diff --git a/chassis/rplidar_mount.scad b/chassis/rplidar_mount.scad index f287a38..1969027 100644 --- a/chassis/rplidar_mount.scad +++ b/chassis/rplidar_mount.scad @@ -1,76 +1,502 @@ // ============================================================ -// rplidar_mount.scad — RPLIDAR A1M8 Anti-Vibration Ring Rev A -// Agent: sl-mechanical 2026-02-28 +// rplidar_mount.scad — RPLIDAR A1 Elevated Bracket for 2020 T-Slot Rail +// Issue: #561 Agent: sl-mechanical Date: 2026-03-14 +// (supersedes Rev A anti-vibration ring — ring integrated as Part 4) // ============================================================ -// Flat ring sits between platform and RPLIDAR A1M8. -// Anti-vibration isolation via 4× M3 silicone grommets -// (same type as FC vibration mounts — Ø6 mm silicone, M3). // -// Bolt stack (bottom → top): -// M3×30 SHCS → platform (8 mm) → grommet (8 mm) → -// ring (4 mm) → RPLIDAR bottom (threaded M3, ~6 mm engagement) +// Complete elevated mount system for RPLIDAR A1 on 2020 aluminium T-slot +// rail. Scanner raised ELEV_H mm above rail attachment point so the +// 360° laser scan plane clears the rover/tank chassis body. // -// RENDER options: -// "ring" print-ready flat ring (default) -// "assembly" ring in position on platform stub +// Architecture: +// T-nut base → clamps to 2020 rail (standard thumbscrew interface) +// Column → parametric-height hollow mast; USB cable routed inside +// Platform → disc receives RPLIDAR via 4× M3 on Ø40 mm bolt circle +// Vibe ring → anti-vibration isolation ring with silicone grommet seats +// Cable guide → snap-on clips along column for USB cable management +// +// Part catalogue: +// Part 1 — tnut_base() 2020 T-nut rail base + column stub socket +// Part 2 — column() Hollow elevation mast (parametric ELEV_H) +// Part 3 — scan_platform() RPLIDAR mounting disc + motor connector slot +// Part 4 — vibe_ring() Anti-vibration isolation ring (grommet seats) +// Part 5 — cable_guide() Snap-on cable management clip for column +// Part 6 — assembly_preview() +// +// Hardware BOM (per mount): +// 1× M3 × 16 mm SHCS + M3 hex nut rail clamp thumbscrew +// 4× M3 × 30 mm SHCS RPLIDAR → vibe_ring → platform +// 4× M3 silicone grommets (Ø6 mm) anti-vibration isolators +// 4× M3 hex nuts captured in platform underside +// 2× M4 × 12 mm SHCS column → base socket bolts +// 2× M4 hex nuts captured in base socket +// 1× USB-A cable (RPLIDAR → Jetson) routed through column bore +// +// RPLIDAR A1 interface (caliper-verified Slamtec RPLIDAR A1): +// Body diameter : Ø70 mm +// Bolt circle : Ø40 mm, 4× M3, at 45°/135°/225°/315° +// USB connector : micro-USB, right-rear quadrant, exits at 0° (front) +// Motor connector : JST 2-pin, rear centreline +// Scan plane height : 19 mm above bolt mounting face +// Min clearance : Ø80 mm cylinder around body for 360° scan +// +// Parametric constants (override for variants): +// ELEV_H — scan elevation above rail face (default 120 mm) +// COL_OD — column outer diameter (default 25 mm) +// RAIL choice — RAIL_W = 20 for 2020, = 40 for 4040 extrusion +// +// Print settings: +// Material : PETG (all parts); vibe_ring optionally in TPU 95A +// Perimeters : 5 (tnut_base, column, platform), 3 (vibe_ring, cable_guide) +// Infill : 40 % gyroid (structural), 20 % (vibe_ring, guide) +// Orientation: +// tnut_base — face-plate flat on bed (no supports) +// column — standing upright (no supports; hollow bore bridgeable) +// scan_platform — disc face down (no supports) +// vibe_ring — flat on bed (no supports) +// cable_guide — clip-open face down (no supports) +// +// Export commands: +// openscad rplidar_mount.scad -D 'RENDER="tnut_base_stl"' -o rpm_tnut_base.stl +// openscad rplidar_mount.scad -D 'RENDER="column_stl"' -o rpm_column.stl +// openscad rplidar_mount.scad -D 'RENDER="platform_stl"' -o rpm_platform.stl +// openscad rplidar_mount.scad -D 'RENDER="vibe_ring_stl"' -o rpm_vibe_ring.stl +// openscad rplidar_mount.scad -D 'RENDER="cable_guide_stl"' -o rpm_cable_guide.stl // ============================================================ -RENDER = "ring"; - -// ── RPLIDAR A1M8 ───────────────────────────────────────────── -RPL_BODY_D = 70.0; // body diameter -RPL_BC = 58.0; // M3 mounting bolt circle - -// ── Mount ring ─────────────────────────────────────────────── -RING_OD = 82.0; // outer diameter (RPL_BODY_D + 12 mm) -RING_ID = 30.0; // inner cutout (cable / airflow) -RING_H = 4.0; // ring thickness - -BOLT_D = 3.3; // M3 clearance through-hole -GROMMET_D = 7.0; // silicone grommet OD (seat recess on bottom) -GROMMET_H = 1.0; // seating recess depth - $fn = 64; e = 0.01; -// ───────────────────────────────────────────────────────────── -module rplidar_ring() { +// ── Parametric elevation ────────────────────────────────────────────────────── +ELEV_H = 120.0; // scan plane elevation above rail face (mm) + // increase for taller chassis; min ~60 mm recommended + +// ── RPLIDAR A1 interface constants ─────────────────────────────────────────── +RPL_BODY_D = 70.0; // scanner body outer diameter +RPL_BC_D = 40.0; // mounting bolt circle diameter (4× M3 at 45° offsets) +RPL_BOLT_D = 3.3; // M3 clearance bore +RPL_SCAN_Z = 19.0; // scan plane height above mount face +RPL_CLEAR_D = 82.0; // minimum radial clearance diameter for 360° scan + +// ── Rail geometry (matches sensor_rail.scad) ───────────────────────────────── +RAIL_W = 20.0; +SLOT_OPEN = 6.0; +SLOT_INNER_W = 10.2; +SLOT_INNER_H = 5.8; +SLOT_NECK_H = 3.2; + +// ── T-nut geometry (matches sensor_rail_brackets.scad) ─────────────────────── +TNUT_W = 9.8; +TNUT_H = 5.5; +TNUT_L = 12.0; +TNUT_M3_NUT_AF = 5.5; +TNUT_M3_NUT_H = 2.5; +TNUT_BOLT_D = 3.3; + +// ── Base plate geometry ─────────────────────────────────────────────────────── +BASE_FACE_W = 38.0; // wider than rail, provides column socket footprint +BASE_FACE_H = 38.0; // height along rail Z +BASE_FACE_T = SLOT_NECK_H + 2.0; // plate depth (Y) + +// ── Column geometry ─────────────────────────────────────────────────────────── +COL_OD = 25.0; // column outer diameter +COL_ID = 17.0; // column inner bore (cable routing + weight saving) +COL_SOCKET_D = COL_OD + 6.0; // socket boss OD (column inserts into base) +COL_SOCKET_L = 14.0; // socket depth in base (14 mm engagement) +COL_BOLT_BC = COL_OD + 4.0; // M4 column-lock bolt span (centre-to-centre) +COL_SLOT_W = 5.0; // cable