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>
292 lines
14 KiB
OpenSCAD
292 lines
14 KiB
OpenSCAD
// ============================================================
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// base_bumper.scad — Base Plate Impact Bumper Rev A 2026-03-01
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// Agent: sl-mechanical
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// ============================================================
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// Clip-on bumper system for the 270×240 mm SaltyBot base plate.
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// Protects wheels, FC board, and wiring when robot tips.
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//
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// System overview:
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// corner_bracket() — L-clip, grips plate corner, print 4×
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// side_bracket() — straight clip for mid-sides, print 4×
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// tpu_edge_cap() — soft snap-on edge cap, print in TPU
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// (same profile fits corner and side)
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// bumper_rail_2d() — 2-D cross-section DXF for straight rails
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//
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// Assembly: 4 corner brackets + 4 side brackets clip onto the
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// plate bottom edge without drilling. Rails (printed or cut from
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// 25×8 mm aluminium bar) bridge between clips. TPU edge caps
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// snap onto rail outer face.
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//
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// FC status LEDs: FC is front-centre of plate. Bumper is below
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// and outside the plate footprint — LEDs remain visible.
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//
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// RENDER options:
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// "assembly" 3-D view with phantom plate (default)
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// "corner" one corner bracket (print 4×)
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// "side" one side bracket (print 4×)
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// "tpu_cap" TPU edge cap cross-section extruded (print N×)
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// "rail_2d" flat rail profile → DXF
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// ============================================================
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RENDER = "assembly";
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// ── Base plate (reference only — not printed) ─────────────────
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PLATE_W = 270.0; // width (motor axle direction, X)
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PLATE_D = 240.0; // depth (fore-aft, Y)
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PLATE_H = 6.0; // plate thickness
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PLATE_R = 10.0; // plate corner radius
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// ── Bumper geometry ──────────────────────────────────────────
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BUMP_H = 50.0; // bumper height below plate bottom face
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BUMP_T = 8.0; // rail/bracket wall thickness
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BUMP_CR = 22.0; // outer corner radius of bumper frame
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BUMP_EXTEND = 15.0; // how far bumper extends beyond plate edge
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// (absorbs impact before plate corner hits)
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// ── Clip channel (grips plate edge) ──────────────────────────
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CLIP_SLOT_W = PLATE_H + 0.6; // slot width (6 mm plate + 0.6 clearance)
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CLIP_SLOT_D = 12.0; // how deep clip grips plate edge
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CLIP_GRIP_T = 4.0; // clip wall above plate (keeps clip aligned)
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// ── Corner bracket ────────────────────────────────────────────
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CORNER_ARM = 45.0; // length of each L-arm along plate edge
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CORNER_H = BUMP_H + CLIP_GRIP_T + CLIP_SLOT_W;
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// ── Side bracket ─────────────────────────────────────────────
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SIDE_ARM = 30.0; // side bracket total width along plate edge
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SIDE_H = CORNER_H;
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// ── Rail (reference dims for procurement / DXF) ───────────────
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RAIL_W = BUMP_T; // 8 mm
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RAIL_H = BUMP_H; // 50 mm
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// ── TPU edge cap ─────────────────────────────────────────────
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CAP_W = BUMP_T + 4.0; // wraps around rail outer face
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CAP_H = 14.0; // cap height (bottom of bumper profile)
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CAP_R = 8.0; // outer impact radius
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CAP_CLIP_W = BUMP_T + 0.6; // inner clip width (snaps on rail)
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CAP_CLIP_D = 5.0; // clip depth
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// ── Fasteners ─────────────────────────────────────────────────
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M4_D = 4.5; // M4 clearance hole (rail → bracket)
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M3_D = 3.3; // M3 set screw (lock bracket on plate)
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$fn = 48;
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e = 0.01;
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// ─────────────────────────────────────────────────────────────
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// clip_slot_2d()
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// 2-D profile of the plate-edge gripping channel.
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// Origin at plate bottom face, +Y toward plate interior.
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// ─────────────────────────────────────────────────────────────
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module clip_slot_2d() {
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// Slot opens from outside (-Y), grips plate edge
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translate([0, -(BUMP_EXTEND + BUMP_T)])
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square([CLIP_SLOT_W, CLIP_SLOT_D + BUMP_EXTEND + BUMP_T]);
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}
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// ─────────────────────────────────────────────────────────────
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// corner_bracket()
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// L-shaped clip bracket. Internal coordinate:
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// Corner at origin, arms along +X and +Y.
