sl-mechanical
796e343b78
Dovetail rail + tool-free swappable payload modules for all variants: - payload_bay_rail.scad: 50×12 mm 60° dovetail rail (DXF for CNC Al bar), spring ball detent (Ø6 mm, 50 mm pitch), continuous safety-lock groove (M4 thumbscrew), 4-pin pogo connector housing (GND/5V/12V/UART), lab/rover/tank deck adapter plates - payload_bay_modules.scad: universal _module_base() (male tongue, detent bore, 4× Ø4 mm target pads, lock bore) + 3 example modules: cargo tray (200×100 mm, Velcro slots, bungee cord slots), camera boom (120 mm mast + 80 mm arm, 2020-rail-compatible head, 3-position tilt), cup holder (Ø80 mm tapered, 8-slot flex grip). Includes copy-paste module template. - payload_bay_BOM.md: hardware list, CNC spec (dovetail dimensions, surface finish, connector pocket), load analysis (2 kg rated with Al rail + lock), module developer guide with constraints table Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
430 lines
19 KiB
OpenSCAD
430 lines
19 KiB
OpenSCAD
// ============================================================
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// payload_bay_rail.scad — Modular Payload Bay Rail System
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// Issue: #170 Agent: sl-mechanical Date: 2026-03-01
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// ============================================================
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//
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// Dovetail rail mounted on robot top deck. Payload modules slide on
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// from either end and are retained by a spring-loaded ball detent plus
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// an optional M4 thumbscrew safety lock.
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//
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// Dovetail geometry (60° included angle — balanced for print + load):
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//
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// ← RAIL_W (50 mm) →
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// ┌──────────────────┐ ← rail top face (Z = RAIL_T)
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// │ ╲ ╱ │
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// │ ╲__________╱ │ ← dovetail slot (female, cut into top)
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// │ (DOVE_SLOT) │
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// └──────────────────┘ ← rail bottom face (Z = 0)
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//
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// DOVE_ANGLE = 30° from vertical (= 60° included).
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// Slot width at top = DOVE_SLOT_TOP (open face)
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// Slot width at bottom = DOVE_SLOT_BOT (inner base of slot)
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// Slot depth = DOVE_H
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//
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// Module tongue (male dovetail) slides in with 0.3 mm clearance each side.
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//
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// Spring detent: Ø6 mm steel ball in module, spring behind, seats in
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// Ø4.9 mm dimples drilled into rail slot bottom at DETENT_PITCH spacing.
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// Provides tactile click-lock at each indexed position.
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//
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// Safety lock: M4 thumbscrew through module side, tightens against rail
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// side wall. For vibration environments or >1 kg payload.
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//
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// Power+data connector: 4-pin pogo array in rail at fixed position.
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// Pins: GND | +5 V | +12 V | UART (half-duplex)
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// Module has matching brass target pads (Ø4 mm).
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// Connector position: centred in rail length, at CONN_Y from one end.
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//
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// Cross-variant adapter plates (this file):
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// lab_rail_adapter() — SaltyLab chassis top (Ø25 mm stem clear)
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// rover_rail_adapter() — SaltyRover deck (M4 grid)
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// tank_rail_adapter() — SaltyTank deck (M4 grid)
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//
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// Coordinate convention:
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// Rail runs along Y axis. Cross-section in X-Z plane.
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// Z = 0 at rail bottom face (= robot deck top face).
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// Module slides in +Y direction.