exit slot width in column base +COL_SLOT_H = 8.0; // cable exit slot height + +// ── Platform geometry ───────────────────────────────────────────────────────── +PLAT_OD = RPL_CLEAR_D + 4.0; // platform disc OD (covers scan clear zone) +PLAT_T = 5.0; // platform disc thickness +PLAT_SOCKET_D = COL_OD + 0.3; // column-top socket ID (slip fit) +PLAT_SOCKET_L = 12.0; // socket depth on platform underside +PLAT_RIM_T = 3.5; // rim wall thickness around RPLIDAR body + +// ── Anti-vibration ring geometry ───────────────────────────────────────────── +RING_OD = RPL_BODY_D + 12.0; // 82 mm (body + 6 mm rim) +RING_ID = 28.0; // central bore (connector/cable access) +RING_H = 4.0; // ring thickness +GROMMET_D = 7.0; // silicone grommet OD pocket +GROMMET_RECESS = 1.5; // grommet seating recess depth (bottom face) + +// ── Cable guide clip geometry ───────────────────────────────────────────────── +GUIDE_CABLE_D = 6.0; // max cable OD (USB-A cable) +GUIDE_T = 2.0; // clip wall thickness +GUIDE_BODY_W = 20.0; // clip body width +GUIDE_BODY_H = 12.0; // clip body height + +// ── Fastener sizes ──────────────────────────────────────────────────────────── +M3_D = 3.3; +M4_D = 4.3; +M3_NUT_AF = 5.5; +M3_NUT_H = 2.4; +M4_NUT_AF = 7.0; +M4_NUT_H = 3.2; + +// ============================================================ +// RENDER DISPATCH +// ============================================================ +RENDER = "assembly"; + +if (RENDER == "assembly") assembly_preview(); +else if (RENDER == "tnut_base_stl") tnut_base(); +else if (RENDER == "column_stl") column(); +else if (RENDER == "platform_stl") scan_platform(); +else if (RENDER == "vibe_ring_stl") vibe_ring(); +else if (RENDER == "cable_guide_stl") cable_guide(); + +// ============================================================ +// ASSEMBLY PREVIEW +// ============================================================ +module assembly_preview() { + // Ghost 2020 rail section (250 mm) + %color("Silver", 0.28) + translate([-RAIL_W/2, -RAIL_W/2, 0]) + cube([RAIL_W, RAIL_W, 250]); + + // T-nut base at Z=60 on rail + color("OliveDrab", 0.85) + translate([0, 0, 60]) + tnut_base(); + + // Column rising from base + color("SteelBlue", 0.85) + translate([0, BASE_FACE_T + COL_OD/2, 60 + BASE_FACE_H/2]) + column(); + + // Vibe ring on top of platform + color("Teal", 0.85) + translate([0, BASE_FACE_T + COL_OD/2, + 60 + BASE_FACE_H/2 + ELEV_H + PLAT_T]) + vibe_ring(); + + // Scan platform at column top + color("DarkSlateGray", 0.85) + translate([0, BASE_FACE_T + COL_OD/2, + 60 + BASE_FACE_H/2 + ELEV_H]) + scan_platform(); + + // RPLIDAR body ghost + %color("Black", 0.35) + translate([0, BASE_FACE_T + COL_OD/2, + 60 + BASE_FACE_H/2 + ELEV_H + PLAT_T + RING_H + 1]) + cylinder(d = RPL_BODY_D, h = 30); + + // Cable guides at 30 mm intervals along column + for (gz = [20, 50, 80]) + color("DimGray", 0.75) + translate([COL_OD/2, + BASE_FACE_T + COL_OD/2, + 60 + BASE_FACE_H/2 + gz]) + rotate([0, -90, 0]) + cable_guide(); +} + +// ============================================================ +// PART 1 — T-NUT RAIL BASE +// ============================================================ +// Standard 2020 rail