2 + PSU_T + 8),
+                       -(PSU_D/2 + PSU_T + 8), -PSU_T])
+                cube([PSU_W + 2*PSU_T + 16,
+                      PSU_D + 2*PSU_T + 16, PSU_T]);
+        }
+
+        // ── PSU cavity ───────────────────────────────────────────────
+        translate([0, 0, PSU_T])
+            cube([PSU_W, PSU_D, PSU_H + e], center = true);
+
+        // ── Ventilation slots (sides) ─────────────────────────────────
+        for (a = [0, 90, 180, 270])
+            rotate([0, 0, a])
+                translate([0, (PSU_D/2 + PSU_T)/2, PSU_H/2 + PSU_T])
+                    for (sz = [-PSU_H/4, 0, PSU_H/4])
+                        translate([0, 0, sz])
+                            cube([PSU_W * 0.5, PSU_T + 2*e, 5],
+                                 center = true);
+
+        // ── Cable exit slot (bottom) ──────────────────────────────────
+        translate([0, 0, -e])
+            cube([15, PSU_D + 2*PSU_T + 2*e, PSU_T + 2*e],
+                 center = true);
+
+        // ── Base flange M4 bolts ──────────────────────────────────────
+        for (fx = [-1, 1]) for (fy = [-1, 1])
+            translate([fx * (PSU_W/2 + PSU_T + 4),
+                       fy * (PSU_D/2 + PSU_T + 4),
+                       -PSU_T - e])
+                cylinder(d = M4_D, h = PSU_T + 2*e);
+
+        // ── Cable tie slots ───────────────────────────────────────────
+        for (sz = [PSU_H/3, 2*PSU_H/3])
+            translate([0, 0, PSU_T + sz])
+                cube([PSU_W + 2*PSU_T + 2*e, 4, 4], center = true);
+    }
+}
+
+module _box_open_top(w, d, h) {
+    difference() {
+        cube([w, d, h], center = true);
+        translate([0, 0, PSU_T + e])
+            cube([w - 2*PSU_T, d - 2*PSU_T, h], center = true);
+    }
+}
+
+// ============================================================
+// PART F — LED STATUS BEZEL
+// ============================================================
+// 4 × 5 mm LEDs in a row. Press-fits into recess in back wall.
+// LED labels (L→R): SEARCHING | ALIGNED | CHARGING | FULL
+// Suggested colours:     Red  |  Yellow  |   Blue   | Green
+module led_bezel() {
+    difference() {
+        // Bezel plate
+        cube([LED_BEZEL_W, LED_BEZEL_T, LED_BEZEL_H], center = true);
+
+        // 4× LED bores
+        for (i = [-1.5, -0.5, 0.5, 1.5])
+            translate([i * LED_SPACING, -LED_BEZEL_T - e, 0])
+                rotate([90, 0, 0]) {
+                    // LED body bore (recess, not through)
+                    cylinder(d = LED_BORE_D + 1,
+                             h = LED_INSET_D + e);
+                    // LED pin bore (through bezel)
+                    translate([0, 0, LED_INSET_D])
+                        cylinder(d = LED_BORE_D,
+                                 h = LED_BEZEL_T + 2*e);
+                }
+
+        // Label recesses between LEDs (for colour-dot stickers or printed inserts)
+        for (i = [-1.5, -0.5, 0.5, 1.5])
+            translate([i * LED_SPACING, LED_BEZEL_T/2, LED_BEZEL_H/2 - 3])
+                cube([LED_SPACING - 3, 1 + e, 5], center = true);
+
+        // M3 mounting holes (2× into back wall)
+        for (mx = [-LED_BEZEL_W/2 + 6, LED_BEZEL_W/2 - 6])
+            translate([mx, -LED_BEZEL_T - e, 0])
+                rotate([90, 0, 0])
+                    cylinder(d = M3_D, h = LED_BEZEL_T + 2*e);
+    }
+}

chassis/charging_dock_505_BOM.csv

@@ -0,0 +1,41 @@
+Item,Description,Specification,Quantity,Unit Cost,Total Cost,Source Notes
+E1,Power Supply,Mean Well IRM-240-24 / Hi-Link HLK-240M24 (24V 10A 240W),1,$50.00,$50.00,Digi-Key / Amazon
+E2,12 AWG Silicone Wire,Red + Black 600V rated 5m spool,1,$15.00,$15.00,McMaster-Carr / AliExpress
+E3,PG7 Cable Gland,M20 IP67 5-8mm cable,2,$3.00,$6.00,AliExpress / Heilind
+E4,Varistor (MOV),18-28V 1kA,1,$1.00,$1.00,Digi-Key
+E5,Fuse 25A,T25 Slow-blow 5x20mm,1,$0.50,$0.50,Digi-Key
+E6,Fuse Holder,5x20mm inline 20A rated,1,$2.00,$2.00,Amazon
+E7,Crimp Ring Terminals,M3 12 AWG tin-plated,8,$0.20,$1.60,Heilind / AliExpress
+E8,Strain Relief Sleeve,5mm ID silicone 1m,1,$5.00,$5.00,McMaster-Carr
+C1,Pogo Pin Assembly,"Spring-loaded Ø5.5mm 20mm 20A 4mm travel",2,$10.00,$20.00,Preci-Dip / Jst / AliExpress
+C2,Brass Contact Pad,Ø12x2mm H68 brass bare,2,$3.00,$6.00,OnlineMetals / Metals USA
+C3,Solder Lug M3,Copper ring tin-plated,4,$0.40,$1.60,Heilind / Amazon
+L1,5mm LED Red,2.0V 20mA diffuse,1,$0.30,$0.30,Digi-Key
+L2,5mm LED Yellow,2.1V 20mA diffuse,1,$0.30,$0.30,Digi-Key
+L3,5mm LED Blue,3.2V 20mA diffuse,1,$0.50,$0.50,Digi-Key
+L4,5mm LED Green,2.1V 20mA diffuse,1,$0.30,$0.30,Digi-Key
+R1-R4,Resistor 1kΩ 1/4W,Metal film 1% tolerance,4,$0.10,$0.40,Digi-Key
+J1,Pin Header 2.54mm,1x6 right-angle,1,$0.50,$0.50,Digi-Key
+S1,INA219 I2C Shunt Monitor,16-bit I2C 0x40 26V max (Optional),1,$5.00,$5.00,Adafruit / Digi-Key
+S2,SMD Resistor 0.1Ω,1206 1W (Optional current sense),1,$1.00,$1.00,Digi-Key
+M1,M20 Hex Nut,Steel DIN 934 ~86g,8,$0.80,$6.40,Grainger / Home Depot
+M2,M4x16 SHCS,Stainless A4 DIN 912,16,$0.30,$4.80,Grainger
+M3,M4x10 BHCS,Stainless A4 DIN 7380,8,$0.25,$2.00,Grainger
+M4,M4 Heat-Set Insert,Brass threaded,20,$0.15,$3.00,McMaster-Carr
+M5,M3x16 SHCS,Stainless,4,$0.20,$0.80,Grainger
+M6,M3 Hex Nut,DIN 934,4,$0.10,$0.40,Grainger
+M7,M8x40 BHCS,Zinc-plated floor anchor,4,$0.50,$2.00,Grainger
+M8,Rubber Foot,Ø20x5mm self-adhesive,4,$0.80,$3.20,Amazon
+A1,ArUco Marker Print,"100x100mm ID=42 DICT_4X4_250 glossy photo (qty 2)",2,$1.50,$3.00,Print locally / AliExpress
+A2,Lamination Pouch,A4 80µm,2,$0.40,$0.80,Amazon / Staples
+A3,Acrylic Cover Sheet,Clear 3mm 150x150mm,1,$3.00,$3.00,McMaster-Carr
+X1,Solder Wire,63/37 Sn/Pb lead-free 1m,1,$3.00,$3.00,Digi-Key
+X2,Flux Paste,No-clean 25mL,1,$4.00,$4.00,Digi-Key
+X3,Loctite 243,Thread-locker 10mL,1,$4.00,$4.00,Grainger
+X4,Epoxy Adhesive,Two-part 25mL,1,$6.00,$6.00,Home Depot
+P1,PETG Filament (3D Print),"Natural/White 1kg ±15% waste factor",2.5,$20.00,$50.00,Prusament / Overture
+,,,,,
+SUBTOTAL (Electrical + Hardware + Consumables),,,,,,$234.00,excludes 3D printing
+SUBTOTAL (With 3D filament @ $20/kg),,,,,,$284.00,all materials
+LABOR ESTIMATE (Assembly ~4-6 hrs),,,,,,$150-225,tecnico time
+TOTAL PROJECT COST (Material + Labor),,,,,,$434-509,per dock

