sl-mechanical
beb0af7ce6
Protects expensive sensors when robot tips over during testing.
Files added:
chassis/bumper_frame.scad — roll cage (25 mm stem collar + 4 inclined
posts + crown ring + TPU snap pad). Posts at
45/135/225/315° between cameras. Crown at
Z=148 mm above cage collar, 18 mm above RPLIDAR
top. RPLIDAR FOV unobstructed.
chassis/base_bumper.scad — clip-on bumper ring for 270×240 mm base plate.
50 mm tall, 15 mm standoff, rounded corners.
4× corner + 4× side clip brackets. TPU snap
edge caps. FC status LEDs remain visible.
chassis/stem_protector.scad — split TPU sleeve for 25 mm stem. Snap-fit
closure (no hardware). Install 3–4 sleeves
along stem at ~200 mm intervals.
chassis/bumper_BOM.md — full BOM, print settings, install heights,
mass estimate (~500 g total, balanced).
All parts print without supports. Fully removable (clip/snap/clamp).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
261 lines
12 KiB
OpenSCAD
261 lines
12 KiB
OpenSCAD
// ============================================================
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// bumper_frame.scad — Sensor Head Roll Cage Rev A 2026-03-01
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// Agent: sl-mechanical
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// ============================================================
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// Roll cage for SaltyBot sensor head (25 mm OD stem).
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// Protects RPLIDAR A1M8, RealSense D435i, and 4× IMX219 cameras
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// when the robot tips over.
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//
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// Cage posts sit at 45°/135°/225°/315° (between camera arms at
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// 0°/90°/180°/270°), minimising camera FOV obstruction.
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// Crown ring sits ABOVE the RPLIDAR top — no scan-plane crossing.
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// Posts lean outward so they are outside RPLIDAR body radius at
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// scan-plane height.
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//
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// Component overview:
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// cage_collar_half() — split stem collar, print 2×
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// cage_post() — inclined rib, print 4×, lay flat
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// cage_crown() — flat ring above RPLIDAR, print 1×
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// tpu_crown_pad() — snap-on TPU impact strip, print in TPU
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//
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// RENDER options:
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// "assembly" full 3-D view (default)
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// "collar_front" front collar half for slicing
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// "collar_rear" rear collar half for slicing
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// "post" single post for slicing (print 4×)
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// "crown" crown ring for slicing
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// "tpu_pad" TPU snap strip for slicing
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// ============================================================
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RENDER = "assembly";
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// ── Stem ─────────────────────────────────────────────────────
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STEM_OD = 25.0;
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STEM_BORE = 25.5; // +0.5 mm clearance (collar slides easily)
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// ── Cage collar ──────────────────────────────────────────────
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COL_OD = 52.0;
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COL_H = 24.0; // height (shorter than sensor-head collar)
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COL_BOLT_X = 19.0; // M4 clamping bolt CL from stem axis (X)
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COL_BOLT_D = 4.5; // M4 clearance
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COL_NUT_W = 7.0; // M4 hex nut A/F
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COL_NUT_H = 3.4; // M4 hex nut thickness
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// Post attachment boss on collar outer surface
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// Boss at 45°/135°/225°/315°, protrudes POST_BOSS_H radially
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POST_BOSS_H = 6.0;
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POST_BOSS_W = 14.0; // boss width (tangential)
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POST_BOSS_Z = 6.0; // boss bottom offset from collar base
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POST_BOSS_HT = COL_H - POST_BOSS_Z - 4; // boss height on collar
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// ── Cage post ────────────────────────────────────────────────
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POST_BASE_R = COL_OD/2 + POST_BOSS_H; // radial start of post CL
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POST_TIP_R = 108.0; // radial end of post at crown height
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CROWN_Z = 148.0; // height of crown ring (above collar base)
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// RPLIDAR top is ~120 mm above cage collar
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POST_W = 12.0; // post width (tangential)
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POST_T = 8.0; // post thickness (radial)
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POST_LEN = sqrt(pow(POST_TIP_R - POST_BASE_R, 2) + pow(CROWN_Z, 2));
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POST_LEAN = atan((POST_TIP_R - POST_BASE_R) / CROWN_Z); // ~25° from vertical
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// At RPLIDAR scan height (~105 mm), post is at radius:
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// POST_BASE_R + (POST_TIP_R - POST_BASE_R) * (105/CROWN_Z) ≈ 78 mm
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// >> RPLIDAR body radius 35 mm — no scan-plane intersection
