sl-mechanical
22d7b546f3
Adds prototype_baseplate.scad — a laser-cuttable / CNC-routable flat base plate for the self-balancing robot using caliper-verified axle dimensions from the wiki (replaces placeholder values in PR #7): Axle base dia: 16.11 mm (was 14 mm) D-cut OD: 15.95 mm (new) D-cut flat chord: 13.00 mm (new) Total protrusion: 65.50 mm Bearing seat OD: 37.80 mm Tire OD: 254 mm (10x2.125") Axle CL height: 127 mm (was wrong 310 mm) Design: - Single flat plate (6 mm Al / 8 mm acrylic), 680x220 mm blank - Open fork slots (16.51 mm, semicircular tip) at each axle end - Bearing seat relief cutout prevents Ø37.8 mm collar binding on edge - Two-piece dropout clamp: lower (round bore) + upper (D-cut bore) - D-cut profile computed from chord geometry with 0.3 mm all-round clearance - MAMBA F722S FC holes (30.5x30.5 mm M3), battery mount holes (M4) - Lightening slots, corner radii via minkowski - RENDER param switches between 3-D assembly and 2-D DXF projections for each of the three laser-cut parts Updates BOM.md to Rev B: measurement delta table, prototype BOM section, updated motor entry with verified axle spec. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
372 lines
16 KiB
OpenSCAD
372 lines
16 KiB
OpenSCAD
// =============================================================================
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// SaltyBot — Prototype Base Plate
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// Agent: sl-mechanical | 2026-02-28
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//
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// Laser-cut or CNC-routed flat plate (6mm aluminium or 8mm acrylic).
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// Uses CALIPER-VERIFIED hub motor axle measurements — replaces placeholder
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// values from chassis_frame.scad (PR #7).
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//
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// ── VERIFIED AXLE PROFILE (stepped D-cut) ────────────────────────────────────
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// Zone │ Feature │ Diameter / Width │ Length
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// ───────┼──────────────────┼────────────────────┼─────────
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// Base │ Round (near hub) │ Ø 16.11 mm │ 15.00 mm
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// D-cut │ Round OD │ Ø 15.95 mm │ 43.35 mm
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// │ Flat chord │ 13.00 mm across │
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// Tip │ Shoulder/end │ — │ 3.00 mm (tip lock nut seat)
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// Total │ Hub face → tip │ — │ 65.50 mm
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// ───────┼──────────────────┼────────────────────┼─────────
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// Bearing seat collar OD: Ø 37.8 mm (hub centre)
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// Tire: 10 × 2.125" pneumatic (254 mm OD, 54 mm wide, 35 PSI)
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// =============================================================================
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$fn = 128;
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// =============================================================================
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// AXLE PARAMETERS — caliper-verified (edit only when re-measured)
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// =============================================================================
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AXLE_BASE_DIA = 16.11; // mm round section near hub face
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AXLE_BASE_LEN = 15.00; // mm length of base section
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AXLE_DCUT_DIA = 15.95; // mm round OD of D-cut zone
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AXLE_DCUT_FLAT = 13.00; // mm flat chord width (caliper across flat)
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AXLE_DCUT_LEN = 43.35; // mm D-cut section length
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AXLE_TIP_LEN = 3.00; // mm tip / shoulder
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AXLE_TOTAL = 65.50; // mm total protrusion from hub face
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BEARING_SEAT_OD = 37.80; // mm hub centre collar OD
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TIRE_OD = 254.0; // mm 10" × 25.4
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TIRE_WIDTH = 54.0; // mm 2.125" × 25.4
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AXLE_CL_HEIGHT = TIRE_OD / 2; // 127 mm — axle centre above ground
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// =============================================================================
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// PLATE PARAMETERS
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// =============================================================================
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WHEELBASE = 600.0; // mm axle C/L to axle C/L
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PLATE_DEPTH = 220.0; // mm front-to-rear
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PLATE_OVERHANG = 40.0; // mm plate extends past axle C/L on each side
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PLATE_THICK = 6.0; // mm stock thickness (6 mm Al / 8 mm acrylic)
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// Fork (open-ended slot in plate edge)
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// Width matched to base-section diameter + 0.4 mm running clearance
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FORK_W = AXLE_BASE_DIA + 0.4; // 16.51 mm
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FORK_DEPTH = 50.0; // mm slot depth inward from plate edge
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// Clamp block (two-piece sandwich, bolts through plate)
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CLAMP_L = 80.0; // mm along axle axis
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CLAMP_H = 60.0; // mm across axle (front-to-back of plate)
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CLAMP_THICK = 8.0; // mm each clamp layer — 8 mm Al or 10 mm acrylic
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CLAMP_BOLT_D = 5.3; // M5 clearance
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CLAMP_BOLT_DX = 22.0; // mm bolt ±X from axle C/L
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CLAMP_BOLT_DY = 22.0; // mm bolt ±Y from axle C/L (across plate)
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CLAMP_ALIGN_D = 4.1; // Ø4 alignment pin clearance
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// D-cut bore clearance (applied to both diameter and flat chord)
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DCUT_CL = 0.3; // mm all-round clearance on D-cut profile
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// FC mount — MAMBA F722S 30.5 × 30.5 mm M3 stack
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FC_PITCH = 30.5;
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FC_HOLE_D = 3.2;
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// Battery area — 24 V pack footprint (mount holes)