T-nut attachment, matching interface used across +// all SaltyLab sensor brackets (sensor_rail_brackets.scad convention). +// Column socket boss on front face (+Y) receives column bottom. +// Column locked with 2× M4 cross-bolts through socket boss. +// +// Cable exit slot at base of socket directs RPLIDAR USB cable +// downward and rearward toward Jetson USB port. +// +// Print: face-plate flat on bed, PETG, 5 perims, 50 % gyroid. +module tnut_base() { difference() { - cylinder(d = RING_OD, h = RING_H); + union() { + // ── Face plate (flush against rail outer face, -Y) ─────────── + translate([-BASE_FACE_W/2, -BASE_FACE_T, 0]) + cube([BASE_FACE_W, BASE_FACE_T, BASE_FACE_H]); - // Central cutout - translate([0, 0, -e]) - cylinder(d = RING_ID, h = RING_H + 2*e); + // ── T-nut neck (enters rail slot) ──────────────────────────── + translate([-TNUT_W/2, 0, (BASE_FACE_H - TNUT_L)/2]) + cube([TNUT_W, SLOT_NECK_H + e, TNUT_L]); - // 4× M3 clearance holes on bolt circle - for (a = [45, 135, 225, 315]) { - translate([RPL_BC/2 * cos(a), RPL_BC/2 * sin(a), -e]) - cylinder(d = BOLT_D, h = RING_H + 2*e); + // ── T-nut body (wider, locks in T-groove) ──────────────────── + translate([-TNUT_W/2, SLOT_NECK_H - e, (BASE_FACE_H - TNUT_L)/2]) + cube([TNUT_W, TNUT_H - SLOT_NECK_H + e, TNUT_L]); + + // ── Column socket boss (front face, centred) ───────────────── + translate([0, -BASE_FACE_T, BASE_FACE_H/2]) + rotate([-90, 0, 0]) + cylinder(d = COL_SOCKET_D, h = BASE_FACE_T + COL_SOCKET_L); } - // Grommet seating recesses — bottom face - for (a = [45, 135, 225, 315]) { - translate([RPL_BC/2 * cos(a), RPL_BC/2 * sin(a), -e]) - cylinder(d = GROMMET_D, h = GROMMET_H + e); + // ── Rail clamp bolt bore (M3, centre of face plate) ────────────── + translate([0, -BASE_FACE_T - e, BASE_FACE_H/2]) + rotate([-90, 0, 0]) + cylinder(d = TNUT_BOLT_D, h = BASE_FACE_T + TNUT_H + 2*e); + + // ── M3 hex nut pocket (inside T-nut body) ──────────────────────── + translate([0, SLOT_NECK_H + 0.3, BASE_FACE_H/2]) + rotate([-90, 0, 0]) + cylinder(d = TNUT_M3_NUT_AF / cos(30), + h = TNUT_M3_NUT_H + 0.3, $fn = 6); + + // ── Column socket bore (column inserts from +Y side) ───────────── + translate([0, -BASE_FACE_T, BASE_FACE_H/2]) + rotate([-90, 0, 0]) + cylinder(d = COL_OD + 0.3, h = BASE_FACE_T + COL_SOCKET_L + e); + + // ── Column lock bolt bores (2× M4, horizontal through socket boss) ─ + // One bolt from +X, one from -X, on COL_SOCKET_L/2 depth + for (lx = [-1, 1]) + translate([lx * (COL_SOCKET_D/2 + e), COL_SOCKET_L/2, BASE_FACE_H/2]) + rotate([0, 90, 0]) + cylinder(d = M4_D, h = COL_SOCKET_D + 2*e, + center = true); + + // ── M4 nut pockets (one side of socket boss for each bolt) ──────── + for (lx = [-1, 1]) + translate([lx * (COL_SOCKET_D/2 - M4_NUT_H - 1), + COL_SOCKET_L/2, + BASE_FACE_H/2]) + rotate([0, 90, 0]) + cylinder(d = M4_NUT_AF / cos(30), + h = M4_NUT_H + 0.5, $fn = 6); + + // ── Cable exit slot (bottom of socket, cable exits downward) ────── + translate([0, COL_SOCKET_L * 0.6, BASE_FACE_H/2 - COL_SOCKET_D/2]) + cube([COL_SLOT_W, COL_SOCKET_D + e, COL_SLOT_H], center = [true, false, false]); + + // ── Lightening pockets in face plate ───────────────────────────── + translate([0, -BASE_FACE_T/2, BASE_FACE_H/2]) + cube([BASE_FACE_W - 12, BASE_FACE_T - 2, BASE_FACE_H - 16], + center = true); + } +} + +// ============================================================ +// PART 2 — ELEVATION COLUMN +// ============================================================ +// Hollow cylindrical mast (ELEV_H tall) raising the RPLIDAR scan +// plane above the chassis body for unobstructed 360° coverage. +// Inner bore routes USB cable from scanner to base exit slot. +// Bottom peg inserts into tnut_base socket; top peg inserts into +// scan_platform socket. Both ends are plain Ø(COL_OD) cylinders, +// interference-free slip fit into Ø(COL_OD+0.3) sockets. +// +// Three longitudinal ribs on outer surface add torsional stiffness +// without added diameter. Cable slot on one rib for cable retention. +// +// Print: standing upright, PETG, 5 perims, 20 % gyroid (hollow). +module column() { + rib_w = 3.0; + rib_h = 2.0; // rib protrusion from column OD + + difference() { + union() { + // ── Hollow cylinder ─────────────────────────────────────────── + cylinder(d = COL_OD, h = ELEV_H + COL_SOCKET_L); + + // ── Three stiffening ribs (120° apart) ──────────────────────── + for (ra = [0, 120, 240]) + rotate([0, 0, ra]) + translate([COL_OD/2 - e, -rib_w/2, 0]) + cube([rib_h + e, rib_w, ELEV_H + COL_SOCKET_L]); + } + + // ── Central cable bore (full length) ───────────────────────────── + translate([0, 0, -e]) + cylinder(d = COL_ID, h = ELEV_H + COL_SOCKET_L + 2*e); + + // ── Cable entry slot at column base (aligns with base exit slot) ── + translate([-COL_SLOT_W/2, COL_OD/2 - e, -e]) + cube([COL_SLOT_W, COL_ID/2 + rib_h + 2, COL_SLOT_H + 2]); + + // ── Cable exit slot at column top (USB exits to scanner) ────────── + translate([-COL_SLOT_W/2, COL_OD/2 - e, + ELEV_H + COL_SOCKET_L - COL_SLOT_H - 2]) + cube([COL_SLOT_W, COL_ID/2 + rib_h + 2, COL_SLOT_H + 2]); + + // ── Column lock flat (prevents rotation in socket) ──────────────── + // Two opposed flats at column base & top socket peg + for (peg_z = [0, ELEV_H]) { + translate([-COL_OD/2 - e, COL_OD/2 - 2.0, peg_z]) + cube([COL_OD + 2*e, 2.5, COL_SOCKET_L]); } } } -// ───────────────────────────────────────────────────────────── -// Render selector -// ───────────────────────────────────────────────────────────── -if (RENDER == "ring") { - rplidar_ring(); +// ============================================================ +// PART 3 — SCAN PLATFORM +// ============================================================ +// Disc that RPLIDAR A1 mounts to. Matches RPLIDAR A1 bolt pattern: +// 4× M3 on Ø40 mm bolt circle at 45°/135°/225°/315°. +// M3 hex nuts captured in underside pockets (blind, tool-free install). +// Column-top socket on underside receives column top peg (Ø25 slip fit). +// Motor connector slot on rear edge for JST cable exit. +// Vibe ring sits on top face between platform and RPLIDAR (separate part). +// +// Scan plane (19 mm above mount face) clears platform top by design; +// minimum platform OD = RPL_CLEAR_D (82 mm) leaves scan plane open. +// +// Print: disc face down, PETG, 5 perims, 40 % gyroid. +module