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POST_BOLT_D = 4.5; // M4 clearance at each post end
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// ── Crown ring ───────────────────────────────────────────────
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CROWN_OD = 230.0; // crown outer diameter
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CROWN_ID = 206.0; // crown inner diameter
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CROWN_RH = 12.0; // crown ring height (thickness)
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CROWN_PAD_D = 10.0; // TPU pad snap channel diameter (semi-circle)
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CROWN_PAD_INSET = 5.0; // inset from crown outer edge
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// Post socket: slot in crown ring where post tip inserts
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SOCK_W = POST_W + 0.4; // slot width (clearance)
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SOCK_D = POST_T + 0.4; // slot depth
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SOCK_H = CROWN_RH; // full ring thickness
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// ── TPU crown pad ────────────────────────────────────────────
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PAD_ID = CROWN_OD - 2 * CROWN_PAD_INSET;
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PAD_OD = CROWN_OD + 2.0;
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PAD_H = CROWN_PAD_D + 2.0;
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$fn = 64;
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e = 0.01;
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// ─────────────────────────────────────────────────────────────
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// cage_collar_half(side)
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// side = "front" (+Y) | "rear" (-Y)
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// Print flat-face-down.
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// ─────────────────────────────────────────────────────────────
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module cage_collar_half(side = "front") {
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y_front = (side == "front");
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y_sign = y_front ? 1 : -1;
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difference() {
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union() {
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// D-shaped half body
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intersection() {
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cylinder(d = COL_OD, h = COL_H);
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translate([-COL_OD/2, y_front ? 0 : -COL_OD/2, 0])
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cube([COL_OD, COL_OD/2, COL_H]);
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}
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// Post attachment bosses at 45° and 135° (front) / 225° and 315° (rear)
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for (a = y_front ? [45, -45] : [135, -135]) {
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rotate([0, 0, a])
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translate([COL_OD/2, -POST_BOSS_W/2, POST_BOSS_Z])
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cube([POST_BOSS_H, POST_BOSS_W, POST_BOSS_HT]);
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}
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}
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// Stem bore
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translate([0, 0, -e])
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cylinder(d = STEM_BORE, h = COL_H + 2*e);
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// M4 clamping bolt holes (Y direction through mating face)
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for (bx = [-COL_BOLT_X, COL_BOLT_X]) {
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translate([bx, y_front ? COL_OD/2 : 0, COL_H/2])
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rotate([90, 0, 0])
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cylinder(d = COL_BOLT_D, h = COL_OD/2 + e);
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}
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// M4 hex nut pockets in rear half
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if (!y_front) {
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for (bx = [-COL_BOLT_X, COL_BOLT_X]) {
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translate([bx, -(COL_OD/4 + e), COL_H/2])
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rotate([90, 0, 0])
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cylinder(d = COL_NUT_W / cos(30), h = COL_NUT_H + e, $fn = 6);
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}
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}
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// M4 set screw (front only, outer face → stem bore)
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if (y_front) {
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translate([0, COL_OD/2, COL_H * 0.7])
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rotate([90, 0, 0])
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cylinder(d = COL_BOLT_D, h = COL_OD/2 - STEM_BORE/2 + e);
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}
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// M4 post attachment hole through each boss (radial direction)
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for (a = y_front ? [45, -45] : [135, -135]) {
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rotate([0, 0, a])
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translate([COL_OD/2 + e, 0, POST_BOSS_Z + POST_BOSS_HT/2])
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rotate([0, -90, 0])
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cylinder(d = POST_BOLT_D, h = POST_BOSS_H + COL_OD/8 + e);
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}
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}
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}
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// ─────────────────────────────────────────────────────────────
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// cage_post()
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// For assembly: placed radially at angle a.
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// For slicing ("post" RENDER): printed lying flat on XY plane.