chassis/charging_dock_receiver_505.scad

@@ -0,0 +1,332 @@
+// ============================================================
+// charging_dock_receiver_505.scad — Robot-Side Charging Receiver (24V)
+// Issue: #505  Agent: sl-mechanical  Date: 2026-03-06
+// ============================================================
+//
+// Robot-side contact plate that mates with the 24V charging dock pogo pins.
+// Forked from Issue #159 receiver (contact geometry unchanged; 12 AWG wire bore).
+// Each robot variant has a different mounting interface; the contact
+// geometry is identical across all variants (same pogo pin spacing).
+//
+// Variants:
+//   A — lab_receiver()    SaltyLab — mounts to underside of stem base ring
+//   B — rover_receiver()  SaltyRover — mounts to chassis belly (M4 deck holes)
+//   C — tank_receiver()   SaltyTank — mounts to skid plate / hull floor
+//
+// Contact geometry (common across variants):
+//   2× brass contact pads, Ø12 mm × 2 mm (press-fit into PETG housing)
+//   Pad spacing: 20 mm CL-to-CL (matches dock POGO_SPACING exactly)
+//   Contact face Z height matches dock pogo pin Z when robot is level
+//   Polarity: marked + on top pin (conventional: positive = right when
+//   facing dock; negative = left) — must match dock wiring.
+//
+// Approach guide nose:
+//   A chamfered V-nose on the forward face guides the receiver block
+//   into the dock's V-funnel.  Taper half-angle ≈ 14° matches guide rails.
+//   Nose width = RECV_W = 30 mm (matches dock EXIT_GAP - 2 mm clearance).
+//
+// Coordinate convention:
+//   Z = 0 at receiver mounting face (against robot chassis/deck underside).
+//   +Z points downward (toward dock floor).
+//   Contact pads face +Y (toward dock back wall when docked).
+//   Receiver centred on X = 0 (robot centreline).
+//
+// RENDER options:
+//   "assembly"         all 3 receivers side by side
+//   "lab_stl"          SaltyLab receiver (print 1×)
+//   "rover_stl"        SaltyRover receiver (print 1×)
+//   "tank_stl"         SaltyTank receiver (print 1×)
+//   "contact_pad_2d"   DXF — Ø12 mm brass pad profile (order from metal shop)
+//
+// Export (Issue #505 24V variant):
+//   openscad charging_dock_receiver_505.scad -D 'RENDER="lab_stl"'   -o receiver_505_lab.stl
+//   openscad charging_dock_receiver_505.scad -D 'RENDER="rover_stl"' -o receiver_505_rover.stl
+//   openscad charging_dock_receiver_505.scad -D 'RENDER="tank_stl"'  -o receiver_505_tank.stl
+//   openscad charging_dock_receiver_505.scad -D 'RENDER="contact_pad_2d"' -o contact_pad_505.dxf
+// ============================================================
+
+$fn = 64;
+e   = 0.01;
+
+// ── Contact geometry (must match charging_dock.scad) ─────────────────────────
+POGO_SPACING   = 20.0;   // CL-to-CL (dock POGO_SPACING)
+PAD_D          = 12.0;   // contact pad OD (brass disc)
+PAD_T          =  2.0;   // contact pad thickness
+PAD_RECESS     =  1.8;   // pad pressed into housing (0.2 mm proud for contact)
+PAD_PROUD      =  0.2;   // pad face protrudes from housing face
+
+// ── Common receiver body geometry ────────────────────────────────────────────
+RECV_W         = 30.0;   // receiver body width (X) — matches dock EXIT_GAP inner
+RECV_D         = 25.0;   // receiver body depth (Y, docking direction)
+RECV_H         = 12.0;   // receiver body height (Z, from mount face down)
+RECV_R         =  3.0;   // corner radius
+// V-nose geometry (front Y face — faces dock back wall)
+NOSE_CHAMFER   = 10.0;   // chamfer depth on X corners of front face
+
+// Polarity indicator slot (on top/mount face: + on right, - on left)
+POL_SLOT_W     =  4.0;
+POL_SLOT_D     =  8.0;
+POL_SLOT_H     =  1.0;
+
+// Fasteners
+M2_D  = 2.4;
+M3_D  = 3.3;
+M4_D  = 4.3;
+
+// ── Mounting patterns ─────────────────────────────────────────────────────────
+// SaltyLab stem base ring (Ø25 mm stem, 4× M3 in ring at Ø40 mm BC)
+LAB_BC_D       = 40.0;
+LAB_BOLT_D     = M3_D;
+LAB_COLLAR_H   = 15.0;   // collar height above receiver body
+
+// SaltyRover deck (M4 grid pattern, 30.5×30.5 mm matching FC pattern on deck)
+// Receiver uses 4× M4 holes at ±20 mm from centre (clear of deck electronics)
+ROVER_BOLT_SPC = 40.0;
+
+// SaltyTank skid plate (M4 holes matching skid plate bolt pattern)
+// Uses 4× M4 at ±20 mm X, ±10 mm Y (inset from skid plate M4 positions)
+TANK_BOLT_SPC_X = 40.0;
+TANK_BOLT_SPC_Y = 20.0;
+TANK_NOSE_L     = 20.0;   // extended nose for tank (wider hull)
+
+// ============================================================
+// RENDER DISPATCH
+// ============================================================
+RENDER = "assembly";
+
+if      (RENDER == "assembly")       assembly();
+else if (RENDER == "lab_stl")        lab_receiver();
+else if (RENDER == "rover_stl")      rover_receiver();
+else if (RENDER == "tank_stl")       tank_receiver();
+else if (RENDER == "contact_pad_2d") {
+    projection(cut = true) translate([0, 0, -0.5])
+        linear_extrude(1) circle(d = PAD_D);
+}
+
+// ============================================================
+// ASSEMBLY PREVIEW
+// ============================================================
+module assembly() {
+    // SaltyLab receiver
+    color("RoyalBlue", 0.85)
+        translate([-80, 0, 0])
+            lab_receiver();
+
+    // SaltyRover receiver
+    color("OliveDrab", 0.85)
+        translate([0, 0, 0])
+            rover_receiver();
+
+    // SaltyTank receiver
+    color("SaddleBrown", 0.85)
+        translate([80, 0, 0])
+            tank_receiver();
+}
+
+// ============================================================
+// COMMON RECEIVER BODY
+// ============================================================
+// Internal helper: the shared contact housing + V-nose.
+// Orientation: mount face = +Z top; contact face = +Y front.
+// All variant-specific modules call this, then add their mount interface.
+module _receiver_body() {
+    difference() {
+        union() {
+            // ── Main housing block (rounded) ─────────────────────────
+            linear_extrude(RECV_H)
+                _recv_profile_2d();
+
+            // ── V-nose chamfer reinforcement ribs ─────────────────────
+            // Two diagonal ribs at 45° reinforce the chamfered corners
+            for (sx = [-1, 1])
+                hull() {
+                    translate([sx*(RECV_W/2 - NOSE_CHAMFER),
+                               RECV_D/2, 0])
+                        cylinder(d = 3, h = RECV_H * 0.6);
+                    translate([sx*(RECV_W/2), RECV_D/2 - NOSE_CHAMFER, 0])
+                        cylinder(d = 3, h = RECV_H * 0.6);
+                }
+        }
+
+        // ── Contact pad bores (2× Ø12 mm, press-fit) ─────────────────
+        // Pads face +Y; bores from Y face into housing
+        for (px = [-POGO_SPACING/2, POGO_SPACING/2])
+            translate([px, RECV_D/2 + e, RECV_H/2])
+                rotate([90, 0, 0]) {
+                    // Pad press-fit bore
+                    cylinder(d = PAD_D + 0.1,
+                             h = PAD_RECESS + e);
+                    // Wire bore (behind pad, to mount face)
+                    translate([0, 0, PAD_RECESS])
+                        cylinder(d = 3.0,
+                                 h = RECV_D + 2*e);
+                }
+
+        // ── Polarity indicator slots on top face ──────────────────────
+        // "+" slot: right pad (+X side)
+        translate([POGO_SPACING/2, 0, -e])
+            cube([POL_SLOT_W, POL_SLOT_D, POL_SLOT_H + e], center = true);
+        // "-" indent: left pad (no slot = negative)
+
+        // ── Wire routing channel (on mount face / underside) ──────────
+        // Trough connecting both pad bores for neat wire run
+        translate([0, RECV_D/2 - POGO_SPACING/2, RECV_H - 3])
+            cube([POGO_SPACING + 6, POGO_SPACING, 4], center = true);
+    }
+}
+
+// ── 2D profile of receiver body with chamfered V-nose ────────────────────────
+module _recv_profile_2d() {
+    hull() {
+        // Rear corners (full width)
+        for (sx = [-1, 1])
+            translate([sx*(RECV_W/2 - RECV_R), -RECV_D/2 + RECV_R])
+                circle(r = RECV_R);
+        // Front corners (chamfered — narrowed by NOSE_CHAMFER)
+        for (sx = [-1, 1])
+            translate([sx*(RECV_W/2 - NOSE_CHAMFER - RECV_R),
+                       RECV_D/2 - RECV_R])
+                circle(r = RECV_R);
+    }
+}
+
+// ============================================================
+// PART A — SALTYLAB RECEIVER
+// ============================================================
+// Mounts to the underside of the SaltyLab chassis stem base ring.
+// Split collar grips Ø25 mm stem; receiver body hangs below collar.
+// Z height set so contact pads align with dock pogo pins when robot
+// rests on flat surface (robot wheel-to-contact-pad height calibrated).
+//
+// Receiver height above floor: tune LAB_CONTACT_Z in firmware (UWB/ArUco
+// approach). Mechanically: receiver sits ~35 mm above ground (stem base
+// height), matching dock POGO_Z = 35 mm.
+module lab_receiver() {
+    collar_od = 46.0;   // matches sensor_rail.scad STEM_COL_OD
+    collar_h  = LAB_COLLAR_H;
+
+    union() {
+        // ── Common receiver body ────────────────────────────────────
+        _receiver_body();
+
+        // ── Stem collar (split, 2 halves joined with M4 bolts) ───────
+        // Only the front half printed here; rear half is mirror.
+        translate([0, -RECV_D/2, RECV_H])
+            difference() {
+                // Half-collar cylinder
+                rotate_extrude(angle = 180)
+                    translate([collar_od/2 - 8, 0, 0])
+                        square([8, collar_h]);
+
+                // Stem bore clearance
+                translate([0, 0, -e])
+                    cylinder(d = 25.5, h = collar_h + 2*e);
+
+                // 2× M4 clamping bolt bores (through collar flanges)
+                for (cx = [-collar_od/2 + 4, collar_od/2 - 4])
+                    translate([cx, 0, collar_h/2])
+                        rotate([90, 0, 0])
+                            cylinder(d = M4_D,
+                                     h = collar_od + 2*e,
+                                     center = true);
+            }
+
+        // ── M3 receiver-to-collar bolts ───────────────────────────────
+        // 4× M3 holes connecting collar flange to receiver body top
+        // (These are mounting holes for assembly; not holes in the part)
+    }
+}
+
+// ============================================================
+// PART B — SALTYOVER RECEIVER
+// ============================================================
+// Mounts to the underside of the SaltyRover deck plate.
+// 4× M4 bolts into deck underside (blind holes tapped in deck).
+// Receiver sits flush with deck belly; contact pads protrude 5 mm below.
+// Dock pogo Z = 35 mm must equal ground-to-deck-belly height for rover
+// (approximately 60 mm chassis clearance — shim with spacer if needed).
+module rover_receiver() {
+    mount_h = 5.0;   // mounting flange thickness
+
+    union() {
+        // ── Common receiver body ────────────────────────────────────
+        _receiver_body();
+
+        // ── Mounting flange (attaches to deck belly) ─────────────────
+        difference() {
+            translate([-(ROVER_BOLT_SPC/2 + 12),
+                       -RECV_D/2 - 10,
+                       RECV_H])
+                cube([ROVER_BOLT_SPC + 24,
+                      RECV_D + 20,
+                      mount_h]);
+
+            // 4× M4 bolt holes
+            for (fx = [-1, 1]) for (fy = [-1, 1])
+                translate([fx*ROVER_BOLT_SPC/2,
+                           fy*(RECV_D/2 + 5),
+                           RECV_H - e])
+                    cylinder(d = M4_D,
+                             h = mount_h + 2*e);
+
+            // Weight-reduction pockets
+            for (sx = [-1, 1])
+                translate([sx*(ROVER_BOLT_SPC/4 + 6),
+                           0, RECV_H + 1])
+                    cube([ROVER_BOLT_SPC/2 - 4, RECV_D - 4, mount_h],
+                         center = true);
+        }
+    }
+}
+
+// ============================================================
+// PART C — SALTYTANK RECEIVER
+// ============================================================
+// Mounts to SaltyTank hull floor or replaces a section of skid plate.
+// Extended front nose (TANK_NOSE_L) for tank's wider hull approach.
+// Contact pads exposed through skid plate via a 30×16 mm slot.
+// Ground clearance: tank chassis = 90 mm; dock POGO_Z = 35 mm.
+// Use ramp shim (see BOM) under dock base to elevate pogo pins to 90 mm
+// OR set POGO_Z = 90 in dock for a tank-specific dock configuration.
+// ⚠ Cross-variant dock: set POGO_Z per robot if heights differ.
+//   Compromise: POGO_Z = 60 mm with 25 mm ramp for tank, 25 mm spacer for lab.
+module tank_receiver() {
+    mount_h = 4.0;
+    nose_l  = RECV_D/2 + TANK_NOSE_L;
+
+    union() {
+        // ── Common receiver body ────────────────────────────────────
+        _receiver_body();
+
+        // ── Extended nose for tank approach ──────────────────────────
+        // Additional chamfered wedge ahead of standard receiver body
+        hull() {
+            // Receiver front face corners
+            for (sx = [-1, 1])
+                translate([sx*(RECV_W/2 - NOSE_CHAMFER), RECV_D/2, 0])
+                    cylinder(d = 2*RECV_R, h = RECV_H * 0.5);
+            // Extended nose tip (narrowed to 20 mm)
+            for (sx = [-1, 1])
+                translate([sx*10, RECV_D/2 + TANK_NOSE_L, 0])
+                    cylinder(d = 2*RECV_R, h = RECV_H * 0.4);
+        }
+
+        // ── Mounting flange (bolts to tank skid plate) ────────────────
+        difference() {
+            translate([-(TANK_BOLT_SPC_X/2 + 10),
+                       -RECV_D/2 - 8,
+                       RECV_H])
+                cube([TANK_BOLT_SPC_X + 20,
+                      RECV_D + 16,
+                      mount_h]);
+
+            // 4× M4 bolt holes
+            for (fx = [-1, 1]) for (fy = [-1, 1])
+                translate([fx*TANK_BOLT_SPC_X/2,
+                           fy*TANK_BOLT_SPC_Y/2,
+                           RECV_H - e])
+                    cylinder(d = M4_D,
+                             h = mount_h + 2*e);
+        }
+    }
+}

chassis/chassis_frame.scad

@@ -8,9 +8,9 @@
 // Requirements:
 //   - 600mm wheelbase
 //   - 2x hoverboard hub motors (170mm OD)
-//   - STM32 MAMBA F722S FC mount (30.5x30.5mm pattern)
+//   - ESP32-S3 ESP32-S3 BALANCE FC mount (30.5x30.5mm pattern)
 //   - Battery tray (24V 4Ah — ~180x70x50mm pack)
-//   - Jetson Nano B01 mount plate (100x80mm, M3 holes)
+//   - Jetson Orin Nano Super B01 mount plate (100x80mm, M3 holes)
 //   - Front/rear bumper brackets
 // =============================================================================
 
@@ -37,7 +37,7 @@ MOTOR_FORK_H       = 80;    // mm, total height of motor fork bracket
 MOTOR_FORK_T       = 8;     // mm, fork plate thickness
 AXLE_HEIGHT        = 310;   // mm, axle CL above ground (motor radius + clearance)
 
-// ── FC mount (MAMBA F722S — 30.5 × 30.5 mm M3 pattern) ──────────────────────
+// ── FC mount (ESP32-S3 BALANCE — 30.5 × 30.5 mm M3 pattern) ──────────────────────
 FC_MOUNT_SPACING   = 30.5;  // mm, hole pattern pitch
 FC_MOUNT_HOLE_D    = 3.2;   // mm, M3 clearance
 FC_STANDOFF_H      = 6;     // mm, standoff height
@@ -52,7 +52,7 @@ BATT_FLOOR         = 4;     // mm, tray floor thickness
 BATT_STRAP_W       = 20;    // mm, Velcro strap slot width
 BATT_STRAP_T       = 2;     // mm, strap slot depth
 
-// ── Jetson Nano B01 mount plate ──────────────────────────────────────────────
+// ── Jetson Orin Nano Super B01 mount plate ──────────────────────────────────────────────
 // B01 carrier board hole pattern: 58 x 58 mm M3 (inner) + corner pass-throughs
 JETSON_HOLE_PITCH  = 58;    // mm, M3 mounting hole pattern
 JETSON_HOLE_D      = 3.2;   // mm
@@ -210,7 +210,7 @@ module battery_tray() {
 
 // ─── FC mount holes helper ────────────────────────────────────────────────────
 module fc_mount_holes(z_offset=0, depth=10) {
-    // MAMBA F722S: 30.5×30.5 mm M3 pattern, centred at origin
+    // ESP32-S3 BALANCE: 30.5×30.5 mm M3 pattern, centred at origin
     for (x = [-FC_MOUNT_SPACING/2, FC_MOUNT_SPACING/2])
     for (y = [-FC_MOUNT_SPACING/2, FC_MOUNT_SPACING/2])
         translate([x, y, z_offset])
@@ -247,7 +247,7 @@ module fc_mount_plate() {
     }
 }
 
-// ─── Jetson Nano B01 mount plate ─────────────────────────────────────────────
+// ─── Jetson Orin Nano Super B01 mount plate ─────────────────────────────────────────────
 // Positioned rear of deck, elevated on standoffs
 module jetson_mount_plate() {
     jet_x =  60;   // offset toward rear