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//
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// RENDER options:
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// "assembly" rail + adapter + module ghost
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// "rail_2d" DXF — dovetail cross-section (CNC/waterjet)
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// "rail_stl" STL — printable rail section (PETG prototype)
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// "connector_stl" STL — pogo connector housing insert
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// "detent_plunger_stl" STL — spring detent plunger (print ×2 per module)
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// "lab_adapter_stl" STL — SaltyLab deck adapter
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// "rover_adapter_stl" STL — SaltyRover deck adapter
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// "tank_adapter_stl" STL — SaltyTank deck adapter
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//
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// Export:
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// openscad payload_bay_rail.scad -D 'RENDER="rail_2d"' -o payload_rail.dxf
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// openscad payload_bay_rail.scad -D 'RENDER="rail_stl"' -o payload_rail.stl
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// openscad payload_bay_rail.scad -D 'RENDER="connector_stl"' -o payload_connector.stl
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// openscad payload_bay_rail.scad -D 'RENDER="detent_plunger_stl"' -o payload_detent.stl
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// openscad payload_bay_rail.scad -D 'RENDER="lab_adapter_stl"' -o payload_lab_adapter.stl
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// openscad payload_bay_rail.scad -D 'RENDER="rover_adapter_stl"' -o payload_rover_adapter.stl
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// openscad payload_bay_rail.scad -D 'RENDER="tank_adapter_stl"' -o payload_tank_adapter.stl
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// ============================================================
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$fn = 64;
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e = 0.01;
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// ── Dovetail rail cross-section ───────────────────────────────────────────────
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RAIL_W = 50.0; // rail total width (X)
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RAIL_T = 12.0; // rail total height (Z)
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RAIL_R = 2.0; // outer corner radius
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RAIL_LEN = 200.0; // default rail section length (Y)
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// Dovetail slot geometry
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DOVE_ANGLE = 30.0; // degrees from vertical (60° included angle)
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DOVE_H = 8.0; // slot depth (Z into rail from top)
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DOVE_SLOT_BOT= 28.0; // slot width at bottom (inner)
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// Derived: slot width at top = DOVE_SLOT_BOT + 2 * DOVE_H * tan(DOVE_ANGLE)
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DOVE_SLOT_TOP= DOVE_SLOT_BOT + 2 * DOVE_H * tan(DOVE_ANGLE); // ≈ 37.2 mm
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// Module tongue (male) clearance: 0.3 mm per side
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DOVE_CLEAR = 0.3;
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// → module tongue: bot_w = DOVE_SLOT_BOT - 2*DOVE_CLEAR, top_w = DOVE_SLOT_TOP + 2*DOVE_CLEAR
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// ── Spring ball detent ────────────────────────────────────────────────────────
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// Ø6 mm steel ball presses up through module tongue into dimples in rail slot.
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DETENT_BALL_D = 6.0; // ball diameter
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DETENT_HOLE_D = 4.9; // dimple bore in rail slot bottom (ball seats in)
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DETENT_DEPTH = 1.5; // dimple depth (ball sinks in this far)
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DETENT_PITCH = 50.0; // dimple spacing along rail (Y) — module index positions
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DETENT_SPG_OD = 6.2; // plunger bore OD (ball + spring housing in module)
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DETENT_SPG_L = 16.0; // spring pocket depth in module tongue
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// ── Safety lock (M4 thumbscrew through module side into rail side groove) ─────
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LOCK_GROOVE_D = 4.5; // groove in rail side wall (M4 thumbscrew tip seats in)
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LOCK_GROOVE_DEPTH = 1.5; // groove depth into rail side
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// Lock groove runs full rail length (continuous slot) for tool-free slide + lock anywhere
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// ── 4-pin power+data connector ───────────────────────────────────────────────
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// Pogo pin array mounted in rail body at CONN_Y from entry end.
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// Pin map: 1=GND 2=+5V 3=+12V 4=UART
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// Pogo: Ø2 mm spring contact (P75-E2 style), rated 2 A (power), 0.5 A (signal)
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CONN_Y = RAIL_LEN / 2; // connector centred in rail section
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CONN_PIN_D = 2.2; // pogo bore (2 mm pin + 0.2 mm clearance)
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CONN_PIN_SPC = 5.0; // pin centre-to-centre spacing
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CONN_N_PINS = 4; // GND / +5V / +12V / UART
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CONN_HOUSING_W= CONN_N_PINS * CONN_PIN_SPC + 4; // housing width (X)
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CONN_HOUSING_D= 8.0; // housing depth (Y, inside rail)
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CONN_HOUSING_H= DOVE_H - 1.0; // housing height; sits inside slot (flush with slot floor)
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// Connector pogo pins point upward into module pad targets.