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// Plate sits at Z = BUMP_H (above bracket base).
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// ─────────────────────────────────────────────────────────────
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module corner_bracket() {
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arm_w = BUMP_T; // wall thickness
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arm_h = CORNER_H; // full height
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difference() {
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union() {
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// X arm (along plate width edge)
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translate([-BUMP_EXTEND, -BUMP_EXTEND, 0])
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hull() {
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cube([CORNER_ARM + BUMP_EXTEND, arm_w, arm_h]);
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translate([0, arm_w, 0])
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cylinder(r = BUMP_CR, h = arm_h);
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translate([CORNER_ARM + BUMP_EXTEND, arm_w, 0])
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cylinder(r = BUMP_CR, h = arm_h);
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}
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// Y arm (along plate depth edge)
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translate([-BUMP_EXTEND, -BUMP_EXTEND, 0])
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hull() {
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cube([arm_w, CORNER_ARM + BUMP_EXTEND, arm_h]);
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translate([arm_w, 0, 0])
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cylinder(r = BUMP_CR, h = arm_h);
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translate([arm_w, CORNER_ARM + BUMP_EXTEND, 0])
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cylinder(r = BUMP_CR, h = arm_h);
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}
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}
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// Clip slot in X arm (grips plate edge)
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// Slot at Z = BUMP_H (plate bottom face height)
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translate([CORNER_ARM - CLIP_SLOT_D, -(BUMP_EXTEND + arm_w + e), BUMP_H])
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cube([CLIP_SLOT_D + BUMP_EXTEND + e,
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arm_w + 2*e, CLIP_SLOT_W]);
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// Clip slot in Y arm
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translate([-(BUMP_EXTEND + arm_w + e), CORNER_ARM - CLIP_SLOT_D, BUMP_H])
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cube([arm_w + 2*e,
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CLIP_SLOT_D + BUMP_EXTEND + e, CLIP_SLOT_W]);
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// M3 set screw through clip above slot (X arm, 2 per arm)
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for (xoff = [CORNER_ARM * 0.3, CORNER_ARM * 0.7]) {
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translate([xoff - BUMP_EXTEND, -(BUMP_EXTEND + arm_w/2), BUMP_H + CLIP_SLOT_W + CLIP_GRIP_T/2])
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rotate([90, 0, 0])
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cylinder(d = M3_D, h = arm_w + 2*e);
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}
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for (yoff = [CORNER_ARM * 0.3, CORNER_ARM * 0.7]) {
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translate([-(BUMP_EXTEND + arm_w/2), yoff - BUMP_EXTEND, BUMP_H + CLIP_SLOT_W + CLIP_GRIP_T/2])
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rotate([0, 90, 0])
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cylinder(d = M3_D, h = arm_w + 2*e);
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}
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// M4 holes for rail attachment (outer face, pairs per arm)
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for (xoff = [15, CORNER_ARM - 10]) {
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translate([xoff - BUMP_EXTEND, -(BUMP_EXTEND + arm_w + e), BUMP_H * 0.3])
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rotate([90, 0, 0])
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cylinder(d = M4_D, h = arm_w + 2*e);
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translate([xoff - BUMP_EXTEND, -(BUMP_EXTEND + arm_w + e), BUMP_H * 0.7])
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rotate([90, 0, 0])
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cylinder(d = M4_D, h = arm_w + 2*e);
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}
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}
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}
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// ─────────────────────────────────────────────────────────────
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// side_bracket()
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// Straight clip for mid-side. Grips plate edge, M4 holes
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// for rail, M3 set screws. Placed between corner brackets.