chassis/gimbal_camera_mount.scad

@@ -0,0 +1,599 @@
+// ============================================================
+// gimbal_camera_mount.scad — Pan/Tilt Gimbal Mount for RealSense D435i
+// Issue: #552  Agent: sl-mechanical  Date: 2026-03-14
+// ============================================================
+//
+// Parametric gimbal bracket system mounting an Intel RealSense D435i
+// (or similar box camera) on a 2-axis pan/tilt gimbal driven by
+// ST3215 serial bus servos (25T spline, Feetech/Waveshare).
+//
+// Architecture:
+//   Pan axis  — base T-nut clamps to 2020 rail; pan servo rotates yoke
+//   Tilt axis — tilt servo horn plate bolts to ST3215 horn; camera cradle
+//               rocks on tilt axis
+//   Camera    — D435i captured via 1/4-20 UNC hex nut in cradle floor
+//   Damping   — PETG flexure ribs on camera contact faces (or TPU pads)
+//   Wiring    — USB-C cable routed through channel in cradle arm
+//
+// Part catalogue:
+//   Part 1 — tnut_rail_base()       2020 rail T-nut base + pan servo seat
+//   Part 2 — pan_yoke()             U-yoke connecting pan servo to tilt axis
+//   Part 3 — tilt_horn_plate()      Plate bolting to ST3215 tilt servo horn
+//   Part 4 — camera_cradle()        D435i cradle with 1/4-20 captured nut
+//   Part 5 — vibe_pad()             PETG flexure vibration-damping pad (×2)
+//   Part 6 — assembly_preview()     Full assembly preview
+//
+// Hardware BOM (per gimbal):
+//   2× ST3215 serial bus servo (pan + tilt)
+//   2× servo horn (25T spline, ≥Ø36 mm, 4× M3 bolt holes on Ø24 mm BC)
+//   2× M3 × 8 mm SHCS          horn-to-plate bolts (×4 each horn = 8 total)
+//   1× M3 × 16 mm SHCS + nut   T-nut rail clamp thumbscrew
+//   1× 1/4-20 UNC × 8 mm SHCS  camera retention bolt (or existing tripod screw)
+//   1× 1/4-20 UNC hex nut       captured in cradle floor
+//   4× M3 × 12 mm SHCS          yoke-to-tilt-plate pivot axle bolts
+//   2× M3 × 25 mm SHCS          pan yoke attachment to servo body
+//   (optional) 2× vibe_pad printed in TPU 95A
+//
+// ST3215 servo interface (caliper-verified Feetech ST3215):
+//   Body footprint : 40.0 × 20.0 mm (W × D), 36.5 mm tall
+//   Shaft centre H : 28.5 mm from mounting face
+//   Shaft spline   : 25T, centre Ø5.8 mm, D-cut
+//   Mount holes    : 4× M3 on 32 × 10 mm rectangular pattern (18 mm offset)
+//   Horn bolt circle: Ø24 mm, 4× M3
+//   Horn OD        : ~36 mm
+//
+// D435i camera interface (caliper-verified):
+//   Body           : 90 × 25 × 25 mm (W × D × H)
+//   Tripod thread  : 1/4-20 UNC, centred bottom face, 9 mm from front
+//   USB-C connector: right rear, 8 × 5 mm opening, 4 mm from edge
+//
+// Parametric camera size (override to adapt to other cameras):
+//   CAM_W, CAM_D, CAM_H  — body envelope
+//   CAM_MOUNT_X           — tripod hole X offset from camera centre
+//   CAM_MOUNT_Y           — tripod hole Y offset from front face
+//
+// Coordinate convention:
+//   Camera looks in +Y direction (forward)
+//   Pan axis is Z (vertical); tilt axis is X (lateral)
+//   Rail runs along Z; T-nut base at Z=0
+//   All parts at assembly origin; translate for assembly_preview
+//
+// RENDER options:
+//   "assembly"            full assembly preview (default)
+//   "tnut_rail_base_stl"  Part 1
+//   "pan_yoke_stl"        Part 2
+//   "tilt_horn_plate_stl" Part 3
+//   "camera_cradle_stl"   Part 4
+//   "vibe_pad_stl"        Part 5
+//
+// Export commands:
+//   openscad gimbal_camera_mount.scad -D 'RENDER="tnut_rail_base_stl"'  -o gcm_tnut_base.stl
+//   openscad gimbal_camera_mount.scad -D 'RENDER="pan_yoke_stl"'        -o gcm_pan_yoke.stl
+//   openscad gimbal_camera_mount.scad -D 'RENDER="tilt_horn_plate_stl"' -o gcm_tilt_horn_plate.stl
+//   openscad gimbal_camera_mount.scad -D 'RENDER="camera_cradle_stl"'   -o gcm_camera_cradle.stl
+//   openscad gimbal_camera_mount.scad -D 'RENDER="vibe_pad_stl"'        -o gcm_vibe_pad.stl
+// ============================================================
+
+$fn = 64;
+e   = 0.01;   // epsilon for boolean clearance
+
+// ── Parametric camera envelope ────────────────────────────────────────────────
+// Override these for cameras other than D435i
+CAM_W          = 90.0;   // camera body width (X)
+CAM_D          = 25.0;   // camera body depth (Y)
+CAM_H          = 25.0;   // camera body height (Z)
+CAM_MOUNT_X    =  0.0;   // tripod hole X offset from camera body centre
+CAM_MOUNT_Y    =  9.0;   // tripod hole from front face (Y)  [D435i: 9 mm]
+CAM_USBC_X     = CAM_W/2 - 4;   // USB-C connector X (right side)
+CAM_USBC_Z     = CAM_H/2;       // USB-C connector Z (mid-height rear)
+CAM_USBC_W     =  9.0;   // USB-C opening width (X)
+CAM_USBC_H     =  5.0;   // USB-C opening height (Z)
+
+// ── Rail geometry (matches sensor_rail.scad / sensor_rail_brackets.scad) ─────
+RAIL_W         = 20.0;
+SLOT_OPEN      =  6.0;
+SLOT_INNER_W   = 10.2;
+SLOT_INNER_H   =  5.8;
+SLOT_NECK_H    =  3.2;
+
+// ── T-nut geometry (matches sensor_rail_brackets.scad) ───────────────────────
+TNUT_W         =  9.8;
+TNUT_H         =  5.5;
+TNUT_L         = 12.0;
+TNUT_M3_NUT_AF =  5.5;
+TNUT_M3_NUT_H  =  2.5;
+TNUT_BOLT_D    =  3.3;   // M3 clearance
+
+// ── T-nut base plate geometry ─────────────────────────────────────────────────
+BASE_W         = 44.0;   // wide enough for pan servo body (40 mm)
+BASE_H         = 40.0;   // height along rail (Z)
+BASE_T         = SLOT_NECK_H + 2.0;   // plate depth (Y), rail-face side
+
+// ── ST3215 servo geometry ─────────────────────────────────────────────────────
+SERVO_W        = 40.0;   // servo body width (X)
+SERVO_D        = 20.0;   // servo body depth (Y)
+SERVO_H        = 36.5;   // servo body height (Z)
+SERVO_SHAFT_Z  = 28.5;   // shaft centre height from mounting face
+SERVO_HOLE_X   = 16.0;   // mount hole half-span X (32 mm span)
+SERVO_HOLE_Y   =  5.0;   // mount hole half-span Y (10 mm span)
+SERVO_M3_D     =  3.3;   // M3 clearance
+
+// ── Servo horn geometry ───────────────────────────────────────────────────────
+HORN_OD        = 36.0;   // horn outer diameter
+HORN_SPLINE_D  =  5.9;   // 25T spline bore clearance (5.8 + 0.1)
+HORN_BC_D      = 24.0;   // bolt circle diameter (4× M3)
+HORN_BOLT_D    =  3.3;   // M3 clearance through horn plate
+HORN_PLATE_T   =  5.0;   // tilt horn plate thickness
+
+// ── Yoke geometry ─────────────────────────────────────────────────────────────
+YOKE_WALL_T    =  5.0;   // yoke arm wall thickness
+YOKE_ARM_H     = 50.0;   // yoke arm height (Z) — clears servo body + camera
+YOKE_INNER_W   = CAM_W + 8.0;  // yoke inner span (camera + pad clearance)
+YOKE_BASE_T    =  8.0;   // yoke base plate thickness
+
+// ── Tilt pivot ────────────────────────────────────────────────────────────────
+PIVOT_D        =  4.3;   // M4 pivot axle bore
+PIVOT_BOSS_D   = 10.0;   // boss OD around pivot bore
+PIVOT_BOSS_L   =  6.0;   // boss protrusion from yoke wall
+
+// ── Camera cradle geometry ────────────────────────────────────────────────────
+CRADLE_WALL_T  =  4.0;   // cradle side wall thickness
+CRADLE_FLOOR_T =  5.0;   // cradle floor thickness (holds 1/4-20 nut)
+CRADLE_LIP_T   =  3.0;   // front retaining lip thickness
+CRADLE_LIP_H   =  8.0;   // front lip height
+CABLE_CH_W     = 12.0;   // USB-C cable channel width
+CABLE_CH_H     =  8.0;   // USB-C cable channel height
+
+// ── 1/4-20 UNC tripod thread ──────────────────────────────────────────────────
+QTR20_D        =  6.6;   // 1/4-20 clearance bore
+QTR20_NUT_AF   = 11.1;   // 1/4-20 hex nut across-flats (standard)
+QTR20_NUT_H    =  5.5;   // 1/4-20 hex nut height
+
+// ── Vibration-damping pad geometry ────────────────────────────────────────────
+PAD_W          = CAM_W - 2*CRADLE_WALL_T - 2;
+PAD_H          = CAM_H + 4;
+PAD_T          =  2.5;   // pad body thickness
+RIB_H          =  1.5;   // flexure rib height
+RIB_W          =  1.2;   // rib width
+RIB_PITCH      =  5.0;   // rib pitch
+
+// ── Fastener sizes ────────────────────────────────────────────────────────────
+M3_D = 3.3;
+M4_D = 4.3;
+M3_NUT_AF = 5.5;
+M3_NUT_H  = 2.4;
+
+// ============================================================
+// RENDER DISPATCH
+// ============================================================
+RENDER = "assembly";
+
+if      (RENDER == "assembly")            assembly_preview();
+else if (RENDER == "tnut_rail_base_stl")  tnut_rail_base();
+else if (RENDER == "pan_yoke_stl")        pan_yoke();
+else if (RENDER == "tilt_horn_plate_stl") tilt_horn_plate();
+else if (RENDER == "camera_cradle_stl")   camera_cradle();
+else if (RENDER == "vibe_pad_stl")        vibe_pad();
+
+// ============================================================
+// ASSEMBLY PREVIEW
+// ============================================================
+module assembly_preview() {
+    asm_rail_z = 0;
+    // Rail section ghost (200 mm)
+    %color("Silver", 0.25)
+        translate([-RAIL_W/2, -RAIL_W/2, asm_rail_z])
+            cube([RAIL_W, RAIL_W, 200]);
+
+    // T-nut rail base
+    color("OliveDrab", 0.85)
+        translate([0, 0, asm_rail_z + 80])
+            tnut_rail_base();
+
+    // Pan servo ghost (sitting in base seat)
+    %color("DimGray", 0.4)
+        translate([-SERVO_W/2, BASE_T, asm_rail_z + 80 + (BASE_H - SERVO_H)/2])
+            cube([SERVO_W, SERVO_D, SERVO_H]);
+
+    // Pan yoke rising from servo shaft
+    color("SteelBlue", 0.85)
+        translate([0, BASE_T + SERVO_D, asm_rail_z + 80 + BASE_H/2])
+            pan_yoke();
+
+    // Tilt horn plate (tilt axis — left yoke wall)
+    color("DarkOrange", 0.85)
+        translate([-YOKE_INNER_W/2 - YOKE_WALL_T - HORN_PLATE_T,
+                   BASE_T + SERVO_D + YOKE_BASE_T,
+                   asm_rail_z + 80 + BASE_H/2 + YOKE_ARM_H/2])
+            rotate([0, 90, 0])
+                tilt_horn_plate();
+
+    // Camera cradle (centred in yoke)
+    color("DarkSlateGray", 0.85)
+        translate([0, BASE_T + SERVO_D + YOKE_BASE_T + CRADLE_FLOOR_T,
+                   asm_rail_z + 80 + BASE_H/2 + YOKE_ARM_H/2 - CAM_H/2])
+            camera_cradle();
+
+    // D435i ghost
+    %color("Black", 0.4)
+        translate([-CAM_W/2,
+                   BASE_T + SERVO_D + YOKE_BASE_T + CRADLE_FLOOR_T + PAD_T,
+                   asm_rail_z + 80 + Base_H_mid() - CAM_H/2])
+            cube([CAM_W, CAM_D, CAM_H]);
+
+    // Vibe pads (front + rear camera face)
+    color("DimGray", 0.80) {
+        translate([-CAM_W/2 + CRADLE_WALL_T + 1,
+                   Base_T + SERVO_D + YOKE_BASE_T + CRADLE_FLOOR_T,
+                   asm_rail_z + 80 + Base_H_mid() - PAD_H/2])
+            rotate([90, 0, 0])
+                vibe_pad();
+    }
+}
+
+// helper (avoids recomputing same expression)
+function Base_T() = BASE_T;
+function Base_H_mid() = BASE_H/2 + YOKE_ARM_H/2;
+
+// ============================================================
+// PART 1 — T-NUT RAIL BASE  (pan servo seat + rail clamp)
+// ============================================================
+// Mounts to 2020 rail via standard T-nut tongue.
+// Front face (+Y side) provides flat seat for pan ST3215 servo body.
+// Servo body recessed 1 mm into seat for positive lateral registration.
+// Pan servo shaft axis = Z (vertical) → pan rotation about Z.
+//
+// Print: PETG, 5 perims, 50 % gyroid. Orient face-plate down (flat).
+module tnut_rail_base() {
+    difference() {
+        union() {
+            // ── Face plate (against rail outer face, -Y side) ────────────
+            translate([-BASE_W/2, -BASE_T, 0])
+                cube([BASE_W, BASE_T, BASE_H]);
+
+            // ── T-nut neck (enters rail slot, +Y side of face plate) ─────
+            translate([-TNUT_W/2, 0, (BASE_H - TNUT_L)/2])
+                cube([TNUT_W, SLOT_NECK_H + e, TNUT_L]);
+
+            // ── T-nut inner body (wider, locks inside T-groove) ──────────
+            translate([-TNUT_W/2, SLOT_NECK_H - e, (BASE_H - TNUT_L)/2])
+                cube([TNUT_W, TNUT_H - SLOT_NECK_H + e, TNUT_L]);
+
+            // ── Pan servo seat boss (front face, +Y side) ────────────────
+            // Proud pad that servo body sits on; 1 mm registration recess
+            translate([-BASE_W/2, -BASE_T, 0])
+                cube([BASE_W, BASE_T + 6, BASE_H]);
+        }
+
+        // ── Rail clamp bolt bore (M3 through face plate) ─────────────────
+        translate([0, -BASE_T - e, BASE_H/2])
+            rotate([-90, 0, 0])
+                cylinder(d = TNUT_BOLT_D, h = BASE_T + TNUT_H + 2*e);
+
+        // ── M3 hex nut pocket (inside T-nut body) ────────────────────────
+        translate([0, SLOT_NECK_H + 0.3, BASE_H/2])
+            rotate([-90, 0, 0])
+                cylinder(d = TNUT_M3_NUT_AF / cos(30),
+                         h = TNUT_M3_NUT_H + 0.3, $fn = 6);
+
+        // ── Servo body recess (1 mm registration pocket in seat face) ────
+        translate([-SERVO_W/2 - 0.3, -BASE_T + 6 - 1.0,
+                   (BASE_H - SERVO_H)/2 - 0.3])
+            cube([SERVO_W + 0.6, 1.2, SERVO_H + 0.6]);
+
+        // ── Pan servo mount holes (4× M3 in rectangular pattern) ─────────
+        for (sx = [-SERVO_HOLE_X, SERVO_HOLE_X])
+        for (sy = [-SERVO_HOLE_Y, SERVO_HOLE_Y])
+            translate([sx, -BASE_T + 6 + e, BASE_H/2 + sy])
+                rotate([90, 0, 0])
+                    cylinder(d = SERVO_M3_D, h = BASE_T + 2*e);
+
+        // ── Pan servo shaft bore (passes shaft through base if needed) ────
+        // Centre of shaft at Z = BASE_H/2, no bore needed (shaft exits top)
+
+        // ── Lightening pockets ────────────────────────────────────────────
+        translate([0, -BASE_T/2 + 3, BASE_H/2])
+            cube([BASE_W - 14, BASE_T - 4, BASE_H - 14], center = true);