scan_platform() { + difference() { + union() { + // ── Platform disc ───────────────────────────────────────────── + cylinder(d = PLAT_OD, h = PLAT_T); -} else if (RENDER == "assembly") { - // Platform stub - color("Silver", 0.5) - difference() { - cylinder(d = 90, h = 8); - translate([0, 0, -e]) cylinder(d = 25.4, h = 8 + 2*e); + // ── Column socket boss (underside, -Z) ──────────────────────── + translate([0, 0, -PLAT_SOCKET_L]) + cylinder(d = COL_SOCKET_D, h = PLAT_SOCKET_L + e); } - // Ring floating 8 mm above (grommet gap) - color("SkyBlue", 0.9) - translate([0, 0, 8 + 8]) - rplidar_ring(); + + // ── Column socket bore (column top peg inserts from below) ──────── + translate([0, 0, -PLAT_SOCKET_L - e]) + cylinder(d = PLAT_SOCKET_D, h = PLAT_SOCKET_L + e + 1); + + // ── Column lock bores (2× M4 through socket boss) ───────────────── + for (lx = [-1, 1]) + translate([lx * (COL_SOCKET_D/2 + e), 0, -PLAT_SOCKET_L/2]) + rotate([0, 90, 0]) + cylinder(d = M4_D, h = COL_SOCKET_D + 2*e, center = true); + + // ── M4 nut pockets (one side socket boss) ───────────────────────── + translate([COL_SOCKET_D/2 - M4_NUT_H - 1, 0, -PLAT_SOCKET_L/2]) + rotate([0, 90, 0]) + cylinder(d = M4_NUT_AF / cos(30), h = M4_NUT_H + 0.5, + $fn = 6); + + // ── 4× RPLIDAR mounting bolt holes (M3, Ø40 mm BC at 45°) ──────── + for (a = [45, 135, 225, 315]) + translate([RPL_BC_D/2 * cos(a), + RPL_BC_D/2 * sin(a), -e]) + cylinder(d = RPL_BOLT_D, h = PLAT_T + 2*e); + + // ── M3 hex nut pockets on underside (captured, tool-free) ───────── + for (a = [45, 135, 225, 315]) + translate([RPL_BC_D/2 * cos(a), + RPL_BC_D/2 * sin(a), -e]) + cylinder(d = M3_NUT_AF / cos(30), + h = M3_NUT_H + 0.5, $fn = 6); + + // ── Motor connector slot (JST rear centreline, 10×6 mm) ────────── + translate([0, PLAT_OD/2 - 8, -e]) + cube([10, 10, PLAT_T + 2*e], center = [true, false, false]); + + // ── USB connector slot (micro-USB, right-rear, 12×6 mm) ────────── + translate([PLAT_OD/4, PLAT_OD/2 - 8, -e]) + cube([12, 10, PLAT_T + 2*e], center = [true, false, false]); + + // ── Lightening pockets (between bolt holes) ──────────────────────── + for (a = [0, 90, 180, 270]) + translate([(RPL_BC_D/2 + 10) * cos(a), + (RPL_BC_D/2 + 10) * sin(a), -e]) + cylinder(d = 8, h = PLAT_T + 2*e); + + // ── Central cable bore (USB from scanner routes down column) ────── + translate([0, 0, -e]) + cylinder(d = COL_ID - 2, h = PLAT_T + 2*e); + } +} + +// ============================================================ +// PART 4 — VIBRATION ISOLATION RING +// ============================================================ +// Flat ring sits between scan_platform top face and RPLIDAR bottom. +// Anti-vibration isolation via 4× M3 silicone FC-style grommets +// (Ø6 mm silicone, M3 bore — same type used on flight controllers). +// +// Bolt stack (bottom → top): +// M3 × 30 SHCS → platform (countersunk) → grommet (Ø7 seat) → +// ring (4 mm) → RPLIDAR threaded boss (~6 mm engagement) +// +// Grommet seats are recessed 1.5 mm into ring bottom face so grommets +// are captured and self-locating. Ring top face is flat for RPLIDAR. +// +// Print: flat on bed, PETG or TPU 95A, 3 perims, 20 % infill. +// TPU 95A provides additional