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// ── Deck mounting holes ───────────────────────────────────────────────────────
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MOUNT_PITCH = 50.0; // M4 FHCS hole pitch along rail (countersunk from bottom)
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MOUNT_INSET = 25.0; // first hole Y from rail end
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MOUNT_D = 4.3; // M4 clearance
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CSINK_D = 8.0; // M4 FHCS head diameter
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// ── Cross-variant adapter plates ─────────────────────────────────────────────
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ADAPT_T = 4.0; // adapter plate thickness
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ADAPT_OVHG = 10.0; // adapter overhang past rail edge each side (flange width)
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// SaltyLab deck: stem bore at centre
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LAB_STEM_BORE = 26.0; // clear stem Ø25 mm
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// SaltyRover deck: M4 bolt grid (spacing from rover_chassis_r2.scad)
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ROVER_BOLT_SPC = 40.0;
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// SaltyTank deck: M4 bolt grid (spacing from saltytank_chassis.scad)
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TANK_BOLT_SPC = 40.0;
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// Fasteners
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M3_D = 3.3;
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M4_D = 4.3;
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// ============================================================
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// RENDER DISPATCH
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// ============================================================
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RENDER = "assembly";
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if (RENDER == "assembly") assembly();
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else if (RENDER == "rail_2d")
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projection(cut = true) translate([0, 0, -0.5])
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linear_extrude(1) rail_profile_2d();
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else if (RENDER == "rail_stl") rail_section(RAIL_LEN);
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else if (RENDER == "connector_stl") connector_housing();
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else if (RENDER == "detent_plunger_stl") detent_plunger();
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else if (RENDER == "lab_adapter_stl") lab_rail_adapter();
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else if (RENDER == "rover_adapter_stl") rover_rail_adapter();
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else if (RENDER == "tank_adapter_stl") tank_rail_adapter();
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// ============================================================
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// ASSEMBLY PREVIEW
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// ============================================================
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module assembly() {
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// Rail section
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color("Silver", 0.85) rail_section(RAIL_LEN);
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// Rover adapter under rail
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color("SteelBlue", 0.70)
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translate([0, 0, -ADAPT_T])
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rover_rail_adapter();
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// Ghost module sliding on
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%color("OliveDrab", 0.3)
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translate([0, 60, RAIL_T])
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cube([RAIL_W + 10, 100, 40], center = true);
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// Connector position marker
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%color("Gold", 0.5)
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translate([0, CONN_Y, RAIL_T - DOVE_H])
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cube([CONN_HOUSING_W, CONN_HOUSING_D, CONN_HOUSING_H],
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center = true);
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// Detent dimple markers
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for (dy = [MOUNT_INSET : DETENT_PITCH : RAIL_LEN - MOUNT_INSET])
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%color("Red", 0.6)
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translate([0, dy, RAIL_T - DOVE_H])
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cylinder(d = DETENT_HOLE_D, h = DETENT_DEPTH);
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}
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// ============================================================
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// RAIL CROSS-SECTION 2D (DXF export)
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// ============================================================
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// Outer profile minus dovetail slot.
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// For CNC milling from 50×12 mm aluminium bar, or waterjet from plate.
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// Also used for PETG prototype extrusion.
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module rail_profile_2d() {
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difference() {
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// Outer rail cross-section (rounded rect)
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minkowski() {
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square([RAIL_W - 2*RAIL_R, RAIL_T - 2*RAIL_R],
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center = true);
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circle(r = RAIL_R);
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}
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// Dovetail slot (trapezoid, open at top)
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translate([0, RAIL_T/2])
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_dovetail_slot_2d();
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}
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}
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// ── Dovetail slot 2D (trapezoid with open top) ───────────────────────────────
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module _dovetail_slot_2d() {
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// Trapezoid: wider at top (open face), narrower at bottom.
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// Points listed clockwise from top-left:
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polygon([
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[-DOVE_SLOT_TOP/2, 0], // top-left
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[ DOVE_SLOT_TOP/2, 0], // top-right
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[ DOVE_SLOT_BOT/2, -DOVE_H], // bottom-right
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[-DOVE_SLOT_BOT/2, -DOVE_H], // bottom-left
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]);
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}
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// ── Dovetail slot for difference() operations (3D volume) ────────────────────
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module _dovetail_slot_3d(length) {
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translate([0, -e, RAIL_T])
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linear_extrude(DOVE_H + e)
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offset(delta = e)
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_dovetail_slot_2d();
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}
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// ============================================================
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// RAIL SECTION (3D — printable or aluminium)