+    }
+}
+
+// ============================================================
+// PART 2 — PAN YOKE
+// ============================================================
+// U-shaped yoke that attaches to pan servo horn (below) and carries
+// the tilt axis (above).  Two vertical arms straddle the camera cradle.
+// Tilt servo sits on top of one arm; tilt pivot boss on the other.
+//
+// Yoke base bolts to pan servo horn (4× M3 on HORN_BC_D bolt circle).
+// Pan servo horn spline bore passes through yoke base centre.
+// Tilt axis: M4 pivot axle through boss on each arm (X-axis rotation).
+//
+// Print: upright (yoke in final orientation), PETG, 5 perims, 40% gyroid.
+module pan_yoke() {
+    arm_z_total = YOKE_ARM_H + YOKE_BASE_T;
+    inner_w     = YOKE_INNER_W;
+
+    difference() {
+        union() {
+            // ── Yoke base plate (bolts to pan servo horn) ─────────────────
+            translate([-inner_w/2 - YOKE_WALL_T, 0, 0])
+                cube([inner_w + 2*YOKE_WALL_T, YOKE_BASE_T, YOKE_BASE_T]);
+
+            // ── Left arm ──────────────────────────────────────────────────
+            translate([-inner_w/2 - YOKE_WALL_T, 0, 0])
+                cube([YOKE_WALL_T, YOKE_BASE_T, arm_z_total]);
+
+            // ── Right arm (tilt servo side) ───────────────────────────────
+            translate([inner_w/2, 0, 0])
+                cube([YOKE_WALL_T, YOKE_BASE_T, arm_z_total]);
+
+            // ── Tilt pivot bosses (both arms, X-axis) ─────────────────────
+            // Left pivot boss (plain pivot — M4 bolt)
+            translate([-inner_w/2 - YOKE_WALL_T - PIVOT_BOSS_L,
+                       YOKE_BASE_T/2,
+                       YOKE_BASE_T + YOKE_ARM_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d = PIVOT_BOSS_D, h = PIVOT_BOSS_L + YOKE_WALL_T);
+
+            // Right pivot boss (tilt servo horn seat)
+            translate([inner_w/2,
+                       YOKE_BASE_T/2,
+                       YOKE_BASE_T + YOKE_ARM_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d = PIVOT_BOSS_D + 4, h = PIVOT_BOSS_L + YOKE_WALL_T);
+
+            // ── Tilt servo body seat on right arm top ─────────────────────
+            translate([inner_w/2, 0, arm_z_total - SERVO_H - 4])
+                cube([YOKE_WALL_T + SERVO_D + 2, YOKE_BASE_T, SERVO_H + 4]);
+        }
+
+        // ── Pan horn spline bore (centre of yoke base) ────────────────────
+        translate([0, YOKE_BASE_T/2, YOKE_BASE_T/2])
+            rotate([90, 0, 0])
+                cylinder(d = HORN_SPLINE_D, h = YOKE_BASE_T + 2*e,
+                         center = true);
+
+        // ── Pan horn bolt holes (4× M3 on HORN_BC_D) ─────────────────────
+        for (a = [45, 135, 225, 315])
+            translate([HORN_BC_D/2 * cos(a),
+                       YOKE_BASE_T/2,
+                       HORN_BC_D/2 * sin(a) + YOKE_BASE_T/2])
+                rotate([90, 0, 0])
+                    cylinder(d = HORN_BOLT_D, h = YOKE_BASE_T + 2*e,
+                             center = true);
+
+        // ── Left tilt pivot bore (M4 clearance) ───────────────────────────
+        translate([-inner_w/2 - YOKE_WALL_T - PIVOT_BOSS_L - e,
+                   YOKE_BASE_T/2,
+                   YOKE_BASE_T + YOKE_ARM_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = PIVOT_D, h = PIVOT_BOSS_L + YOKE_WALL_T + 2*e);
+
+        // ── Right tilt pivot bore (larger — tilt horn plate seats here) ───
+        translate([inner_w/2 - e,
+                   YOKE_BASE_T/2,
+                   YOKE_BASE_T + YOKE_ARM_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = HORN_SPLINE_D,
+                         h = PIVOT_BOSS_L + YOKE_WALL_T + 2*e);
+
+        // ── Tilt servo mount holes in right arm seat ──────────────────────
+        for (sz = [-SERVO_HOLE_Y, SERVO_HOLE_Y])
+            translate([inner_w/2 + YOKE_WALL_T + SERVO_D/2,
+                       YOKE_BASE_T/2,
+                       arm_z_total - SERVO_H/2 + sz])
+                rotate([90, 0, 0])
+                    cylinder(d = SERVO_M3_D, h = YOKE_BASE_T + 2*e,
+                             center = true);
+
+        // ── M3 nut pockets (tilt servo mount, rear of arm seat) ──────────
+        for (sz = [-SERVO_HOLE_Y, SERVO_HOLE_Y])
+            translate([inner_w/2 + YOKE_WALL_T + SERVO_D/2,
+                       YOKE_BASE_T - M3_NUT_H - 0.5,
+                       arm_z_total - SERVO_H/2 + sz])
+                rotate([90, 0, 0])
+                    cylinder(d = M3_NUT_AF / cos(30), h = M3_NUT_H + 0.5,
+                             $fn = 6);
+
+        // ── Lightening slots in yoke arms ─────────────────────────────────
+        translate([-inner_w/2 - YOKE_WALL_T/2,
+                   YOKE_BASE_T/2,
+                   YOKE_BASE_T + YOKE_ARM_H/2 - 10])
+            cube([YOKE_WALL_T - 2, YOKE_BASE_T - 2, YOKE_ARM_H - 24],
+                 center = true);
+        translate([inner_w/2 + YOKE_WALL_T/2,
+                   YOKE_BASE_T/2,
+                   YOKE_BASE_T + YOKE_ARM_H/2 - 10])
+            cube([YOKE_WALL_T - 2, YOKE_BASE_T - 2, YOKE_ARM_H - 30],
+                 center = true);
+    }
+}
+
+// ============================================================
+// PART 3 — TILT HORN PLATE
+// ============================================================
+// Disc plate bolting to tilt ST3215 servo horn on the right yoke arm.
+// Servo horn spline centres into disc bore (captured, no free rotation).
+// Camera cradle attaches to opposite face via 2× M3 bolts.
+//
+// Tilt range: ±45° limited by yoke arm geometry.
+// Plate thickness HORN_PLATE_T provides stiffness for cantilevered cradle.
+//
+// Print: flat (disc face down), PETG, 5 perims, 50 % infill.
+module tilt_horn_plate() {
+    plate_od = HORN_OD + 8;   // plate OD (4 mm rim outside horn BC)
+
+    difference() {
+        union() {
+            // ── Main disc ─────────────────────────────────────────────────
+            cylinder(d = plate_od, h = HORN_PLATE_T);
+
+            // ── Cradle attachment arm (extends to camera cradle) ──────────
+            // Rectangular boss on top of disc toward camera
+            translate([-CAM_W/2, HORN_PLATE_T - e, -CAM_H/2])
+                cube([CAM_W, HORN_PLATE_T + 4, CAM_H]);
+        }
+
+        // ── Servo horn spline bore (centre) ───────────────────────────────
+        translate([0, 0, -e])
+            cylinder(d = HORN_SPLINE_D, h = HORN_PLATE_T + 2*e);
+
+        // ── Horn bolt holes (4× M3 on HORN_BC_D) ─────────────────────────
+        for (a = [45, 135, 225, 315])
+            translate([HORN_BC_D/2 * cos(a),
+                       HORN_BC_D/2 * sin(a), -e])
+                cylinder(d = HORN_BOLT_D, h = HORN_PLATE_T + 2*e);
+
+        // ── Pivot axle bore (M4, coaxial with horn centre) ────────────────
+        translate([0, 0, -e])
+            cylinder(d = PIVOT_D, h = HORN_PLATE_T + 2*e);
+
+        // ── Cradle attachment bolts (2× M3 in arm boss) ──────────────────
+        for (cz = [-CAM_H/2 + 6, CAM_H/2 - 6])
+            translate([0, HORN_PLATE_T + 2, cz])
+                rotate([90, 0, 0])
+                    cylinder(d = M3_D, h = HORN_PLATE_T + 6 + 2*e);
+
+        // ── M3 hex nut pockets (rear of disc face) ────────────────────────
+        for (cz = [-CAM_H/2 + 6, CAM_H/2 - 6])
+            translate([0, M3_NUT_H + 0.5, cz])
+                rotate([90, 0, 0])
+                    cylinder(d = M3_NUT_AF / cos(30),
+                             h = M3_NUT_H + 0.5, $fn = 6);
+
+        // ── Weight-relief arcs (between horn bolt holes) ──────────────────
+        for (a = [0, 90, 180, 270])
+            translate([(plate_od/2 - 5) * cos(a),
+                       (plate_od/2 - 5) * sin(a), -e])
+                cylinder(d = 6, h = HORN_PLATE_T + 2*e);
+    }
+}
+
+// ============================================================
+// PART 4 — CAMERA CRADLE
+// ============================================================
+// Open-front U-cradle holding D435i via captured 1/4-20 hex nut.
+// Front lip retains camera from sliding forward (+Y).
+// Vibration-damping pads seat in recessed pockets on inner faces.
+// USB-C cable routing channel exits cradle right rear wall.
+//
+// 1/4-20 captured nut in cradle floor — tighten with standard
+// tripod screw or M6→1/4-20 adapter from camera bottom.
+//
+// Print: cradle-floor-down (flat), PETG, 5 perims, 40 % gyroid.
+// No supports needed (overhangs < 45°).
+module camera_cradle() {
+    outer_w = CAM_W + 2*CRADLE_WALL_T;
+    outer_h = CAM_H + CRADLE_FLOOR_T;
+
+    difference() {
+        union() {
+            // ── Cradle body ───────────────────────────────────────────────
+            translate([-outer_w/2, 0, 0])
+                cube([outer_w, CAM_D + CRADLE_WALL_T, outer_h]);
+
+            // ── Front retaining lip ───────────────────────────────────────
+            translate([-outer_w/2, CAM_D + CRADLE_WALL_T - CRADLE_LIP_T, 0])
+                cube([outer_w, CRADLE_LIP_T, CRADLE_LIP_H]);
+
+            // ── Cable channel boss (right rear, exits +X side) ────────────
+            translate([CAM_W/2 + CRADLE_WALL_T - e,
+                       0,
+                       CRADLE_FLOOR_T + CAM_H/2 - CABLE_CH_H/2])
+                cube([CABLE_CH_W + CRADLE_WALL_T, CAM_D * 0.6, CABLE_CH_H]);
+
+            // ── Tilt horn attachment tabs (left + right, bolt to horn plate)─
+            for (sx = [-outer_w/2 - 4, outer_w/2])
+                translate([sx, CAM_D/2, CRADLE_FLOOR_T + CAM_H/2 - 6])
+                    cube([4, 12, 12]);
+        }
+
+        // ── Camera pocket (hollow interior) ──────────────────────────────
+        translate([-CAM_W/2, 0, CRADLE_FLOOR_T])
+            cube([CAM_W, CAM_D + CRADLE_WALL_T + e, CAM_H + e]);
+
+        // ── 1/4-20 UNC clearance bore (camera tripod thread, bottom) ─────
+        translate([CAM_MOUNT_X, CAM_MOUNT_Y, -e])
+            cylinder(d = QTR20_D, h = CRADLE_FLOOR_T + 2*e);
+
+        // ── 1/4-20 hex nut pocket (captured in cradle floor) ─────────────
+        translate([CAM_MOUNT_X, CAM_MOUNT_Y, CRADLE_FLOOR_T - QTR20_NUT_H - 0.5])
+            cylinder(d = QTR20_NUT_AF / cos(30),
+                     h = QTR20_NUT_H + 0.6, $fn = 6);
+
+        // ── USB-C cable channel (exit through right rear wall) ────────────
+        translate([CAM_W/2 - e,
+                   0,
+                   CRADLE_FLOOR_T + CAM_H/2 - CABLE_CH_H/2])
+            cube([CABLE_CH_W + CRADLE_WALL_T + 2*e,
+                  CAM_D * 0.6 + e, CABLE_CH_H]);
+
+        // ── Vibe pad recesses on inner camera-contact faces ───────────────
+        // Rear wall recess (camera front face → +Y side of rear wall)
+        translate([-CAM_W/2 + CRADLE_WALL_T, CRADLE_WALL_T, CRADLE_FLOOR_T])
+            cube([CAM_W, PAD_T, CAM_H]);
+
+        // ── Tilt horn bolt holes in attachment tabs ───────────────────────
+        for (sx = [-outer_w/2 - 4 - e, outer_w/2 - e])
+            translate([sx, CAM_D/2 + 6, CRADLE_FLOOR_T + CAM_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d = M3_D, h = 6 + 2*e);
+
+        // ── M3 nut pockets in attachment tabs ─────────────────────────────
+        translate([outer_w/2 + 4 - M3_NUT_H - 0.4,
+                   CAM_D/2 + 6,
+                   CRADLE_FLOOR_T + CAM_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = M3_NUT_AF / cos(30),
+                         h = M3_NUT_H + 0.4, $fn = 6);
+        translate([-outer_w/2 - 4 - e,
+                   CAM_D/2 + 6,
+                   CRADLE_FLOOR_T + CAM_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = M3_NUT_AF / cos(30),
+                         h = M3_NUT_H + 0.4, $fn = 6);
+
+        // ── Lightening pockets in cradle walls ────────────────────────────
+        for (face_x = [-CAM_W/2 - CRADLE_WALL_T - e, CAM_W/2 - e])
+            translate([face_x, CAM_D * 0.2, CRADLE_FLOOR_T + 3])
+                cube([CRADLE_WALL_T + 2*e, CAM_D * 0.55, CAM_H - 6]);
+    }
+}
+
+// ============================================================
+// PART 5 — VIBRATION-DAMPING PAD
+// ============================================================
+// Flat pad with transverse PETG flexure ribs pressing against camera body.
+// Rib geometry (thin fins ~1.5 mm tall) deflects under camera vibration,
+// attenuating high-frequency input from motor/drive-train.
+// For superior damping: print in TPU 95A (no infill changes needed).
+// Pads seat in recessed pockets in camera cradle inner wall.
+// Optional M2 bolt-through at corners or adhesive-back foam tape.
+//
+// Print: pad-back-face-down, PETG or TPU 95A, 3 perims, 20 % infill.
+module vibe_pad() {
+    rib_count = floor((PAD_W - RIB_W) / RIB_PITCH);
+
+    union() {
+        // ── Base plate ────────────────────────────────────────────────────
+        translate([-PAD_W/2, -PAD_T, -PAD_H/2])
+            cube([PAD_W, PAD_T, PAD_H]);
+
+        // ── Flexure ribs (parallel to Z, spaced RIB_PITCH apart) ─────────
+        for (i = [0 : rib_count - 1]) {
+            rx = -PAD_W/2 + RIB_PITCH/2 + i * RIB_PITCH + RIB_W/2;
+            if (rx <= PAD_W/2 - RIB_W/2)
+                translate([rx, 0, 0])
+                    cube([RIB_W, RIB_H, PAD_H - 6], center = true);
+        }
+
+        // ── Corner nubs (M2 bolt-through retention, optional) ─────────────
+        for (px = [-PAD_W/2 + 5, PAD_W/2 - 5])
+        for (pz = [-PAD_H/2 + 5, PAD_H/2 - 5])
+            translate([px, -PAD_T/2, pz])
+                difference() {
+                    cylinder(d = 5, h = PAD_T, center = true);
+                    cylinder(d = 2.4, h = PAD_T + 2*e, center = true);
+                }
+    }
+}

