scad-library-mcad

name	scad-library-mcad
description	This skill should be used when generating OpenSCAD with MCAD, especially involute gears, bevel gears, motors, servos, regular shapes, nuts, bolts, and established mechanical primitives bundled with OpenSCAD.
triggers	["use mcad","involute gear","bevel gear","mcad helpers"]

SCAD Library MCAD Skill

Use MCAD when the runtime prompt lists MCAD and the requested part needs established mechanical primitives, especially gears.

Imports

Use the narrowest MCAD file needed:

use <MCAD/involute_gears.scad>

Use include <MCAD/units.scad> only when constants from the file are required. Prefer use for module-only imports because it avoids top-level demonstration geometry.

Best Uses

• Use gear() from MCAD/involute_gears.scad for spur gears when exact involute tooth geometry matters.
• Use bevel_gear() or bevel_gear_pair() for bevel gears when the request explicitly asks for them.
• Use MCAD motor/servo helpers only when exact module names and signatures are known.
• Use MCAD regular shapes when they simplify geometry without reducing editability.

Generation Pattern

Expose gear controls as top-level parameters and call MCAD inside a wrapper module:

use <MCAD/involute_gears.scad>

/* [Gear] */
teeth = 24;            // min: 8 max: 160 step: 1
circular_pitch = 220;  // min: 80 max: 600 step: 5
pressure_angle = 20;   // min: 14.5 max: 25 step: 0.5
gear_thickness = 8;    // min: 2 max: 40 step: 0.5
bore_diameter = 5;     // min: 1 max: 40 step: 0.5

module printable_gear() {
  gear(
    number_of_teeth=teeth,
    circular_pitch=circular_pitch,
    pressure_angle=pressure_angle,
    bore_diameter=bore_diameter,
    gear_thickness=gear_thickness,
    rim_thickness=gear_thickness,
    hub_thickness=gear_thickness,
    flat=true
  );
}

printable_gear();

Quality Rules

• For gears, expose teeth count, pitch, pressure angle, bore diameter, and thickness.
• Keep pressure angle default at 20 degrees unless specified.
• Add bore and hub features intentionally; do not leave a solid gear when an axle hole is likely needed.
• Prefer MCAD gear modules over hand-drawn rectangular tooth approximations.

Avoid

• Do not use broad include statements when use is sufficient.
• Do not invent MCAD module names.
• Do not copy MCAD source into generated SCAD.