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// ============================================================
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module rail_section(len = RAIL_LEN) {
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difference() {
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// ── Extruded profile ────────────────────────────────────────
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linear_extrude(len)
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rotate([0, 0, 90])
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rail_profile_2d();
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// ── Dovetail slot ────────────────────────────────────────────
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translate([0, -e, RAIL_T])
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rotate([0, 0, 0])
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linear_extrude(len + 2*e)
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rotate([0, 0, 90])
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offset(delta = e)
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_dovetail_slot_2d();
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// ── Deck mounting holes (M4 FHCS, from bottom) ───────────────
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for (my = [MOUNT_INSET : MOUNT_PITCH : len - MOUNT_INSET])
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translate([0, my, -e])
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cylinder(d = MOUNT_D, h = RAIL_T - DOVE_H + 2*e);
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// Countersinks on bottom face
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for (my = [MOUNT_INSET : MOUNT_PITCH : len - MOUNT_INSET])
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translate([0, my, -e])
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cylinder(d1 = CSINK_D, d2 = MOUNT_D,
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h = (CSINK_D - MOUNT_D) / (2 * tan(41)));
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// ── Spring detent dimples (slot bottom, at DETENT_PITCH) ──────
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for (dy = [MOUNT_INSET : DETENT_PITCH : len - MOUNT_INSET])
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translate([0, dy, RAIL_T - DOVE_H - e])
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cylinder(d = DETENT_HOLE_D, h = DETENT_DEPTH + e);
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// ── Safety-lock groove (continuous slot, both sides of rail) ──
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// M4 thumbscrew tip seats anywhere along groove
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for (sx = [-1, 1])
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translate([sx * (RAIL_W/2 + e), -e,
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RAIL_T - DOVE_H/2])
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rotate([0, 90, 0])
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hull() {
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translate([0, 0, 0])
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cylinder(d = LOCK_GROOVE_D, h = RAIL_W + 2*e);
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}
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// ── Connector housing pocket (at CONN_Y) ──────────────────────
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translate([0, CONN_Y, RAIL_T - DOVE_H - e])
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cube([CONN_HOUSING_W + 0.4,
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CONN_HOUSING_D + 0.4,
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CONN_HOUSING_H + e], center = true);
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// ── Lightening slots (rail body between mounting holes) ────────
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for (my = [MOUNT_INSET + 25 : MOUNT_PITCH : len - MOUNT_INSET - 25])
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translate([0, my, RAIL_T/4])
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cube([RAIL_W - 16, 20, RAIL_T/2 + 2*e], center = true);
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}
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}
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// ============================================================
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// CONNECTOR HOUSING (pogo-pin insert, press-fits into rail pocket)
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// ============================================================
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// 4× spring-loaded pogo pins (P75-E2, Ø2 mm, 6 mm travel).
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// Printed housing press-fits into rail pocket; pins protrude up into module.
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// Module has 4× Ø4 mm brass target pads at matching pitch.
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//
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// Pin map (left to right, looking at rail top from +Z):
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// Pin 1: GND Pin 2: +5 V Pin 3: +12 V Pin 4: UART
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module connector_housing() {
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hw = CONN_HOUSING_W;
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hd = CONN_HOUSING_D;
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hh = CONN_HOUSING_H;
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difference() {
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// Housing body (press-fit into rail pocket)
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cube([hw, hd, hh], center = true);
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// 4× pogo pin bores (through housing, top to bottom)
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for (i = [0 : CONN_N_PINS - 1]) {
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px = (i - (CONN_N_PINS - 1) / 2) * CONN_PIN_SPC;
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translate([px, 0, -hh/2 - e])
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cylinder(d = CONN_PIN_D, h = hh + 2*e);
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}
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// Wire exit slot (bottom, routes into rail body)
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translate([0, 0, -hh/2 - e])
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cube([hw - 6, hd/2, hh/3 + e], center = true);
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// Retention barbs (prevent housing pulling out of pocket)
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for (sx = [-1, 1])
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translate([sx * (hw/2 - 1), 0, hh/4])
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rotate([0, sx * 15, 0])
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cube([2, hd + 2*e, 2.5], center = true);
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}
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// Pin polarity label recess (on top face, GND side)
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difference() {
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translate([0, 0, 0]) cube([0, 0, 0]); // null
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translate([-(CONN_N_PINS * CONN_PIN_SPC)/2 + 1, 0, hh/2 - 0.4])
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cube([3, hd * 0.6, 0.5 + e], center = true);
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}
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}
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// ============================================================
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// DETENT PLUNGER (lives in module tongue; print 2× per module)
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// ============================================================
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// Press-fit into Ø6.2 mm bore in module tongue.
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// Includes spring pocket; ball seated on top.
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// Spring: Ø5.5 mm OD, 12 mm free length, ~2 N/mm (light detent).
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// Ball: Ø6 mm steel (standard bearing ball, purchase).