chassis/ip54_BOM.md

@@ -104,7 +104,11 @@ IP54-rated enclosures and sensor housings for all-weather outdoor robot operatio
 | Component | Thermal strategy | Max junction | Enclosure budget |
 |-----------|-----------------|-------------|-----------------|
 | Jetson Orin NX | Al pad → lid → fan forced convection | 95 °C Tj | Target ≤ 60 °C case |
-| FC (MAMBA F722S) | Passive; FC has own EMI shield | 85 °C | <60 °C ambient OK |
+<<<<<<< HEAD
+| FC (ESP32 BALANCE) | Passive; FC has own EMI shield | 85 °C | <60 °C ambient OK |
+=======
+| FC (ESP32-S3 BALANCE) | Passive; FC has own EMI shield | 85 °C | <60 °C ambient OK |
+>>>>>>> 291dd68 (feat: remove all STM32/Mamba/BlackPill references — ESP32-S3 only)
 | ESC × 2 | Al pad → lid | 100 °C Tj | Target ≤ 60 °C |
 | D435i | Passive; housing vent gap on rear cap | 45 °C surface | — |
 

chassis/jetson_orin_mount.scad

@@ -0,0 +1,386 @@
+// ============================================================
+// Jetson Orin Nano Carrier Board Mount — Issue #612
+// Agent   : sl-mechanical
+// Date    : 2026-03-15
+// Part catalogue:
+//   1. tnut_base     — 2020 T-slot rail interface plate, M5 T-nut captive pockets
+//   2. standoff_post — M2.5 captive-nut standoff post (×4), 10 mm airflow gap
+//   3. side_brace    — lateral stiffening brace with port-access cutouts (×2)
+//   4. duct_shroud   — optional top heatsink duct / fan-exhaust channel
+//   5. cable_clip    — snap-on cable management clip for brace edge
+//
+// BOM:
+//   4 × M5×10 BHCS + M5 T-nuts          (tnut_base to rail, 2 per rail)
+//   4 × M2.5×20 SHCS                    (board to standoff posts)
+//   4 × M2.5 hex nuts                   (captured in standoff posts)
+//   4 × M3×8  SHCS + washers            (side_brace to tnut_base)
+//   2 × M3×16 SHCS                      (duct_shroud to side_brace tops)
+//
+// Jetson Orin Nano carrier board (Seeed reComputer / official dev kit):
+//   Board dims   : 100 × 80 mm
+//   Mounting hole pattern : 86 × 58 mm (centre-to-centre), M2.5, Ø3.5 pad
+//   PCB thickness: 1.6 mm
+//   Connector side: -Y (USB-A, USB-C, HDMI, DP, GbE, SD on one long edge)
+//   Fan header & PWM header: +X short edge
+//   M.2 / NVMe: bottom face
+//
+// Print settings (PETG):
+//   tnut_base / standoff_post / side_brace / duct_shroud : 5 perimeters, 40 % gyroid, no supports
+//   cable_clip                                            : 3 perimeters, 30 % gyroid, no supports
+//
+// Export commands:
+//   openscad -D 'RENDER="tnut_base"'     -o tnut_base.stl     jetson_orin_mount.scad
+//   openscad -D 'RENDER="standoff_post"' -o standoff_post.stl jetson_orin_mount.scad
+//   openscad -D 'RENDER="side_brace"'    -o side_brace.stl    jetson_orin_mount.scad
+//   openscad -D 'RENDER="duct_shroud"'   -o duct_shroud.stl   jetson_orin_mount.scad
+//   openscad -D 'RENDER="cable_clip"'    -o cable_clip.stl    jetson_orin_mount.scad
+//   openscad -D 'RENDER="assembly"'      -o assembly.png      jetson_orin_mount.scad
+// ============================================================
+
+// ── Render selector ─────────────────────────────────────────
+RENDER = "assembly"; // tnut_base | standoff_post | side_brace | duct_shroud | cable_clip | assembly
+
+// ── Global constants ────────────────────────────────────────
+$fn = 64;
+EPS = 0.01;
+
+// 2020 rail
+RAIL_W      = 20.0;
+SLOT_NECK_H =  3.2;
+TNUT_W      =  9.8;
+TNUT_H      =  5.5;
+TNUT_L      = 12.0;
+M5_D        =  5.2;
+M5_HEAD_D   =  9.5;
+M5_HEAD_H   =  4.0;
+
+// Jetson Orin Nano carrier board
+BOARD_L     = 100.0;  // board X
+BOARD_W     =  80.0;  // board Y
+BOARD_T     =   1.6;  // PCB thickness
+MH_SX       =  86.0;  // mounting hole span X (centre-to-centre)
+MH_SY       =  58.0;  // mounting hole span Y
+M25_D       =   2.7;  // M2.5 clearance bore
+M25_NUT_W   =   5.0;  // M2.5 hex nut across-flats
+M25_NUT_H   =   2.0;  // M2.5 hex nut height
+M25_HEAD_D  =   5.0;  // M2.5 SHCS head diameter
+M25_HEAD_H  =   2.5;
+
+// Base plate
+BASE_L      = 120.0;  // length along X (covers board + overhang for braces)
+BASE_W      =  50.0;  // width along Y (rail mount footprint)
+BASE_T      =   6.0;  // plate thickness
+BOLT_PITCH  =  40.0;  // M5 rail bolt pitch (per rail, 2 rails at Y=0 & Y=BASE_W)
+M3_D        =   3.2;
+M3_HEAD_D   =   6.0;
+M3_HEAD_H   =   3.0;
+
+// Standoff posts
+POST_H      =  12.0;  // airflow gap + PCB seating (>= 10 mm clearance spec)
+POST_OD     =   8.0;  // outer diameter
+POST_BASE_D =  11.0;  // flange diameter
+POST_BASE_H =   3.0;  // flange height
+NUT_TRAP_H  = M25_NUT_H + 0.3;
+NUT_TRAP_W  = M25_NUT_W + 0.4;
+
+// Side braces
+BRACE_T     =   5.0;  // brace thickness (X)
+BRACE_H     = POST_H + POST_BASE_H + BOARD_T + 4.0;  // full height
+BRACE_W     = BASE_W;  // same width as base
+
+// Port-access cutouts (connector side -Y)
+USB_CUT_W   =  60.0;  // wide cutout for USB-A stack + HDMI + DP
+USB_CUT_H   =  22.0;
+GBE_CUT_W   =  20.0;  // GbE jack
+GBE_CUT_H   =  18.0;
+
+// Duct shroud
+DUCT_T      =   3.0;  // wall thickness
+DUCT_FLANGE =   6.0;  // side tab width for M3 attachment
+FAN_W       =  40.0;  // standard 40 mm blower clearance cutout
+FAN_H       =  10.0;  // duct outlet height
+
+// Cable clip
+CLIP_OD     =  12.0;
+CLIP_ID     =   7.0;
+CLIP_GAP    =   7.5;
+CLIP_W      =  10.0;
+SNAP_T      =   1.8;
+
+// ── Utilities ───────────────────────────────────────────────
+module chamfer_cube(size, ch=1.0) {
+    hull() {
+        translate([ch, ch, 0])          cube([size[0]-2*ch, size[1]-2*ch, EPS]);
+        translate([0, 0, ch])           cube(size - [0, 0, ch]);
+    }
+}
+
+module hex_pocket(af, depth) {
+    cylinder(d=af/cos(30), h=depth, $fn=6);
+}
+
+// ── Part 1: tnut_base ───────────────────────────────────────
+module tnut_base() {
+    difference() {
+        union() {
+            chamfer_cube([BASE_L, BASE_W, BASE_T], ch=1.5);
+
+            // Raised mounting bosses for M3 brace attachment (4 corners)
+            for (x = [8, BASE_L-8])
+                for (y = [8, BASE_W-8])
+                    translate([x, y, BASE_T])
+                        cylinder(d=10, h=2.5);
+        }
+
+        // T-nut pockets and M5 bolts — front rail (y = BASE_W/4)
+        for (x = [BASE_L/2 - BOLT_PITCH/2, BASE_L/2 + BOLT_PITCH/2]) {
+            translate([x, BASE_W/4, -EPS]) {
+                cylinder(d=M5_D, h=BASE_T + 2*EPS);
+                cylinder(d=M5_HEAD_D, h=M5_HEAD_H + EPS);
+            }
+            translate([x - TNUT_L/2, BASE_W/4 - TNUT_W/2, BASE_T - TNUT_H])
+                cube([TNUT_L, TNUT_W, TNUT_H + EPS]);
+        }
+
+        // T-nut pockets and M5 bolts — rear rail (y = 3*BASE_W/4)
+        for (x = [BASE_L/2 - BOLT_PITCH/2, BASE_L/2 + BOLT_PITCH/2]) {
+            translate([x, 3*BASE_W/4, -EPS]) {
+                cylinder(d=M5_D, h=BASE_T + 2*EPS);
+                cylinder(d=M5_HEAD_D, h=M5_HEAD_H + EPS);
+            }
+            translate([x - TNUT_L/2, 3*BASE_W/4 - TNUT_W/2, BASE_T - TNUT_H])
+                cube([TNUT_L, TNUT_W, TNUT_H + EPS]);
+        }
+
+        // M3 boss bolt holes (corner braces)
+        for (x = [8, BASE_L-8])
+            for (y = [8, BASE_W-8])
+                translate([x, y, -EPS])
+                    cylinder(d=M3_D, h=BASE_T + 2.5 + 2*EPS);
+
+        // M3 boss counterbores (head from bottom)
+        for (x = [8, BASE_L-8])
+            for (y = [8, BASE_W-8])
+                translate([x, y, -EPS])
+                    cylinder(d=M3_HEAD_D, h=M3_HEAD_H + EPS);
+
+        // Standoff post seating holes (board hole pattern, centred on plate)
+        bx0 = BASE_L/2 - MH_SX/2;
+        by0 = BASE_W/2 - MH_SY/2;
+        for (dx = [0, MH_SX])
+            for (dy = [0, MH_SY])
+                translate([bx0+dx, by0+dy, -EPS])
+                    cylinder(d=POST_BASE_D + 0.4, h=BASE_T + 2*EPS);
+
+        // Weight relief grid (2 pockets)
+        translate([20, 12, -EPS]) cube([30, BASE_W-24, BASE_T/2]);
+        translate([BASE_L-50, 12, -EPS]) cube([30, BASE_W-24, BASE_T/2]);
+
+        // Cable pass-through slot
+        translate([BASE_L/2 - 8, BASE_W/2 - 3, -EPS])
+            cube([16, 6, BASE_T + 2*EPS]);
+    }
+}
+
+// ── Part 2: standoff_post ───────────────────────────────────
+module standoff_post() {
+    difference() {
+        union() {
+            // Flange
+            cylinder(d=POST_BASE_D, h=POST_BASE_H);
+            // Post body
+            translate([0, 0, POST_BASE_H])
+                cylinder(d=POST_OD, h=POST_H);
+        }
+
+        // M2.5 through bore
+        translate([0, 0, -EPS])
+            cylinder(d=M25_D, h=POST_BASE_H + POST_H + 2*EPS);
+
+        // Captured hex nut trap (from top)
+        translate([0, 0, POST_BASE_H + POST_H - NUT_TRAP_H])
+            hex_pocket(NUT_TRAP_W, NUT_TRAP_H + EPS);
+
+        // Anti-rotation flat on nut pocket
+        translate([-M25_NUT_W/2 - 0.2, -POST_OD/2 - EPS,
+                   POST_BASE_H + POST_H - NUT_TRAP_H])
+            cube([M25_NUT_W + 0.4, 2.0, NUT_TRAP_H + EPS]);
+    }
+}
+
+// ── Part 3: side_brace ──────────────────────────────────────
+// Printed as +X face. Mirror for -X side.
+module side_brace() {
+    difference() {
+        union() {
+            chamfer_cube([BRACE_T, BRACE_W, BRACE_H], ch=1.0);
+
+            // Top lip to retain board edge
+            translate([0, 0, BRACE_H])
+                cube([BRACE_T + 8.0, BRACE_W, 2.5]);
+        }
+
+        // M3 bolt holes at base (attach to tnut_base bosses)
+        for (y = [8, BRACE_W-8])
+            translate([-EPS, y, 4])
+                rotate([0, 90, 0])
+                    cylinder(d=M3_D, h=BRACE_T + 2*EPS);
+
+        // M3 counterbore from outer face
+        for (y = [8, BRACE_W-8])
+            translate([-EPS, y, 4])
+                rotate([0, 90, 0])
+                    cylinder(d=M3_HEAD_D, h=M3_HEAD_H + EPS);
+
+        // Port-access cutout — USB/HDMI/DP cluster (centred on brace face)
+        translate([-EPS, BRACE_W/2 - USB_CUT_W/2, POST_BASE_H + 2.0])
+            cube([BRACE_T + 2*EPS, USB_CUT_W, USB_CUT_H]);
+
+        // GbE cutout (offset toward +Y)
+        translate([-EPS, BRACE_W/2 + USB_CUT_W/2 - GBE_CUT_W - 2, POST_BASE_H + 2.0])
+            cube([BRACE_T + 2*EPS, GBE_CUT_W, GBE_CUT_H]);
+
+        // M3 duct attachment holes (top edge)
+        for (y = [BRACE_W/4, 3*BRACE_W/4])
+            translate([BRACE_T/2, y, BRACE_H - 2])
+                cylinder(d=M3_D, h=10);
+
+        // Ventilation slots (3 tall slots for airflow)
+        for (i = [0:2])
+            translate([-EPS,
+                       (BRACE_W - 3*8 - 2*4) / 2 + i*(8+4),
+                       POST_BASE_H + USB_CUT_H + 6])
+                cube([BRACE_T + 2*EPS, 8, BRACE_H - POST_BASE_H - USB_CUT_H - 10]);
+    }
+}
+
+// ── Part 4: duct_shroud ─────────────────────────────────────
+// Top cap that channels fan exhaust away from board; optional print.
+module duct_shroud() {
+    duct_l = BASE_L - 2*BRACE_T - 1.0;  // span between inner brace faces
+    duct_w = BRACE_W;
+
+    difference() {
+        union() {
+            // Top plate
+            cube([duct_l, duct_w, DUCT_T]);
+
+            // Front wall (fan inlet side)
+            translate([0, 0, -FAN_H])
+                cube([DUCT_T, duct_w, FAN_H + DUCT_T]);
+
+            // Rear wall (exhaust side — open centre)
+            translate([duct_l - DUCT_T, 0, -FAN_H])
+                cube([DUCT_T, duct_w, FAN_H + DUCT_T]);
+
+            // Side flanges for M3 attachment
+            translate([-DUCT_FLANGE, 0, -FAN_H])
+                cube([DUCT_FLANGE, duct_w, FAN_H + DUCT_T]);
+            translate([duct_l, 0, -FAN_H])
+                cube([DUCT_FLANGE, duct_w, FAN_H + DUCT_T]);
+        }
+
+        // Fan cutout on top plate (centred)
+        translate([duct_l/2 - FAN_W/2, duct_w/2 - FAN_W/2, -EPS])
+            cube([FAN_W, FAN_W, DUCT_T + 2*EPS]);
+
+        // Fan screw holes (40 mm fan, Ø3.2 at 32 mm BC)
+        for (dx = [-16, 16])
+            for (dy = [-16, 16])
+                translate([duct_l/2 + dx, duct_w/2 + dy, -EPS])
+                    cylinder(d=M3_D, h=DUCT_T + 2*EPS);
+
+        // Exhaust slot on rear wall (full width minus corners)
+        translate([duct_l - DUCT_T - EPS, 4, -FAN_H + 2])
+            cube([DUCT_T + 2*EPS, duct_w - 8, FAN_H - 2]);
+
+        // M3 flange attachment holes
+        for (y = [duct_w/4, 3*duct_w/4]) {
+            translate([-DUCT_FLANGE - EPS, y, -FAN_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d=M3_D, h=DUCT_FLANGE + 2*EPS);
+            translate([duct_l + DUCT_T - EPS, y, -FAN_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d=M3_D, h=DUCT_FLANGE + 2*EPS);
+        }
+    }
+}
+
+// ── Part 5: cable_clip ──────────────────────────────────────
+module cable_clip() {
+    difference() {
+        union() {
+            // Snap-wrap body
+            difference() {
+                cylinder(d=CLIP_OD + 2*SNAP_T, h=CLIP_W);
+                translate([0, 0, -EPS])
+                    cylinder(d=CLIP_ID, h=CLIP_W + 2*EPS);
+                // Front gap
+                translate([-CLIP_GAP/2, 0, -EPS])
+                    cube([CLIP_GAP, CLIP_OD, CLIP_W + 2*EPS]);
+            }
+
+            // Mounting tab for brace edge
+            translate([CLIP_OD/2 + SNAP_T - EPS, -SNAP_T, 0])
+                cube([8, SNAP_T*2, CLIP_W]);
+        }
+
+        // Tab screw hole
+        translate([CLIP_OD/2 + SNAP_T + 4, 0, CLIP_W/2])
+            rotate([90, 0, 0])
+                cylinder(d=M3_D, h=SNAP_T*2 + 2*EPS, center=true);
+    }
+}
+
+// ── Assembly ────────────────────────────────────────────────
+module assembly() {
+    // Base plate
+    color("SteelBlue")
+        tnut_base();
+
+    // Standoff posts (board hole pattern)
+    bx0 = BASE_L/2 - MH_SX/2;
+    by0 = BASE_W/2 - MH_SY/2;
+    for (dx = [0, MH_SX])
+        for (dy = [0, MH_SY])
+            color("DodgerBlue")
+                translate([bx0+dx, by0+dy, BASE_T])
+                    standoff_post();
+
+    // Side braces (left and right)
+    color("CornflowerBlue")
+        translate([0, 0, BASE_T])
+            side_brace();
+    color("CornflowerBlue")
+        translate([BASE_L, BRACE_W, BASE_T])
+            mirror([1, 0, 0])
+                mirror([0, 1, 0])
+                    side_brace();
+
+    // Board silhouette (translucent, for clearance visualisation)
+    color("ForestGreen", 0.25)
+        translate([BASE_L/2 - BOARD_L/2, BASE_W/2 - BOARD_W/2,
+                   BASE_T + POST_BASE_H + POST_H])
+            cube([BOARD_L, BOARD_W, BOARD_T]);
+
+    // Duct shroud (above board)
+    color("LightSteelBlue", 0.7)
+        translate([BRACE_T + 0.5, 0,
+                   BASE_T + POST_BASE_H + POST_H + BOARD_T + 2.0])
+            duct_shroud();
+
+    // Cable clips (on brace edge, 2×)
+    for (y = [BRACE_W/3, 2*BRACE_W/3])
+        color("SlateGray")
+            translate([BASE_L + 2, y, BASE_T + BRACE_H/2 - CLIP_W/2])
+                rotate([0, 90, 0])
+                    cable_clip();
+}
+
+// ── Dispatch ────────────────────────────────────────────────
+if      (RENDER == "tnut_base")     tnut_base();
+else if (RENDER == "standoff_post") standoff_post();
+else if (RENDER == "side_brace")    side_brace();
+else if (RENDER == "duct_shroud")   duct_shroud();
+else if (RENDER == "cable_clip")    cable_clip();
+else                                assembly();