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BATT_L = 185.0;
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BATT_W = 72.0;
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// Utility
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M3 = 3.2; M4 = 4.3; M5 = 5.3;
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// =============================================================================
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// COMPUTED GEOMETRY (do not edit directly)
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// =============================================================================
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// D-cut bore geometry (with clearance):
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// r = (AXLE_DCUT_DIA + 2·DCUT_CL) / 2
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// fc = AXLE_DCUT_FLAT + 2·DCUT_CL (chord with clearance on each side)
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// d = distance from centre to flat = sqrt(r² – (fc/2)²)
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DCUT_R = (AXLE_DCUT_DIA + 2*DCUT_CL) / 2; // 8.275 mm
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DCUT_FC = AXLE_DCUT_FLAT + 2*DCUT_CL; // 13.60 mm
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// DCUT_D computed inside module (OpenSCAD has no sqrt at module-level constant)
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// Plate outer bounds
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PLATE_X_HALF = WHEELBASE/2 + PLATE_OVERHANG; // ± 340 mm
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// =============================================================================
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// RENDER CONTROL
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// =============================================================================
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// Set RENDER to one of:
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// "assembly" full 3-D preview (default)
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// "plate_2d" 2-D projection of base plate (→ DXF)
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// "clamp_lower_2d" 2-D projection of lower clamp (→ DXF)
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// "clamp_upper_2d" 2-D projection of upper clamp (→ DXF)
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RENDER = "assembly";
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if (RENDER == "assembly") {
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assembly();
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} else if (RENDER == "plate_2d") {
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projection(cut=true) translate([0,0,-PLATE_THICK/2]) base_plate();
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} else if (RENDER == "clamp_lower_2d") {
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projection(cut=true) translate([0,0,-CLAMP_THICK/2]) clamp_lower();
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} else if (RENDER == "clamp_upper_2d") {
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projection(cut=true) translate([0,0,-CLAMP_THICK/2]) clamp_upper();
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}
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// =============================================================================
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// ASSEMBLY
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// =============================================================================
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module assembly() {
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color("Silver", 0.85) base_plate();
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for (side = [-1, 1]) {
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// Lower clamp sits on top of base plate, below fork slot level
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color("SteelBlue", 0.8)
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translate([side * WHEELBASE/2, 0, PLATE_THICK])
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clamp_lower();
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// Upper clamp stacks on top of lower clamp
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color("CornflowerBlue", 0.8)
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translate([side * WHEELBASE/2, 0, PLATE_THICK + CLAMP_THICK])
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clamp_upper();
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}
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// Reference ghosts (not for export)
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%for (side = [-1, 1])
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color("Orange", 0.25)
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translate([side * WHEELBASE/2, 0, 0])
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rotate([0, side * 90, 0])
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axle_ghost();
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}
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// =============================================================================
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// BASE PLATE
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// =============================================================================
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module base_plate() {
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difference() {
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// ── Outer profile (rounded corners via minkowski) ──────────────────
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R = 12; // corner radius
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linear_extrude(PLATE_THICK)
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minkowski() {
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square([2*(PLATE_X_HALF - R), PLATE_DEPTH - 2*R], center=true);
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circle(r=R);
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}
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// ── Fork slots (open at ±X edges) ─────────────────────────────────
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// Slot is FORK_W wide, FORK_DEPTH deep, open at plate edge
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for (side = [-1, 1]) {
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// Round the slot tip (half-circle end)
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union() {
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translate([side*(PLATE_X_HALF - FORK_DEPTH),
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-FORK_W/2, -1])
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cube([FORK_DEPTH + 1, FORK_W, PLATE_THICK + 2]);
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// Semicircular slot bottom
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translate([side*(PLATE_X_HALF - FORK_DEPTH), 0, -1])
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cylinder(d=FORK_W, h=PLATE_THICK + 2);
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}
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}