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// ─────────────────────────────────────────────────────────────
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module cage_post_geometry() {
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// Post spans from base (r = POST_BASE_R, z = 0) to tip (r = POST_TIP_R, z = CROWN_Z)
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// Width POST_W in tangential direction, thickness POST_T in radial direction
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difference() {
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hull() {
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translate([POST_BASE_R, -POST_W/2, 0])
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cube([POST_T, POST_W, 1]);
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translate([POST_TIP_R, -POST_W/2, CROWN_Z - 1])
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cube([POST_T, POST_W, 1]);
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}
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// M4 hole at base end (through POST_T, radially)
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translate([POST_BASE_R + POST_T/2, 0, POST_BOSS_Z + POST_BOSS_HT/2])
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rotate([0, 90, 0])
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cylinder(d = POST_BOLT_D, h = POST_T + 2*e, center = true);
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// M4 hole at tip end
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translate([POST_TIP_R + POST_T/2, 0, CROWN_Z - CROWN_RH/2])
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rotate([0, 90, 0])
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cylinder(d = POST_BOLT_D, h = POST_T + 2*e, center = true);
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// TPU pad snap groove on outer (high-r) face — runs along post length
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// Groove: 5 mm wide × 2.5 mm deep semi-channel at midspan
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translate([POST_TIP_R + POST_T - 0.1, -2.5, CROWN_Z * 0.3])
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cube([3, 5, CROWN_Z * 0.4]);
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}
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}
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// ─────────────────────────────────────────────────────────────
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// cage_crown()
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// Flat ring. 4 post sockets at 45/135/225/315°.
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// TPU snap channel on outer rim.
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// ─────────────────────────────────────────────────────────────
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module cage_crown() {
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difference() {
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cylinder(d = CROWN_OD, h = CROWN_RH, $fn = 8);
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// Hollow centre
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translate([0, 0, -e])
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cylinder(d = CROWN_ID, h = CROWN_RH + 2*e);
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// 4 post-tip sockets at 45/135/225/315°
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for (a = [45, 135, 225, 315]) {
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rotate([0, 0, a])
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translate([CROWN_ID/2 + (CROWN_OD-CROWN_ID)/4 - SOCK_D/2,
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-SOCK_W/2, -e])
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cube([SOCK_D + e, SOCK_W, SOCK_H + 2*e]);
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}
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// 2× M4 bolts per post socket (through ring top to post)
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for (a = [45, 135, 225, 315]) {
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rotate([0, 0, a])
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for (dw = [-POST_W/4, POST_W/4])
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translate([CROWN_ID/2 + (CROWN_OD-CROWN_ID)/4,
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dw, -e])
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cylinder(d = POST_BOLT_D, h = CROWN_RH + 2*e);
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}
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// TPU snap channel — semicircular groove on outer rim top face
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translate([0, 0, CROWN_RH - CROWN_PAD_D/2])
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rotate_extrude()
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translate([CROWN_OD/2 - CROWN_PAD_INSET, 0])
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circle(d = CROWN_PAD_D);
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}
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}
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// ─────────────────────────────────────────────────────────────
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// tpu_crown_pad() — print in TPU, snaps into crown channel
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// ─────────────────────────────────────────────────────────────
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module tpu_crown_pad() {
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// Ring with round cross-section slightly larger than channel
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rotate_extrude()
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translate([PAD_ID/2 + (PAD_OD - PAD_ID)/2 - CROWN_PAD_INSET, 0])
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circle(d = CROWN_PAD_D * 1.15); // slight interference for snap
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}
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// ─────────────────────────────────────────────────────────────
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// Render selector
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// ─────────────────────────────────────────────────────────────
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if (RENDER == "assembly") {
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color("SkyBlue", 0.9) cage_collar_half("front");
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color("DodgerBlue", 0.9) mirror([0,1,0]) cage_collar_half("rear");
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for (a = [45, 135, 225, 315])
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color("LightGray", 0.85)
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rotate([0, 0, a]) cage_post_geometry();
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color("Silver", 0.9) translate([0, 0, CROWN_Z]) cage_crown();
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color("OrangeRed", 0.7) translate([0, 0, CROWN_Z + CROWN_RH - CROWN_PAD_D/2])
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tpu_crown_pad();
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} else if (RENDER == "collar_front") {
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cage_collar_half("front");
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} else if (RENDER == "collar_rear") {
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cage_collar_half("rear");
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} else if (RENDER == "post") {
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// Orient flat for slicing: long axis along X, flat face on Z=0
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rotate([0, 0, -45]) // un-rotate from assembly angle
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rotate([-90, 0, 0]) // lay flat
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cage_post_geometry();
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} else if (RENDER == "crown") {
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cage_crown();
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} else if (RENDER == "tpu_pad") {
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tpu_crown_pad();
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}
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