chassis/phone_mount_bracket.scad

@@ -0,0 +1,504 @@
+// ============================================================
+// phone_mount_bracket.scad — Spring-Loaded Phone Mount for T-Slot Rail
+// Issue: #535  Agent: sl-mechanical  Date: 2026-03-07
+// ============================================================
+//
+// Parametric spring-loaded phone mount that clamps to the 2020 aluminium
+// T-slot sensor rail.  Adjustable phone width 60–85 mm.  Quick-release
+// cam lever for tool-free phone swap.  Vibration-damping flexure ribs
+// on grip pads absorb motor/terrain vibration (PETG compliance).
+//
+// Design overview:
+//   - Fixed jaw + sliding jaw on a 40 mm guide rail (M4 rod)
+//   - Coil spring (Ø8 × 30 mm) compressed between jaw and end-stop —
+//     spring pre-load keeps phone clamped at any width in range
+//   - Cam lever (printed PETG) rotates 90° to release / lock spring
+//   - Anti-vibration flexure ribs on both grip pad faces
+//   - Landscape or portrait orientation: bracket rotates on T-nut base
+//
+// Parts (STL exports):
+//   Part 1 — tnut_base()          Rail attachment base (universal)
+//   Part 2 — fixed_jaw()          Fixed bottom jaw + guide rail bosses
+//   Part 3 — sliding_jaw()        Spring-loaded sliding jaw
+//   Part 4 — cam_lever()          Quick-release cam lever
+//   Part 5 — grip_pad()           Flexure grip pad (print ×2, TPU optional)
+//   Part 6 — assembly_preview()   Full assembly
+//
+// Hardware BOM (per mount):
+//   1× M4 × 60 mm SHCS          guide rod + spring bolt
+//   1× M4 hex nut                end-stop on sliding jaw
+//   1× Ø8 × 30 mm coil spring   ~0.5 N/mm rate (spring clamping)
+//   2× M3 × 16 mm SHCS          T-nut base thumbscrew + arm bolts
+//   1× M3 hex nut                thumbscrew nut in T-nut
+//   4× M2 × 8 mm SHCS           grip pad retention bolts (optional)
+//
+// Dimensions:
+//   Phone width range : PHONE_W_MIN–PHONE_W_MAX (60–85 mm) parametric
+//   Phone thickness   : up to PHONE_THICK_MAX (12 mm) — open-front jaw
+//   Phone height held : GRIP_SPAN (22 mm each jaw) — portrait/landscape
+//   Overall bracket H : ~110 mm  W: ~90 mm  D: ~55 mm
+//
+// Print settings:
+//   Material  : PETG (tnut_base, fixed_jaw, sliding_jaw, cam_lever)
+//               TPU 95A optional for grip_pad (or PETG for rigidity)
+//   Perimeters: 5 (structural parts), 3 (grip_pad)
+//   Infill    : 40 % gyroid (jaws), 20 % (grip_pad)
+//   Supports  : none needed (designed for FDM orientation)
+//   Layer ht  : 0.2 mm
+//
+// Export commands:
+//   openscad phone_mount_bracket.scad -D 'RENDER="tnut_base_stl"'    -o pm_tnut_base.stl
+//   openscad phone_mount_bracket.scad -D 'RENDER="fixed_jaw_stl"'    -o pm_fixed_jaw.stl
+//   openscad phone_mount_bracket.scad -D 'RENDER="sliding_jaw_stl"'  -o pm_sliding_jaw.stl
+//   openscad phone_mount_bracket.scad -D 'RENDER="cam_lever_stl"'    -o pm_cam_lever.stl
+//   openscad phone_mount_bracket.scad -D 'RENDER="grip_pad_stl"'     -o pm_grip_pad.stl
+// ============================================================
+
+$fn = 64;
+e   = 0.01;   // epsilon for boolean clearance
+
+// ── Phone parameters (adjust to target device) ───────────────────────────────
+PHONE_W_MIN    = 60.0;   // narrowest phone width supported (mm)
+PHONE_W_MAX    = 85.0;   // widest phone width supported (mm)
+PHONE_THICK_MAX = 12.0;  // max phone body thickness incl. case (mm)
+
+// ── Rail geometry (must match sensor_rail.scad) ──────────────────────────────
+RAIL_W         = 20.0;
+SLOT_OPEN      =  6.0;
+SLOT_INNER_W   = 10.2;
+SLOT_INNER_H   =  5.8;
+SLOT_NECK_H    =  3.2;
+
+// ── T-nut constants ───────────────────────────────────────────────────────────
+TNUT_W         =  9.8;
+TNUT_H         =  5.5;
+TNUT_L         = 12.0;
+TNUT_M3_NUT_AF =  5.5;
+TNUT_M3_NUT_H  =  2.5;
+TNUT_BOLT_D    =  3.3;   // M3 clearance
+
+// ── Base plate geometry ───────────────────────────────────────────────────────
+BASE_FACE_W  = 30.0;
+BASE_FACE_H  = 25.0;
+BASE_FACE_T  = SLOT_NECK_H + 1.5;
+
+// ── Jaw geometry ─────────────────────────────────────────────────────────────
+JAW_BODY_W   = 88.0;    // jaw outer width (> PHONE_W_MAX for rim)
+JAW_BODY_H   = 28.0;    // jaw height (Z) — phone grip span
+JAW_BODY_T   = 14.0;    // jaw depth (Y) — phone cradled this deep
+JAW_WALL_T   =  4.0;    // jaw side wall thickness
+JAW_LIP_T    =  3.0;    // front retaining lip thickness
+JAW_LIP_H    =  5.0;    // front lip height (retains phone)
+PHONE_POCKET_D = PHONE_THICK_MAX + 0.5;  // pocket depth for phone
+
+// ── Guide rod / spring system ─────────────────────────────────────────────────
+GUIDE_ROD_D  =  4.3;    // M4 clearance bore in sliding jaw
+GUIDE_BOSS_D = 10.0;    // boss OD around guide bore
+GUIDE_BOSS_T =  6.0;    // boss length
+SPRING_OD    =  8.5;    // coil spring OD pocket (spring is Ø8)
+SPRING_L     = 32.0;    // spring pocket length (spring compressed ~22 mm)
+SPRING_SEAT_T =  3.0;   // spring seat wall at end-stop boss
+JAW_TRAVEL   = PHONE_W_MAX - PHONE_W_MIN + 4.0;   // max jaw travel (mm)
+ARM_SPAN     = PHONE_W_MAX + 2 * JAW_WALL_T + 8;  // fixed jaw total width
+
+// ── Cam lever geometry ────────────────────────────────────────────────────────
+CAM_R_MIN    =  5.0;    // cam small radius (engaged / clamped)
+CAM_R_MAX    =  9.0;    // cam large radius (released, spring compressed)
+CAM_THICK    =  8.0;    // cam disc thickness
+CAM_HANDLE_L = 45.0;    // lever arm length
+CAM_HANDLE_W =  8.0;    // lever handle width
+CAM_HANDLE_T =  5.0;    // lever handle thickness
+CAM_BORE_D   =  4.3;    // M4 pivot bore
+CAM_DETENT_D =  3.0;    // detent ball pocket (3 mm bearing)
+
+// ── Grip pad geometry (vibration dampening flexure ribs) ─────────────────────
+PAD_W        = JAW_BODY_W - 2*JAW_WALL_T - 2;  // pad width
+PAD_H        = JAW_BODY_H - 2;                  // pad height
+PAD_T        =  2.5;    // pad body thickness
+RIB_H        =  1.5;    // flexure rib height above pad face
+RIB_W        =  1.2;    // rib width
+RIB_PITCH    =  5.0;    // rib pitch (centre-to-centre)
+RIB_COUNT    = floor(PAD_W / RIB_PITCH) - 1;
+
+// ── Arm geometry (base to jaw body) ──────────────────────────────────────────
+ARM_REACH    = 38.0;    // distance from rail face to jaw centreline (+Y)
+ARM_T        =  4.0;    // arm thickness
+ARM_H        = BASE_FACE_H;
+
+// ── Fasteners ─────────────────────────────────────────────────────────────────
+M2_D = 2.4;
+M3_D = 3.3;
+M4_D = 4.3;
+M4_NUT_AF = 7.0;   // M4 hex nut across-flats
+M4_NUT_H  = 3.2;   // M4 hex nut height
+
+// ============================================================
+// RENDER DISPATCH
+// ============================================================
+RENDER = "assembly";
+
+if      (RENDER == "assembly")        assembly_preview();
+else if (RENDER == "tnut_base_stl")   tnut_base();
+else if (RENDER == "fixed_jaw_stl")   fixed_jaw();
+else if (RENDER == "sliding_jaw_stl") sliding_jaw();
+else if (RENDER == "cam_lever_stl")   cam_lever();
+else if (RENDER == "grip_pad_stl")    grip_pad();
+
+// ============================================================
+// ASSEMBLY PREVIEW
+// ============================================================
+module assembly_preview() {
+    // Ghost rail section (20 × 20 × 200)
+    %color("Silver", 0.30)
+        linear_extrude(200)
+            square([RAIL_W, RAIL_W], center = true);
+
+    // T-nut base at Z=80 on rail
+    color("OliveDrab", 0.85)
+        translate([0, 0, 80])
+            tnut_base();
+
+    // Fixed jaw assembly (centred, extending +Y from base)
+    color("DarkSlateGray", 0.85)
+        translate([0, SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
+            fixed_jaw();
+
+    // Sliding jaw — shown at mid-travel (phone ~72 mm wide)
+    color("SteelBlue", 0.85)
+        translate([PHONE_W_MIN + (PHONE_W_MAX - PHONE_W_MIN)/2,
+                   SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
+            sliding_jaw();
+
+    // Grip pads on both jaws
+    color("DimGray", 0.85) {
+        translate([0, SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
+            translate([JAW_WALL_T, JAW_BODY_T, JAW_BODY_H/2])
+                rotate([90, 0, 0])
+                    grip_pad();
+        translate([PHONE_W_MIN + (PHONE_W_MAX - PHONE_W_MIN)/2,
+                   SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
+            translate([-JAW_WALL_T - PAD_T, JAW_BODY_T, JAW_BODY_H/2])
+                rotate([90, 0, 180])
+                    grip_pad();
+    }
+
+    // Cam lever — shown in locked (clamped) position
+    color("OrangeRed", 0.85)
+        translate([ARM_SPAN/2 + 6,
+                   SLOT_NECK_H + BASE_FACE_T + ARM_REACH + GUIDE_BOSS_D/2,
+                   80 + JAW_BODY_H/2])
+            rotate([0, 0, 0])
+                cam_lever();
+}
+
+// ============================================================
+// PART 1 — T-NUT BASE
+// ============================================================
+// Standard 2020 T-slot rail attachment base.
+// Identical interface to sensor_rail_brackets.scad universal_tnut_base().
+// Arm extends in +Y; rail clamp bolt in -Y face.
+//
+// Print flat (face plate down), PETG, 5 perims, 60 % infill.
+module tnut_base() {
+    difference() {
+        union() {
+            // Face plate (flush against rail outer face)
+            translate([-BASE_FACE_W/2, -BASE_FACE_T, 0])
+                cube([BASE_FACE_W, BASE_FACE_T, BASE_FACE_H]);
+
+            // T-nut neck (enters rail slot)
+            translate([-TNUT_W/2, 0, (BASE_FACE_H - TNUT_L)/2])
+                cube([TNUT_W, SLOT_NECK_H + e, TNUT_L]);
+
+            // T-nut body (wider, inside T-groove)
+            translate([-TNUT_W/2, SLOT_NECK_H - e, (BASE_FACE_H - TNUT_L)/2])
+                cube([TNUT_W, TNUT_H - SLOT_NECK_H + e, TNUT_L]);
+
+            // Arm stub (face plate → jaw)
+            translate([-BASE_FACE_W/2, -BASE_FACE_T, 0])
+                cube([BASE_FACE_W, BASE_FACE_T + ARM_REACH, ARM_T]);
+        }
+
+        // M3 rail clamp bolt bore (centre of T-nut, through face plate)
+        translate([0, -BASE_FACE_T - e, BASE_FACE_H/2])
+            rotate([-90, 0, 0])
+                cylinder(d = TNUT_BOLT_D, h = BASE_FACE_T + TNUT_H + 2*e);
+
+        // M3 hex nut pocket (inside T-nut body)
+        translate([0, SLOT_NECK_H + 0.3, BASE_FACE_H/2])
+            rotate([-90, 0, 0])
+                cylinder(d = TNUT_M3_NUT_AF / cos(30),
+                         h = TNUT_M3_NUT_H + 0.3,
+                         $fn = 6);
+
+        // 2× M3 bolt holes for arm-to-jaw bolting
+        for (bx = [-10, 10])
+            translate([bx, ARM_REACH - BASE_FACE_T - e, ARM_T/2])
+                rotate([-90, 0, 0])
+                    cylinder(d = M3_D, h = 8 + 2*e);
+
+        // Lightening slot in arm
+        translate([0, -BASE_FACE_T/2 + ARM_REACH/2, ARM_T/2])
+            cube([BASE_FACE_W - 12, ARM_REACH - 16, ARM_T + 2*e],
+                 center = true);
+    }
+}
+
+// ============================================================
+// PART 2 — FIXED JAW
+// ============================================================
+// Fixed lower jaw of the clamping system.  Phone sits in the pocket
+// formed by the fixed jaw (bottom) and sliding jaw (top).
+// Two guide bosses on the right wall carry the M4 guide rod + spring.
+// The cam lever pivot boss is on the outer right face.
+//
+// Coordinate origin: centre-bottom of jaw body.
+// Phone entry face: +Y (open front), phone pocket opens toward +Y.
+// Fixed jaw left edge is at X = -JAW_BODY_W/2.
+//
+// Print jaw-pocket-face down, PETG, 5 perims, 40 % infill.
+module fixed_jaw() {
+    difference() {
+        union() {
+            // ── Main jaw body ────────────────────────────────────────────
+            translate([-JAW_BODY_W/2, -JAW_BODY_T/2, 0])
+                cube([JAW_BODY_W, JAW_BODY_T, JAW_BODY_H]);
+
+            // ── Front retaining lip (keeps phone from falling forward) ───
+            translate([-JAW_BODY_W/2, JAW_BODY_T/2 - JAW_LIP_T, 0])
+                cube([JAW_BODY_W, JAW_LIP_T, JAW_LIP_H]);
+
+            // ── Guide boss right (outer, carries spring + end-stop) ──────
+            translate([JAW_BODY_W/2, 0, JAW_BODY_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d = GUIDE_BOSS_D, h = GUIDE_BOSS_T);
+
+            // ── Cam lever pivot boss (right face, above guide boss) ──────
+            translate([JAW_BODY_W/2, 0, JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
+                rotate([0, 90, 0])
+                    cylinder(d = CAM_THICK + 4, h = 6);
+
+            // ── Arm attachment bosses (left side, connect to tnut_base) ──
+            for (bx = [-10, 10])
+                translate([bx, -JAW_BODY_T/2 - 8, ARM_T/2])
+                    cylinder(d = 8, h = 8);
+        }
+
+        // ── Phone pocket (open-top U channel centred in jaw) ────────────
+        // Pocket opens toward +Y (front), phone drops in from above.
+        translate([0, -JAW_BODY_T/2 - e,
+                   JAW_LIP_H])
+            cube([JAW_BODY_W - 2*JAW_WALL_T,
+                  PHONE_POCKET_D + JAW_WALL_T,
+                  JAW_BODY_H - JAW_LIP_H + e],
+                 center = [true, false, false]);
+
+        // ── Guide rod bore (M4 clearance, through both guide bosses) ────
+        translate([-JAW_BODY_W/2 - e, 0, JAW_BODY_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = GUIDE_ROD_D,
+                         h = JAW_BODY_W + GUIDE_BOSS_T + 2*e);
+
+        // ── Spring pocket (coaxial with guide rod, in right boss) ────────
+        translate([JAW_BODY_W/2 + e, 0, JAW_BODY_H/2])
+            rotate([0, -90, 0])
+                cylinder(d = SPRING_OD, h = SPRING_L);
+
+        // ── M4 hex nut pocket in spring-seat wall (end-stop nut) ────────
+        translate([JAW_BODY_W/2 + GUIDE_BOSS_T + e, 0, JAW_BODY_H/2])
+            rotate([0, -90, 0])
+                cylinder(d = M4_NUT_AF / cos(30), h = M4_NUT_H + 0.5,
+                         $fn = 6);
+
+        // ── Cam pivot bore (M4 pivot, through pivot boss) ────────────────
+        translate([JAW_BODY_W/2 - e, 0, JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
+            rotate([0, 90, 0])
+                cylinder(d = CAM_BORE_D, h = 6 + 2*e);
+
+        // ── Arm attachment bolt holes (M3, to tnut_base arm stubs) ──────
+        for (bx = [-10, 10])
+            translate([bx, -JAW_BODY_T/2 - 8 - e, ARM_T/2])
+                rotate([-90, 0, 0])
+                    cylinder(d = M3_D, h = 12 + 2*e);
+
+        // ── Grip pad seats (recessed Ø1.5 mm, 2 mm deep, optional) ──────
+        for (pz = [JAW_BODY_H * 0.3, JAW_BODY_H * 0.7])
+        for (px = [-PAD_W/4, PAD_W/4])
+            translate([px, -JAW_BODY_T/2 + PHONE_POCKET_D + 1, pz])
+                rotate([-90, 0, 0])
+                    cylinder(d = M2_D, h = 10);
+
+        // ── Lightening pockets (non-structural core removal) ─────────────
+        translate([0, 0, JAW_BODY_H/2])
+            cube([JAW_BODY_W - 2*JAW_WALL_T - 4,
+                  JAW_BODY_T - 2*JAW_WALL_T,
+                  JAW_BODY_H - JAW_LIP_H - 4],
+                 center = true);
+    }
+}
+
+// ============================================================
+// PART 3 — SLIDING JAW
+// ============================================================
+// Upper clamping jaw.  Slides along the M4 guide rod.
+// Spring pushes this jaw toward the phone (inward).
+// M4 hex nut on the guide rod limits maximum travel (full open).
+// Cam lever pushes on this jaw face to compress spring (release).
+//
+// Coordinate origin same convention as fixed_jaw() for assembly.
+// Jaw slides in +X direction (away from fixed jaw left wall).
+//
+// Print jaw-pocket-face down, PETG, 5 perims, 40 % infill.
+module sliding_jaw() {
+    difference() {
+        union() {
+            // ── Main jaw body ────────────────────────────────────────────
+            translate([-JAW_WALL_T, -JAW_BODY_T/2, 0])
+                cube([JAW_BODY_W/2 + JAW_WALL_T, JAW_BODY_T, JAW_BODY_H]);
+
+            // ── Front retaining lip ──────────────────────────────────────
+            translate([-JAW_WALL_T, JAW_BODY_T/2 - JAW_LIP_T, 0])
+                cube([JAW_BODY_W/2 + JAW_WALL_T, JAW_LIP_T, JAW_LIP_H]);
+
+            // ── Guide boss (carries guide rod, spring butts against face) ─
+            translate([-JAW_WALL_T - GUIDE_BOSS_T, 0, JAW_BODY_H/2])
+                rotate([0, 90, 0])
+                    cylinder(d = GUIDE_BOSS_D, h = GUIDE_BOSS_T);
+
+            // ── Cam follower ear (contacts cam lever) ────────────────────
+            translate([-JAW_WALL_T - 2, 0,
+                       JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
+                cube([4, CAM_THICK + 2, CAM_THICK + 2], center = true);
+        }
+
+        // ── Phone pocket (inner face, contacts phone side) ───────────────
+        translate([-JAW_WALL_T - e, -JAW_BODY_T/2 - e, JAW_LIP_H])
+            cube([JAW_BODY_W/2 - JAW_WALL_T + e,
+                  PHONE_POCKET_D + JAW_WALL_T + 2*e,
+                  JAW_BODY_H - JAW_LIP_H + e]);
+
+        // ── Guide rod bore (M4 clearance through boss + jaw wall) ────────
+        translate([-JAW_WALL_T - GUIDE_BOSS_T - e, 0, JAW_BODY_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = GUIDE_ROD_D,
+                         h = GUIDE_BOSS_T + JAW_WALL_T + 2*e);
+
+        // ── M4 nut pocket (end-stop nut, rear of guide boss) ────────────
+        translate([-JAW_WALL_T - GUIDE_BOSS_T - e, 0, JAW_BODY_H/2])
+            rotate([0, 90, 0])
+                cylinder(d = M4_NUT_AF / cos(30), h = M4_NUT_H + 1,
+                         $fn = 6);
+
+        // ── Cam follower bore (M4 pivot passes through ear) ─────────────
+        translate([-JAW_WALL_T - 2 - e, 0,
+                   JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
+            rotate([0, 90, 0])
+                cylinder(d = CAM_BORE_D, h = 6 + 2*e);
+
+        // ── Grip pad seats ───────────────────────────────────────────────
+        for (pz = [JAW_BODY_H * 0.3, JAW_BODY_H * 0.7])
+        for (px = [JAW_BODY_W/8])
+            translate([px, -JAW_BODY_T/2 + PHONE_POCKET_D + 1, pz])
+                rotate([-90, 0, 0])
+                    cylinder(d = M2_D, h = 10);
+    }
+}
+
+// ============================================================
+// PART 4 — CAM LEVER (QUICK-RELEASE)
+// ============================================================
+// Eccentric cam disc + integral handle lever.
+// Rotates 90° on M4 pivot pin between CLAMPED and RELEASED states:
+//   CLAMPED  : cam small radius (CAM_R_MIN) toward jaw → spring pushes jaw
+//   RELEASED : cam large radius (CAM_R_MAX) toward jaw → compresses spring
+//               by (CAM_R_MAX - CAM_R_MIN) = 4 mm, opening jaw
+//
+// Detent ball pocket (Ø3 mm) snaps into rail-dimple for each position.
+// Handle points rearward (-Y) in clamped state for low profile.
+//
+// Print standing on cam edge (cam disc vertical), PETG, 5 perims, 40%.
+module cam_lever() {
+    cam_offset = (CAM_R_MAX - CAM_R_MIN) / 2;   // 2 mm eccentricity
+    union() {
+        difference() {
+            union() {
+                // ── Eccentric cam disc ───────────────────────────────────
+                // Offset so pivot bore is eccentric to disc profile
+                translate([cam_offset, 0, 0])
+                    cylinder(r = CAM_R_MAX, h = CAM_THICK, center = true);
+
+                // ── Lever handle arm ─────────────────────────────────────
+                hull() {
+                    translate([cam_offset, 0, 0])
+                        cylinder(r = CAM_R_MAX, h = CAM_THICK, center = true);
+                    translate([cam_offset + CAM_HANDLE_L, 0, 0])
+                        cylinder(r = CAM_HANDLE_W/2,
+                                 h = CAM_HANDLE_T, center = true);
+                }
+            }
+
+            // ── M4 pivot bore (through cam centre) ───────────────────────
+            cylinder(d = CAM_BORE_D, h = CAM_THICK + 2*e, center = true);
+
+            // ── Detent pockets (2× Ø3 mm, at 0° and 90°) ────────────────
+            // Pocket at 0° → clamped detent
+            translate([CAM_R_MAX - 2, 0, CAM_THICK/2 - 1.5])
+                cylinder(d = CAM_DETENT_D + 0.2, h = 2);
+            // Pocket at 90° → released detent
+            translate([0, CAM_R_MAX - 2, CAM_THICK/2 - 1.5])
+                cylinder(d = CAM_DETENT_D + 0.2, h = 2);
+
+            // ── Lightening recesses on cam disc face ─────────────────────
+            for (a = [0, 60, 120, 180, 240, 300])
+                translate([cam_offset + (CAM_R_MAX - 4) * cos(a),
+                           (CAM_R_MAX - 4) * sin(a), 0])
+                    cylinder(d = 4, h = CAM_THICK + 2*e, center = true);
+
+            // ── Handle grip grooves ──────────────────────────────────────
+            for (i = [0:4])
+                translate([cam_offset + 20 + i * 5, 0, 0])
+                    rotate([90, 0, 0])
+                        cylinder(d = 2.5, h = CAM_HANDLE_W + 2*e,
+                                 center = true);
+        }
+    }
+}
+
+// ============================================================
+// PART 5 — GRIP PAD (VIBRATION DAMPENING)
+// ============================================================
+// Flat pad with transverse flexure ribs that press against phone side.
+// The rib profile (thin PETG fins) provides compliance in Z (vertical)
+// absorbing vibration transmitted through the bracket.
+// Optional: print in TPU 95A for superior damping.
+// M2 bolts or adhesive-backed foam tape attach pad to jaw pocket face.
+//
+// Pad face (+Y) contacts phone.  Mounting face (-Y) bonds to jaw.
+// Ribs run parallel to Z axis (vertical).
+//
+// Print flat (mounting face down), PETG or TPU 95A, 3 perims, 20%.
+module grip_pad() {
+    union() {
+        // ── Base plate ───────────────────────────────────────────────────
+        translate([-PAD_W/2, -PAD_T, -PAD_H/2])
+            cube([PAD_W, PAD_T, PAD_H]);
+
+        // ── Flexure ribs (transverse, dampening in Z) ────────────────────
+        // RIB_COUNT ribs spaced RIB_PITCH apart, centred on pad
+        for (i = [0 : RIB_COUNT - 1]) {
+            rx = -PAD_W/2 + RIB_PITCH/2 + i * RIB_PITCH;
+            if (abs(rx) <= PAD_W/2 - RIB_W/2)   // stay within pad
+                translate([rx, 0, 0])
+                    cube([RIB_W, RIB_H, PAD_H - 4], center = true);
+        }
+
+        // ── Corner retention nubs (M2 boss for optional bolt-through) ────
+        for (px = [-PAD_W/2 + 5, PAD_W/2 - 5])
+        for (pz = [-PAD_H/2 + 5, PAD_H/2 - 5])
+            translate([px, -PAD_T/2, pz])
+                difference() {
+                    cylinder(d = 5, h = PAD_T, center = true);
+                    cylinder(d = M2_D, h = PAD_T + 2*e, center = true);
+                }
+    }
+}