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// ── Clamp bolt through-holes (4 per side × 2 sides) ────────────────
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for (side = [-1, 1])
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for (dx = [-CLAMP_BOLT_DX, CLAMP_BOLT_DX])
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for (dy = [-CLAMP_BOLT_DY, CLAMP_BOLT_DY])
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translate([side * WHEELBASE/2 + dx, dy, -1])
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cylinder(d=CLAMP_BOLT_D, h=PLATE_THICK + 2);
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// ── Alignment pin holes (Ø4, 2 per clamp side) ─────────────────────
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for (side = [-1, 1])
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for (dy = [-CLAMP_BOLT_DY + 8, CLAMP_BOLT_DY - 8])
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translate([side * WHEELBASE/2, dy, -1])
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cylinder(d=CLAMP_ALIGN_D, h=PLATE_THICK + 2);
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// ── FC mount holes (MAMBA F722S 30.5 × 30.5 M3) ────────────────────
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for (x = [-FC_PITCH/2, FC_PITCH/2])
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for (y = [-FC_PITCH/2, FC_PITCH/2])
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translate([x, y, -1])
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cylinder(d=FC_HOLE_D, h=PLATE_THICK + 2);
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// ── Battery tray mount holes (M4 × 4 corners) ──────────────────────
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for (x = [-BATT_L/2 + 12, BATT_L/2 - 12])
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for (y = [-BATT_W/2 + 10, BATT_W/2 - 10])
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translate([x, y, -1])
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cylinder(d=M4, h=PLATE_THICK + 2);
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// ── Lightening / cable routing slots (3 centre panels) ─────────────
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slot_w = 28;
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slot_h = PLATE_DEPTH - 80;
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for (x = [-130, 0, 130])
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translate([x - slot_w/2, -slot_h/2, -1])
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// Rounded slot via hull
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hull() {
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translate([slot_w/2, slot_w/2, 0]) cylinder(d=slot_w, h=PLATE_THICK+2);
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translate([slot_w/2, slot_h - slot_w/2, 0]) cylinder(d=slot_w, h=PLATE_THICK+2);
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}
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// ── Bearing seat relief (36mm slot lets hub collar clear plate edge) ─
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// Prevents Ø37.8mm bearing seat from binding against plate edge.
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for (side = [-1, 1])
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translate([side*PLATE_X_HALF - side*(BEARING_SEAT_OD/2 + 2),
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-BEARING_SEAT_OD/2, -1])
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cube([BEARING_SEAT_OD/2 + 3, BEARING_SEAT_OD, PLATE_THICK + 2]);
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}
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}
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// =============================================================================
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// DROPOUT CLAMP — LOWER (round bore, base-section diameter)
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// =============================================================================
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// Sits directly on top of the base plate.
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// The 16.11 mm round bore captures the base axle section.
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// The fork slot in the base plate is reproduced here to allow the axle to
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// slide in from the side.
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module clamp_lower() {
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difference() {
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// Body
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hull() {
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translate([-CLAMP_L/2 + CLAMP_H/2, 0, 0]) cylinder(d=CLAMP_H, h=CLAMP_THICK);
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translate([ CLAMP_L/2 - CLAMP_H/2, 0, 0]) cylinder(d=CLAMP_H, h=CLAMP_THICK);
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}
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// Round bore — base axle diameter + clearance
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translate([0, 0, -1])
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cylinder(d = AXLE_BASE_DIA + 0.4, h = CLAMP_THICK + 2);
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// Open entry slot (matches base plate fork slot — allows slide-in assembly)
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translate([-CLAMP_L/2 - 1, -FORK_W/2, -1])
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cube([CLAMP_L/2 + 1, FORK_W, CLAMP_THICK + 2]);
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// Clamp bolt holes
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for (dx = [-CLAMP_BOLT_DX, CLAMP_BOLT_DX])
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for (dy = [-CLAMP_BOLT_DY, CLAMP_BOLT_DY])
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translate([dx, dy, -1])
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cylinder(d=CLAMP_BOLT_D, h=CLAMP_THICK + 2);
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// Alignment pin holes
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for (dy = [-CLAMP_BOLT_DY + 8, CLAMP_BOLT_DY - 8])
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translate([0, dy, -1])
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cylinder(d=CLAMP_ALIGN_D, h=CLAMP_THICK + 2);
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}
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}
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// =============================================================================
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// DROPOUT CLAMP — UPPER (D-cut bore, anti-rotation)
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// =============================================================================
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// Stacks on top of lower clamp.
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// D-cut bore matches the caliper-verified profile:
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// Ø 15.95 mm round OD, 13.00 mm flat chord
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// Clearance DCUT_CL applied all-round.
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// The flat is oriented toward +Y (front of robot) — rotate clamp at assembly
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// to match actual flat position on your axles.