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// ─────────────────────────────────────────────────────────────
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module side_bracket() {
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arm_w = BUMP_T;
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arm_h = SIDE_H;
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difference() {
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// Outer body
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translate([-SIDE_ARM/2, -(BUMP_EXTEND + arm_w), 0])
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hull() {
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cube([SIDE_ARM, arm_w, arm_h]);
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translate([0, arm_w, 0])
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cylinder(r = BUMP_CR * 0.6, h = arm_h);
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translate([SIDE_ARM, arm_w, 0])
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cylinder(r = BUMP_CR * 0.6, h = arm_h);
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}
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// Clip slot
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translate([-SIDE_ARM/2 + 5, -(BUMP_EXTEND + arm_w + e), BUMP_H])
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cube([SIDE_ARM - 10, arm_w + 2*e, CLIP_SLOT_W]);
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// M3 set screws (2×)
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for (xoff = [-SIDE_ARM/4, SIDE_ARM/4]) {
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translate([xoff, -(BUMP_EXTEND + arm_w/2), BUMP_H + CLIP_SLOT_W + CLIP_GRIP_T/2])
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rotate([90, 0, 0])
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cylinder(d = M3_D, h = arm_w + 2*e);
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}
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// M4 rail holes (2 heights × 1 column)
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for (zh = [BUMP_H * 0.3, BUMP_H * 0.7]) {
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translate([0, -(BUMP_EXTEND + arm_w + e), zh])
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rotate([90, 0, 0])
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cylinder(d = M4_D, h = arm_w + 2*e);
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}
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}
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}
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// ─────────────────────────────────────────────────────────────
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// tpu_edge_cap()
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// Snap-on soft edge cap — print in TPU.
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// Snaps onto outer face of rail (or corner bracket outer face).
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// Orient: cap opening faces -Y (toward bracket), print flat.
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// ─────────────────────────────────────────────────────────────
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module tpu_edge_cap() {
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// Length — 40 mm segment; print multiple, install end-to-end
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cap_len = 40.0;
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difference() {
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union() {
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// Rounded outer impact face
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hull() {
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translate([-CAP_W/2, 0, 0])
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cylinder(r = CAP_R, h = cap_len);
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translate([ CAP_W/2, 0, 0])
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cylinder(r = CAP_R, h = cap_len);
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translate([-CAP_W/2, CAP_H - CAP_R, 0])
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cylinder(r = CAP_R, h = cap_len);
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translate([ CAP_W/2, CAP_H - CAP_R, 0])
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cylinder(r = CAP_R, h = cap_len);
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}
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}
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// Inner clip slot (snaps onto rail outer face)
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translate([-CAP_CLIP_W/2, -e, -e])
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cube([CAP_CLIP_W, CAP_CLIP_D + e, cap_len + 2*e]);
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}
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}
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// ─────────────────────────────────────────────────────────────
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// bumper_rail_2d()
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// 2-D profile for straight bumper rail sections.
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// Extrude to length per side: front/rear = PLATE_W, sides = PLATE_D.
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// Use "rail_2d" RENDER to export DXF.
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// ─────────────────────────────────────────────────────────────
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module bumper_rail_2d() {
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// Simple rectangular profile 8 × 50 mm
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square([RAIL_W, RAIL_H]);
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}
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// ─────────────────────────────────────────────────────────────
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// Phantom plate (reference, assembly view only)
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// ─────────────────────────────────────────────────────────────
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module phantom_plate() {
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color("Gray", 0.25)
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linear_extrude(PLATE_H)
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offset(r = PLATE_R, $fn = 32)
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offset(-PLATE_R)
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square([PLATE_W, PLATE_D], center = true);
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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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// Phantom plate
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translate([0, 0, BUMP_H]) phantom_plate();
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// 4 corner brackets (NW / NE / SW / SE)
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half_w = PLATE_W/2;
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half_d = PLATE_D/2;
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color("SteelBlue", 0.9) {
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// NW corner (X−, Y+) → rotate 90°
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translate([-half_w, half_d, 0]) rotate([0,0,180]) corner_bracket();
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// NE corner (X+, Y+) → rotate 90°
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translate([ half_w, half_d, 0]) rotate([0,0,270]) corner_bracket();
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// SW corner (X−, Y−) → no rotation
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translate([-half_w,-half_d, 0]) rotate([0,0, 90]) corner_bracket();
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// SE corner (X+, Y−)
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translate([ half_w,-half_d, 0]) corner_bracket();
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}
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// 4 side brackets (front, rear, left, right midpoints)
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color("CornflowerBlue", 0.9) {
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translate([0, half_d, 0]) rotate([0,0,180]) side_bracket(); // front
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translate([0, -half_d, 0]) side_bracket(); // rear
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translate([-half_w, 0, 0]) rotate([0,0, 90]) side_bracket(); // left
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translate([ half_w, 0, 0]) rotate([0,0,270]) side_bracket(); // right
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}
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} else if (RENDER == "corner") {
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corner_bracket();
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} else if (RENDER == "side") {
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side_bracket();
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} else if (RENDER == "tpu_cap") {
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tpu_edge_cap();
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} else if (RENDER == "rail_2d") {
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projection(cut = false)
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linear_extrude(1)
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bumper_rail_2d();
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}
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