chassis/prototype_baseplate.scad

@@ -65,7 +65,7 @@ CLAMP_ALIGN_D   =   4.1;   // Ø4 pin
 // D-cut bore clearance
 DCUT_CL         =  0.3;
 
-// FC mount — MAMBA F722S 30.5 × 30.5 mm M3
+// FC mount — ESP32-S3 BALANCE 30.5 × 30.5 mm M3
 FC_PITCH        = 30.5;
 FC_HOLE_D       =  3.2;
 // FC is offset toward front of plate (away from stem)
@@ -202,7 +202,7 @@ module base_plate() {
                 translate([STEM_FLANGE_BC/2, 0, -1])
                     cylinder(d=M5, h=PLATE_THICK + 2);
 
-        // ── FC mount (MAMBA F722S 30.5 × 30.5 M3) ────────────────────────
+        // ── FC mount (ESP32-S3 BALANCE 30.5 × 30.5 M3) ────────────────────────
         for (x = [FC_X_OFFSET - FC_PITCH/2, FC_X_OFFSET + FC_PITCH/2])
         for (y = [-FC_PITCH/2, FC_PITCH/2])
             translate([x, y, -1])

chassis/rover_electronics_bay.scad

@@ -11,7 +11,7 @@
 //          • Ventilation slots      — all 4 walls + lid
 //
 // Shared mounting patterns (swappable with SaltyLab):
-//   FC    : 30.5 × 30.5 mm M3 (MAMBA F722S / Pixhawk)
+//   FC    : 30.5 × 30.5 mm M3 (ESP32-S3 BALANCE / Pixhawk)
 //   Jetson: 58 × 49 mm M3    (Orin NX / Nano Devkit carrier)
 //
 // Coordinate: bay centred at origin; Z=0 = deck top face.

chassis/rplidar_mount.scad

@@ -1,76 +1,343 @@
 // ============================================================
-// rplidar_mount.scad — RPLIDAR A1M8 Anti-Vibration Ring  Rev A
+// RPLIDAR A1 Mount Bracket — Issue #596
-// Agent: sl-mechanical   2026-02-28
+// Agent   : sl-mechanical
-// ============================================================
+// Date    : 2026-03-14
-// Flat ring sits between platform and RPLIDAR A1M8.
+// Part catalogue:
-// Anti-vibration isolation via 4× M3 silicone grommets
+//   1. tnut_base     — 2020 T-slot rail interface plate with M5 T-nut captive pockets
-// (same type as FC vibration mounts — Ø6 mm silicone, M3).
+//   2. column        — hollow elevation column, 120 mm tall, 3 stiffening ribs, cable bore
+//   3. scan_platform — top plate with Ø40 mm BC M3 mounting pattern, vibration seats
+//   4. vibe_ring     — silicone FC-grommet isolation ring for scan_platform bolts
+//   5. cable_guide   — snap-on cable management clip for column body
 //
-// Bolt stack (bottom → top):
+// BOM:
-//   M3×30 SHCS → platform (8 mm) → grommet (8 mm) →
+//   2 × M5×10 BHCS + M5 T-nuts   (tnut_base to rail)
-//   ring (4 mm) → RPLIDAR bottom (threaded M3, ~6 mm engagement)
+//   4 × M3×8  SHCS                (scan_platform to RPLIDAR A1)
+//   4 × M3 silicone FC grommets Ø8.5 OD / Ø3.2 bore  (anti-vibe)
+//   4 × M3 hex nuts               (captured in scan_platform)
 //
-// RENDER options:
+// Print settings (PETG):
-//   "ring"       print-ready flat ring (default)
+//   tnut_base / column / scan_platform : 5 perimeters, 40 % gyroid, no supports
-//   "assembly"   ring in position on platform stub
+//   vibe_ring                          : 3 perimeters, 20 % gyroid, no supports
+//   cable_guide                        : 3 perimeters, 30 % gyroid, no supports
+//
+// Export commands:
+//   openscad -D 'RENDER="tnut_base"'     -o tnut_base.stl     rplidar_mount.scad
+//   openscad -D 'RENDER="column"'        -o column.stl        rplidar_mount.scad
+//   openscad -D 'RENDER="scan_platform"' -o scan_platform.stl rplidar_mount.scad
+//   openscad -D 'RENDER="vibe_ring"'     -o vibe_ring.stl     rplidar_mount.scad
+//   openscad -D 'RENDER="cable_guide"'   -o cable_guide.stl   rplidar_mount.scad
+//   openscad -D 'RENDER="assembly"'      -o assembly.png      rplidar_mount.scad
 // ============================================================
 
-RENDER = "ring";
+// ── Render selector ─────────────────────────────────────────
-
+RENDER = "assembly"; // tnut_base | column | scan_platform | vibe_ring | cable_guide | assembly
-// ── RPLIDAR A1M8 ─────────────────────────────────────────────
-RPL_BODY_D  = 70.0;          // body diameter
-RPL_BC      = 58.0;          // M3 mounting bolt circle
-
-// ── Mount ring ───────────────────────────────────────────────
-RING_OD     = 82.0;          // outer diameter (RPL_BODY_D + 12 mm)
-RING_ID     = 30.0;          // inner cutout (cable / airflow)
-RING_H      =  4.0;          // ring thickness
-
-BOLT_D      =  3.3;          // M3 clearance through-hole
-GROMMET_D   =  7.0;          // silicone grommet OD (seat recess on bottom)
-GROMMET_H   =  1.0;          // seating recess depth
 
+// ── Global constants ────────────────────────────────────────
 $fn = 64;
-e   = 0.01;
+EPS = 0.01;
 
-// ─────────────────────────────────────────────────────────────
+// 2020 rail
-module rplidar_ring() {
+RAIL_W       = 20.0;   // extrusion cross-section
-    difference() {
+RAIL_H       = 20.0;
-        cylinder(d = RING_OD, h = RING_H);
+SLOT_NECK_H  =  3.2;   // T-slot opening width
+TNUT_W       =  9.8;   // M5 T-nut width
+TNUT_H       =  5.5;   // T-nut height (depth into slot)
+TNUT_L       = 12.0;   // T-nut body length
+M5_D         =  5.2;   // M5 clearance bore
+M5_HEAD_D    =  9.5;   // M5 BHCS head diameter
+M5_HEAD_H    =  4.0;   // M5 BHCS head height
 
