William Miceli
139 lines
5.7 KiB
OpenSCAD
139 lines
5.7 KiB
OpenSCAD
/* ================================================================
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Cable Grommet for Sheet Metal — TPU Print
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================================================================
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Protects cable insulation from sharp drilled-hole edges.
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The grommet body fits inside the drilled hole while the two
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flanges seat flush against each face of the sheet metal,
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creating a smooth, rounded channel for the cable.
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INSTALLATION:
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Squeeze / fold the grommet (TPU flexibility makes this easy)
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and press it through the hole until both flanges snap flat
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against the sheet metal on each side.
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TIPS FOR TPU PRINTING:
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- 3–4 perimeters / walls for durability
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- 20–40% infill
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- No supports needed (prints flat on bottom flange)
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- Slow print speed recommended (≤ 30 mm/s) for clean bridges
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================================================================ */
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// ================================================================
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// USER PARAMETERS — edit these to match your application
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// ================================================================
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// Diameter of the hole drilled in the sheet metal (mm)
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hole_diameter = 13;
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// Thickness of the sheet metal (mm)
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sheet_thickness = 1;
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// Thickness of the grommet body wall (mm)
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// This directly sets how large the cable hole is:
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// cable hole = hole_diameter - 2 x wall_thickness
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// Decrease to widen the cable hole; increase to narrow it.
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wall_thickness = 2.0;
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// How far each flange lip extends beyond the hole edge (mm)
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// Larger value = more grip on the sheet metal.
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flange_lips_overhang = 2.0;
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// Thickness of each flange lip (mm)
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flange_lips_thickness = 2.0;
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// Chamfer radius at each cable entry/exit (mm)
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// This is the most important feature for insulation protection.
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// The chamfer creates a smooth funnel so the cable never contacts
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// a sharp edge even under vibration or flex.
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cable_chamfer = 0;
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// ================================================================
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// RENDERING QUALITY
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// ================================================================
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$fn = 128;
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// ================================================================
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// DERIVED VALUES (do not edit below this line)
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// ================================================================
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_body_d = hole_diameter;
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_flange_d = hole_diameter + (2 * flange_lips_overhang);
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_cable_d = _body_d - (2 * wall_thickness);
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_body_len = sheet_thickness;
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_total_h = (2 * flange_lips_thickness) + _body_len;
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// Sanity-check echoes (visible in OpenSCAD console)
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echo(str("=== Cable Grommet Summary ==="));
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echo(str(" Body outer diameter : ", _body_d, " mm"));
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echo(str(" Flange diameter : ", _flange_d, " mm"));
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echo(str(" Cable hole diameter : ", _cable_d, " mm"));
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echo(str(" Wall thickness : ", wall_thickness, " mm"));
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echo(str(" Total height : ", _total_h, " mm"));
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if (wall_thickness < 1.5) {
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echo(" WARNING: Wall thickness is thin — consider increasing wall_thickness.");
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}
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if (_cable_d <= 0) {
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echo(" ERROR: wall_thickness is too large — cable hole is zero or negative.");
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}
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if (cable_chamfer > flange_lips_thickness) {
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echo(" WARNING: cable_chamfer is larger than flange_lips_thickness — chamfer will be clipped.");
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}
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// ================================================================
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// MODULE
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// ================================================================
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module grommet() {
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difference() {
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// ── OUTER SHELL ──────────────────────────────────────────
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union() {
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// Bottom flange
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// Wider at the sheet metal face, narrower at the outer (free) face.
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cylinder(d1 = _flange_d - 1.5, d2 = _flange_d, h = flange_lips_thickness);
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// Body — the section that lives inside the drilled hole
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translate([0, 0, flange_lips_thickness])
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cylinder(d = _body_d, h = _body_len);
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// Top flange
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// Wider at the sheet metal face, narrower at the outer (free) face.
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translate([0, 0, flange_lips_thickness + _body_len])
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cylinder(d1 = _flange_d, d2 = _flange_d - 1.5, h = flange_lips_thickness);
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}
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// ── CABLE BORE ────────────────────────────────────────────
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// Straight through-hole for the cable
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translate([0, 0, -0.01])
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cylinder(d = _cable_d, h = _total_h + 0.02);
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// ── BOTTOM ENTRY CHAMFER ──────────────────────────────────
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// Smooth funnel on the side the cable enters from.
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translate([0, 0, -0.01])
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cylinder(
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d1 = _cable_d + (2 * cable_chamfer),
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d2 = _cable_d,
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h = cable_chamfer + 0.01
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);
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// ── TOP EXIT CHAMFER ──────────────────────────────────────
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// Mirror chamfer on the other side — equally important when
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// the cable flexes back toward the sheet metal.
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translate([0, 0, _total_h - cable_chamfer + 0.01])
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cylinder(
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d1 = _cable_d,
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d2 = _cable_d + (2 * cable_chamfer),
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h = cable_chamfer + 0.01
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);
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}
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}
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// ================================================================
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// RENDER
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// ================================================================
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grommet();
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