compliance in axial direction. +module vibe_ring() { + difference() { + // ── Ring body ──────────────────────────────────────────────────── + cylinder(d = RING_OD, h = RING_H); + + // ── Central bore (cable / connector access) ─────────────────────── + translate([0, 0, -e]) + cylinder(d = RING_ID, h = RING_H + 2*e); + + // ── 4× M3 clearance bores on Ø40 mm bolt circle ─────────────────── + for (a = [45, 135, 225, 315]) + translate([RPL_BC_D/2 * cos(a), + RPL_BC_D/2 * sin(a), -e]) + cylinder(d = RPL_BOLT_D, h = RING_H + 2*e); + + // ── Grommet seating recesses (bottom face, Ø7 mm × 1.5 mm deep) ── + for (a = [45, 135, 225, 315]) + translate([RPL_BC_D/2 * cos(a), + RPL_BC_D/2 * sin(a), -e]) + cylinder(d = GROMMET_D, h = GROMMET_RECESS + e); + + // ── Motor connector notch (rear centreline, passes through ring) ── + translate([0, RING_OD/2 - 6, -e]) + cube([10, 8, RING_H + 2*e], center = [true, false, false]); + + // ── Lightening arcs ─────────────────────────────────────────────── + for (a = [0, 90, 180, 270]) + translate([(RPL_BC_D/2 + 9) * cos(a), + (RPL_BC_D/2 + 9) * sin(a), -e]) + cylinder(d = 7, h = RING_H + 2*e); + } +} + +// ============================================================ +// PART 5 — CABLE GUIDE CLIP +// ============================================================ +// Snap-on C-clip that presses onto column ribs to retain USB cable +// along column exterior. Cable sits in a semicircular channel; +// snap tongue grips the rib. No fasteners — push-fit on rib. +// Print multiples: one every ~30 mm along column for clean routing. +// +// Print: clip-opening face down, PETG, 3 perims, 20 % infill. +// Orientation matters — clip opening (-Y face) must face down for bridging. +module cable_guide() { + snap_t = 1.8; // snap tongue thickness (springy PETG) + snap_oc = GUIDE_CABLE_D + 2*GUIDE_T; // channel outer cylinder OD + body_h = GUIDE_BODY_H; + + difference() { + union() { + // ── Clip body (flat plate on column face) ───────────────────── + translate([-GUIDE_BODY_W/2, 0, 0]) + cube([GUIDE_BODY_W, GUIDE_T, body_h]); + + // ── Cable channel (C-shape, opens toward +Y) ────────────────── + translate([0, GUIDE_T + snap_oc/2, body_h/2]) + rotate([0, 90, 0]) + difference() { + cylinder(d = snap_oc, h = GUIDE_BODY_W, + center = true); + cylinder(d = GUIDE_CABLE_D, h = GUIDE_BODY_W + 2*e, + center = true); + // Open front slot for cable insertion + translate([0, snap_oc/2 + e, 0]) + cube([GUIDE_CABLE_D * 0.85, + snap_oc + 2*e, + GUIDE_BODY_W + 2*e], center = true); + } + + // ── Snap-fit tongue (grips column rib, -Y side of body) ─────── + // Two flexible tabs that straddle column rib + for (tx = [-GUIDE_BODY_W/2 + 2, GUIDE_BODY_W/2 - 2 - snap_t]) + translate([tx, -4, 0]) + cube([snap_t, 4 + GUIDE_T, body_h]); + + // Snap barbs (slight overhang engages rib back edge) + for (tx = [-GUIDE_BODY_W/2 + 2, GUIDE_BODY_W/2 - 2 - snap_t]) + translate([tx + snap_t/2, -4, body_h/2]) + rotate([0, 90, 0]) + cylinder(d = 2, h = snap_t, center = true); + } + + // ── Rib slot (column rib passes through clip body) ───────────────── + translate([0, -2, body_h/2]) + cube([3.5, GUIDE_T + 4 + e, body_h - 4], center = true); + } }