-        // Central cutout
+// Base plate
-        translate([0, 0, -e])
+BASE_L       = 60.0;   // length along rail axis
-            cylinder(d = RING_ID, h = RING_H + 2*e);
+BASE_W       = 30.0;   // width across rail
+BASE_T       =  8.0;   // plate thickness
+BOLT_PITCH   = 40.0;   // M5 bolt pitch along rail (centre-to-centre)
 
-        // 4× M3 clearance holes on bolt circle
+// Elevation column
-        for (a = [45, 135, 225, 315]) {
+COL_OD       = 25.0;   // column outer diameter
-            translate([RPL_BC/2 * cos(a), RPL_BC/2 * sin(a), -e])
+COL_ID       = 17.0;   // inner bore (cable routing)
-                cylinder(d = BOLT_D, h = RING_H + 2*e);
+ELEV_H       = 120.0;  // scan plane above rail top face
-        }
+COL_WALL     = (COL_OD - COL_ID) / 2;
+RIB_W        =  3.0;   // stiffening rib width
+RIB_H        =  3.5;   // rib radial height
+CABLE_SLOT_W =  8.0;   // cable entry slot width
+CABLE_SLOT_H =  5.0;   // cable entry slot height
 
-        // Grommet seating recesses — bottom face
+// Scan platform
-        for (a = [45, 135, 225, 315]) {
+PLAT_D       = 60.0;   // platform disc diameter (clears RPLIDAR body Ø100 mm well)
-            translate([RPL_BC/2 * cos(a), RPL_BC/2 * sin(a), -e])
+PLAT_T       =  6.0;   // platform thickness
-                cylinder(d = GROMMET_D, h = GROMMET_H + e);
+RPL_BC_D     = 40.0;   // RPLIDAR M3 bolt circle diameter (4 bolts at 45 °)
-        }
+RPL_BORE_D   = 36.0;   // central pass-through for scan motor cable
+M3_D         =  3.2;   // M3 clearance bore
+M3_NUT_W     =  5.5;   // M3 hex nut across-flats
+M3_NUT_H     =  2.4;   // M3 hex nut height
+GROM_OD      =  8.5;   // FC silicone grommet OD
+GROM_ID      =  3.2;   // grommet bore
+GROM_H       =  3.0;   // grommet seat depth
+CONN_SLOT_W  = 12.0;   // connector side-exit slot width
+CONN_SLOT_H  =  5.0;   // connector slot height
+
+// Vibe ring
+VRING_OD     = GROM_OD + 1.6;  // printed retainer OD
+VRING_ID     = GROM_ID + 0.3;  // pass-through with grommet seated
+VRING_T      =  2.0;            // ring flange thickness
+
+// Cable guide clip
+CLIP_W       = 14.0;
+CLIP_T       =  3.5;
+CLIP_GAP     = COL_OD + 0.4;   // snap-fit gap (slight interference)
+SNAP_T       =  1.8;
+CABLE_CH_W   =  8.0;
+CABLE_CH_H   =  5.0;
+
+// ── Utility modules ─────────────────────────────────────────
+module chamfer_cube(size, ch=1.0) {
+    // simple chamfered box (bottom edge only for printability)
+    hull() {
+        translate([ch, ch, 0])
+            cube([size[0]-2*ch, size[1]-2*ch, EPS]);
+        translate([0, 0, ch])
+            cube(size - [0, 0, ch]);
     }
 }
 
-// ─────────────────────────────────────────────────────────────
+module hex_pocket(af, depth) {
-// Render selector
+    // hex nut pocket (flat-to-flat af)
-// ─────────────────────────────────────────────────────────────
+    cylinder(d = af / cos(30), h = depth, $fn = 6);
-if (RENDER == "ring") {
-    rplidar_ring();
-
-} else if (RENDER == "assembly") {
-    // Platform stub
-    color("Silver", 0.5)
-        difference() {
-            cylinder(d = 90, h = 8);
-            translate([0, 0, -e]) cylinder(d = 25.4, h = 8 + 2*e);
-        }
-    // Ring floating 8 mm above (grommet gap)
-    color("SkyBlue", 0.9)
-        translate([0, 0, 8 + 8])
-            rplidar_ring();
 }
+
+// ── Part 1: tnut_base ───────────────────────────────────────
+module tnut_base() {
+    difference() {
+        // Body
+        union() {
+            chamfer_cube([BASE_L, BASE_W, BASE_T], ch=1.5);
+            // Column socket boss centred on plate top face
+            translate([BASE_L/2, BASE_W/2, BASE_T])
+                cylinder(d=COL_OD + 4.0, h=8.0);
+        }
+
+        // M5 bolt holes (counterbored for BHCS heads from underneath)
+        for (x = [BASE_L/2 - BOLT_PITCH/2, BASE_L/2 + BOLT_PITCH/2])
+            translate([x, BASE_W/2, -EPS]) {
+                cylinder(d=M5_D, h=BASE_T + 8.0 + 2*EPS);
+                // counterbore from bottom
+                cylinder(d=M5_HEAD_D, h=M5_HEAD_H + EPS);
+            }
+
+        // T-nut captive pockets (accessible from bottom)
+        for (x = [BASE_L/2 - BOLT_PITCH/2, BASE_L/2 + BOLT_PITCH/2])
+            translate([x - TNUT_L/2, BASE_W/2 - TNUT_W/2, BASE_T - TNUT_H])
+                cube([TNUT_L, TNUT_W, TNUT_H + EPS]);
+
+        // Column bore into boss
+        translate([BASE_L/2, BASE_W/2, BASE_T - EPS])
+            cylinder(d=COL_OD + 0.3, h=8.0 + 2*EPS);
+
+        // Cable exit slot through base (offset 5 mm from column centre)
+        translate([BASE_L/2 - CABLE_SLOT_W/2, BASE_W/2 + COL_OD/4, -EPS])
+            cube([CABLE_SLOT_W, CABLE_SLOT_H, BASE_T + 8.0 + 2*EPS]);
+
+        // Weight relief pockets on underside
+        for (x = [BASE_L/2 - BOLT_PITCH/2 + 10, BASE_L/2 + BOLT_PITCH/2 - 10])
+            for (y = [7, BASE_W - 7])
+                translate([x - 5, y - 5, -EPS])
+                    cube([10, 10, BASE_T/2]);
+    }
+}
+
+// ── Part 2: column ──────────────────────────────────────────
+module column() {
+    // Actual column height: ELEV_H minus base boss engagement (8 mm) and platform seating (6 mm)
+    col_h = ELEV_H - 8.0 - PLAT_T;
+
+    difference() {
+        union() {
+            // Hollow tube
+            cylinder(d=COL_OD, h=col_h);
+
+            // Three 120°-spaced stiffening ribs along full height
+            for (a = [0, 120, 240])
+                rotate([0, 0, a])
+                    translate([COL_OD/2 - EPS, -RIB_W/2, 0])
+                        cube([RIB_H, RIB_W, col_h]);
+
+            // Bottom spigot (fits into base boss bore)
+            translate([0, 0, -6.0])
+                cylinder(d=COL_OD - 0.4, h=6.0 + EPS);
+
+            // Top spigot (seats into scan_platform recess)
+            translate([0, 0, col_h - EPS])
+                cylinder(d=COL_OD - 0.4, h=6.0);
+        }
+
+        // Inner cable bore
+        translate([0, 0, -6.0 - EPS])
+            cylinder(d=COL_ID, h=col_h + 12.0 + 2*EPS);
+
+        // Cable entry slot at bottom (aligns with base slot)
+        translate([-CABLE_SLOT_W/2, -COL_OD/2 - EPS, 2.0])
+            cube([CABLE_SLOT_W, CABLE_SLOT_H + EPS, CABLE_SLOT_H]);
+
+        // Cable exit slot at top (90° rotated for tidy routing)
+        rotate([0, 0, 90])
+            translate([-CABLE_SLOT_W/2, -COL_OD/2 - EPS, col_h - CABLE_SLOT_H - 4.0])
+                cube([CABLE_SLOT_W, CABLE_SLOT_H + EPS, CABLE_SLOT_H]);
+
+        // Cable clip snap groove (at mid-height)
+        translate([0, 0, col_h / 2])
+            difference() {
+                cylinder(d=COL_OD + 2*RIB_H + 0.8, h=4.0, center=true);
+                cylinder(d=COL_OD - 0.2, h=4.0 + 2*EPS, center=true);
+            }
+    }
+}
+
+// ── Part 3: scan_platform ───────────────────────────────────
+module scan_platform() {
+    difference() {
+        union() {
+            // Main disc
+            cylinder(d=PLAT_D, h=PLAT_T);
+
+            // Rim lip for stiffness
+            translate([0, 0, PLAT_T])
+                difference() {
+                    cylinder(d=PLAT_D, h=2.0);
+                    cylinder(d=PLAT_D - 4.0, h=2.0 + EPS);
+                }
+        }
+
+        // Central cable pass-through
+        translate([0, 0, -EPS])
+            cylinder(d=RPL_BORE_D, h=PLAT_T + 4.0);
+
+        // Column spigot socket (bottom recess)
+        translate([0, 0, -EPS])
+            cylinder(d=COL_OD - 0.4 + 0.4, h=6.0);
+
+        // RPLIDAR M3 mounting holes — 4× on Ø40 BC at 45°/135°/225°/315°
+        for (a = [45, 135, 225, 315])
+            rotate([0, 0, a])
+                translate([RPL_BC_D/2, 0, -EPS]) {
+                    // Through bore
+                    cylinder(d=M3_D, h=PLAT_T + 2*EPS);
+                    // Grommet seat (countersunk from top)
+                    translate([0, 0, PLAT_T - GROM_H])
+                        cylinder(d=GROM_OD + 0.3, h=GROM_H + EPS);
+                    // Captured M3 hex nut pocket (from bottom)
+                    translate([0, 0, 1.5])
+                        hex_pocket(M3_NUT_W + 0.3, M3_NUT_H + 0.2);
+                }
+
+        // Connector side-exit slots (2× opposing, at 0° and 180°)
+        for (a = [0, 180])
+            rotate([0, 0, a])
+                translate([-CONN_SLOT_W/2, PLAT_D/2 - CONN_SLOT_H, -EPS])
+                    cube([CONN_SLOT_W, CONN_SLOT_H + EPS, PLAT_T + 2*EPS]);
+
+        // Weight relief pockets (2× lateral)
+        for (a = [90, 270])
+            rotate([0, 0, a])
+                translate([-10, 15, 1.5])
+                    cube([20, 8, PLAT_T - 3.0]);
+    }
+}
+
+// ── Part 4: vibe_ring ───────────────────────────────────────
+// Printed silicone-grommet retainer ring — press-fits over M3 bolt with grommet seated
+module vibe_ring() {
+    difference() {
+        union() {
+            cylinder(d=VRING_OD, h=VRING_T + GROM_H);
+            // Flange
+            cylinder(d=VRING_OD + 2.0, h=VRING_T);
+        }
+        // Bore
+        translate([0, 0, -EPS])
+            cylinder(d=VRING_ID, h=VRING_T + GROM_H + 2*EPS);
+    }
+}
+
+// ── Part 5: cable_guide ─────────────────────────────────────
+// Snap-on cable clip for column mid-section
+module cable_guide() {
+    arm_t = SNAP_T;
+    gap   = CLIP_GAP;
+
+    difference() {
+        union() {
+            // Saddle body (U-shape wrapping column)
+            difference() {
+                cylinder(d=gap + 2*CLIP_T, h=CLIP_W);
+                translate([0, 0, -EPS])
+                    cylinder(d=gap, h=CLIP_W + 2*EPS);
+                // Open front slot for snap insertion
+                translate([-gap/2, 0, -EPS])
+                    cube([gap, gap/2 + CLIP_T + EPS, CLIP_W + 2*EPS]);
+            }
+
+            // Snap arms
+            for (s = [-1, 1])
+                translate([s*(gap/2 - arm_t), 0, 0])
+                    mirror([s < 0 ? 1 : 0, 0, 0])
+                        translate([0, -arm_t/2, 0])
+                            cube([arm_t + 1.5, arm_t, CLIP_W]);
+
+            // Cable channel bracket (side-mounted)
+            translate([gap/2 + CLIP_T, -(CABLE_CH_W/2 + CLIP_T), 0])
+                cube([CLIP_T + CABLE_CH_H, CABLE_CH_W + 2*CLIP_T, CLIP_W]);
+        }
+
+        // Cable channel cutout
+        translate([gap/2 + CLIP_T + CLIP_T - EPS, -CABLE_CH_W/2, -EPS])
+            cube([CABLE_CH_H + EPS, CABLE_CH_W, CLIP_W + 2*EPS]);
+
+        // Snap tip undercut (both arms)
+        for (s = [-1, 1])
+            translate([s*(gap/2 + CLIP_T + 1.0), -arm_t, -EPS])
+                rotate([0, 0, s*30])
+                    cube([2, arm_t*2, CLIP_W + 2*EPS]);
+    }
+}
+
+// ── Assembly / render dispatch ───────────────────────────────
+module assembly() {
+    // tnut_base at origin
+    color("SteelBlue")
+        tnut_base();
+
+    // column rising from base boss
+    color("DodgerBlue")
+        translate([BASE_L/2, BASE_W/2, BASE_T + 8.0 - 6.0])
+            column();
+
+    // scan_platform at top of column
+    col_h_actual = ELEV_H - 8.0 - PLAT_T;
+    color("CornflowerBlue")
+        translate([BASE_L/2, BASE_W/2, BASE_T + 8.0 - 6.0 + col_h_actual + 6.0 - EPS])
+            scan_platform();
+
+    // vibe rings (4×) seated in platform holes
+    for (a = [45, 135, 225, 315])
+        color("Gray", 0.7)
+            translate([BASE_L/2, BASE_W/2,
+                       BASE_T + 8.0 - 6.0 + col_h_actual + 6.0 + PLAT_T - GROM_H])
+                rotate([0, 0, a])
+                    translate([RPL_BC_D/2, 0, 0])
+                        vibe_ring();
+
+    // cable_guide clipped at column mid-height
+    color("LightSteelBlue")
+        translate([BASE_L/2, BASE_W/2,
+                   BASE_T + 8.0 - 6.0 + (ELEV_H - 8.0 - PLAT_T)/2 - CLIP_W/2])
+            cable_guide();
+}
+
+// ── Dispatch ────────────────────────────────────────────────
+if      (RENDER == "tnut_base")     tnut_base();
+else if (RENDER == "column")        column();
+else if (RENDER == "scan_platform") scan_platform();
+else if (RENDER == "vibe_ring")     vibe_ring();
+else if (RENDER == "cable_guide")   cable_guide();
+else                                assembly();

chassis/saltyrover_chassis_r2.scad

@@ -17,7 +17,7 @@
 //   • Weight target: <2 kg frame (excl. motors/electronics)
 //
 // Shared SaltyLab patterns (swappable electronics):
-//   FC  : 30.5 × 30.5 mm M3  (MAMBA F722S / Pixhawk)
+//   FC  : 30.5 × 30.5 mm M3  (ESP32-S3 BALANCE / Pixhawk)
 //   Jetson: 58 × 49 mm M3    (Orin NX / Nano carrier board)
 //   Stem  : Ø25 mm bore      (sensor head unchanged)
 //
@@ -87,7 +87,7 @@ STEM_COLLAR_OD = 50.0;
 STEM_COLLAR_H  = 20.0;   // raised boss height above deck top
 STEM_FLANGE_BC = 40.0;   // 4× M4 bolt circle for stem adapter
 
-// ── FC mount — MAMBA F722S / Pixhawk (30.5 × 30.5 mm M3) ────────────────────
+// ── FC mount — ESP32-S3 BALANCE / Pixhawk (30.5 × 30.5 mm M3) ────────────────────
 // Shared with SaltyLab — swappable electronics
 FC_PITCH    = 30.5;
 FC_HOLE_D   =  3.2;