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module detent_plunger() {
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bore_d = DETENT_BALL_D + 0.2; // 6.2 mm
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body_od = DETENT_SPG_OD;
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body_len = DETENT_SPG_L;
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spg_d = 5.8; // spring OD
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spg_pocket = 10.0; // spring pocket depth (bottom of housing)
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difference() {
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cylinder(d = body_od, h = body_len);
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// Ball socket (top — partial sphere, retains ball)
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translate([0, 0, body_len])
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sphere(d = bore_d);
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translate([0, 0, body_len - bore_d/4])
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cylinder(d = bore_d, h = bore_d/2 + e);
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// Spring pocket (bottom)
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translate([0, 0, -e])
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cylinder(d = spg_d + 0.3, h = spg_pocket + e);
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// Retention lip (allows push-in but prevents pullout before spring seated)
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translate([0, 0, spg_pocket])
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cylinder(d1 = spg_d + 0.3, d2 = spg_d - 1,
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h = 1.5);
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}
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}
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// ============================================================
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// CROSS-VARIANT DECK ADAPTER PLATES
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// ============================================================
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// Thin plates that bolt to the robot deck and provide M4 threaded
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// studs (or through holes) for the rail mounting holes.
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// All adapters: RAIL_LEN × (RAIL_W + 2×ADAPT_OVHG) footprint.
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module _adapter_base() {
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adapt_l = RAIL_LEN;
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adapt_w = RAIL_W + 2*ADAPT_OVHG;
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difference() {
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// Plate
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cube([adapt_w, adapt_l, ADAPT_T], center = true);
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// Rail mounting holes (M4 FHCS up through adapter into rail bottom)
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for (my = [MOUNT_INSET : MOUNT_PITCH : adapt_l - MOUNT_INSET])
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translate([0, my - adapt_l/2, -ADAPT_T/2 - e])
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cylinder(d = MOUNT_D, h = ADAPT_T + 2*e);
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// Corner lightening
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for (cx = [-1, 1]) for (cy = [-1, 1])
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translate([cx * (adapt_w/2 - 12),
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cy * (adapt_l/2 - 20), 0])
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cylinder(d = 10, h = ADAPT_T + 2*e, center = true);
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}
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}
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// SaltyLab adapter: clears Ø25 mm stem, 4× M4 to lab chassis ring
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module lab_rail_adapter() {
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difference() {
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_adapter_base();
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// Stem bore clearance (at centre of adapter)
|
||
cylinder(d = LAB_STEM_BORE, h = ADAPT_T + 2*e, center = true);
|
||
// 4× M4 mounting to lab chassis top ring (Ø44 mm bolt circle)
|
||
for (a = [45, 135, 225, 315])
|
||
translate([22*cos(a), 22*sin(a), -ADAPT_T/2 - e])
|
||
cylinder(d = M4_D, h = ADAPT_T + 2*e);
|
||
}
|
||
}
|
||
|
||
// SaltyRover adapter: 4× M4 to rover deck bolt grid
|
||
module rover_rail_adapter() {
|
||
adapt_l = RAIL_LEN;
|
||
adapt_w = RAIL_W + 2*ADAPT_OVHG;
|
||
difference() {
|
||
_adapter_base();
|
||
// 2 rows × 3 cols of M4 bolts into rover deck
|
||
for (rx = [-ROVER_BOLT_SPC/2, ROVER_BOLT_SPC/2])
|
||
for (ry = [-adapt_l/3, 0, adapt_l/3])
|
||
translate([rx, ry, -ADAPT_T/2 - e])
|
||
cylinder(d = M4_D, h = ADAPT_T + 2*e);
|
||
}
|
||
}
|
||
|
||
// SaltyTank adapter: M4 to tank deck; relieved for deck cable slots
|
||
module tank_rail_adapter() {
|
||
adapt_l = RAIL_LEN;
|
||
adapt_w = RAIL_W + 2*ADAPT_OVHG;
|
||
difference() {
|
||
_adapter_base();
|
||
// 2 rows × 3 cols of M4 bolts into tank deck
|
||
for (rx = [-TANK_BOLT_SPC/2, TANK_BOLT_SPC/2])
|
||
for (ry = [-adapt_l/3, 0, adapt_l/3])
|
||
translate([rx, ry, -ADAPT_T/2 - e])
|
||
cylinder(d = M4_D, h = ADAPT_T + 2*e);
|
||
// Deck cable slot clearance (tank deck has centre cable channel)
|
||
translate([0, 0, 0])
|
||
cube([10, adapt_l - 40, ADAPT_T + 2*e], center = true);
|
||
}
|
||
}
|