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module clamp_upper() {
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dcut_r = DCUT_R;
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dcut_fc = DCUT_FC;
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// Distance from bore CL to flat (chord geometry)
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dcut_d = sqrt(pow(dcut_r, 2) - pow(dcut_fc/2, 2));
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difference() {
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// Body (same footprint as lower clamp)
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hull() {
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translate([-CLAMP_L/2 + CLAMP_H/2, 0, 0]) cylinder(d=CLAMP_H, h=CLAMP_THICK);
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translate([ CLAMP_L/2 - CLAMP_H/2, 0, 0]) cylinder(d=CLAMP_H, h=CLAMP_THICK);
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}
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// D-cut bore:
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// 1. Full round circle of radius dcut_r
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// 2. Intersect with a box that removes the top (y > dcut_d)
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// Net result: D-shape with flat at +Y = dcut_d
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translate([0, 0, -1])
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linear_extrude(CLAMP_THICK + 2)
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dcut_profile_2d(dcut_r, dcut_d);
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// Open entry slot (same as lower clamp)
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translate([-CLAMP_L/2 - 1, -FORK_W/2, -1])
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cube([CLAMP_L/2 + 1, FORK_W, CLAMP_THICK + 2]);
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// Clamp bolt holes
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for (dx = [-CLAMP_BOLT_DX, CLAMP_BOLT_DX])
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for (dy = [-CLAMP_BOLT_DY, CLAMP_BOLT_DY])
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translate([dx, dy, -1])
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cylinder(d=CLAMP_BOLT_D, h=CLAMP_THICK + 2);
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// Alignment pin holes
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for (dy = [-CLAMP_BOLT_DY + 8, CLAMP_BOLT_DY - 8])
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translate([0, dy, -1])
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cylinder(d=CLAMP_ALIGN_D, h=CLAMP_THICK + 2);
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// Label emboss (orientation marker — "D-CUT" + flat side arrow)
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translate([-12, dcut_d + 1, CLAMP_THICK - 0.8])
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linear_extrude(1)
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text("D", size=6, font="Liberation Sans:style=Bold", halign="center");
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// Arrow indicating flat direction
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translate([8, dcut_d - 1, CLAMP_THICK - 0.8])
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linear_extrude(1)
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polygon([[0,0],[4,-3],[4,3]]);
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}
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}
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// ── 2-D D-cut profile helper ──────────────────────────────────────────────────
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// r = bore radius (with clearance already applied)
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// flat_d = distance from bore CL to flat (computed from chord geometry)
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module dcut_profile_2d(r, flat_d) {
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intersection() {
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circle(r=r);
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// Keep everything from y = -(r+1) up to y = flat_d
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translate([-r - 1, -r - 1])
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square([2*(r + 1), r + 1 + flat_d]);
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}
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}
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// =============================================================================
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// AXLE GHOST (for assembly visualisation)
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// =============================================================================
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module axle_ghost() {
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// Bearing seat collar
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cylinder(d=BEARING_SEAT_OD, h=12);
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// Base zone — round
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translate([0, 0, 12])
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cylinder(d=AXLE_BASE_DIA, h=AXLE_BASE_LEN);
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// D-cut zone (approximate cylinder for ghost)
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translate([0, 0, 12 + AXLE_BASE_LEN])
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cylinder(d=AXLE_DCUT_DIA, h=AXLE_DCUT_LEN);
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// Tip
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translate([0, 0, 12 + AXLE_BASE_LEN + AXLE_DCUT_LEN])
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cylinder(d=10, h=AXLE_TIP_LEN);
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}
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// =============================================================================
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// DXF / FLAT-PATTERN EXPORT GUIDE
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// =============================================================================
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//
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// PART 1 — Base plate
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// openscad prototype_baseplate.scad \
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// -D 'RENDER="plate_2d"' \
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// -o baseplate_plate.dxf
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//
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// PART 2 — Lower clamp (× 2, one per side)
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// openscad prototype_baseplate.scad \
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// -D 'RENDER="clamp_lower_2d"' \
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// -o baseplate_clamp_lower.dxf
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//
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// PART 3 — Upper clamp (× 2, one per side)
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// openscad prototype_baseplate.scad \
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// -D 'RENDER="clamp_upper_2d"' \
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// -o baseplate_clamp_upper.dxf
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//
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// MATERIAL NOTES
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// Base plate: 6 mm 5052-H32 aluminium (preferred)
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// 8 mm clear acrylic (quick prototype)
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// Clamp blocks: 8 mm 6061-T6 aluminium (preferred — tighter bore tolerance)
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// 10 mm PETG FDM (proto only — pre-drill bolt holes)
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//
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// LASER PARAMETERS (6 mm Al, fibre laser)
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// Power: 3 kW | Speed: 1800 mm/min | Assist: N2
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// Min bore dia: 6 mm (M5 holes OK)
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//
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// DIMENSIONAL NOTES
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// Fork slot width (FORK_W): 16.51 mm — verify on actual axle before cut
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// D-cut flat clearance (DCUT_CL): 0.3 mm — adjust if axle spins in clamp
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// Bearing seat relief: check collar actually clears plate edge before tightening
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// =============================================================================
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