clean up gear code

This commit is contained in:
Stewart Allen 2024-07-18 20:32:38 -06:00
commit 9407d50e9a

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@ -744,6 +744,7 @@ mesh.tool = class MeshTool {
// Adapted from: Public Domain Parametric Involute Spur Gear by Leemon Baird, 2011, Leemon@Leemon.com http://www.thingiverse.com/thing:5505
// see also http://grabcad.com/questions/tutorial-how-to-model-involute-gears-in-solidworks-and-show-design-intent
// const pitch_radius = (numTeeth * module) / 2;
const pi = Math.PI;
// degrees to radians
@ -761,6 +762,7 @@ mesh.tool = class MeshTool {
// radius a fraction f up the curved side of the tooth
function q7(f, r, b, r2, t, s) { return q6(b, s, t, (1 - f) * Math.max(b, r) + f * r2); }
// lerp q7 0..1 with a given # steps
function qf(steps, r, b, r2, t, s) {
let res = [];
let step = 1/steps;
@ -783,41 +785,37 @@ mesh.tool = class MeshTool {
return answer;
}
// gear parameter setup
let mm_per_tooth = module * pi; // mm size of one gear tooth
let clearance = 0.1; // freedom between two gear centers
let backlash = 0.1; // freedom between two gear contact points
let pressure_angle = degrees_to_radians(pressureAngle);
let gear = [];
// involute gear maker
function build_gear(number_of_teeth) {
let p = mm_per_tooth * number_of_teeth / pi / 2; // radius of pitch circle
{
let p = mm_per_tooth * numTeeth / pi / 2; // radius of pitch circle
let c = p + mm_per_tooth / pi - clearance; // radius of outer circle
let b = p * Math.cos(pressure_angle); // radius of base circle
let r = p - (c - p) - clearance; // radius of root circle
let t = mm_per_tooth / 2 - backlash / 2; // tooth thickness at pitch circle
let k = -iang(b, p) - t / 2 / p; // angle where involute meets base circle on side of tooth
let points = [ // [x,y] points for a single gear tooth
polar(r, -pi / number_of_teeth),
polar(r, r < b ? k : -pi / number_of_teeth),
polar(r, -pi / numTeeth),
polar(r, r < b ? k : -pi / numTeeth),
...qf(10, r, b, c, k, 1),
...qf(10, r, b, c, k, -1).reverse(),
polar(r, r < b ? -k : pi / number_of_teeth),
// polar(r, 3.142 / number_of_teeth)
polar(r, r < b ? -k : pi / numTeeth),
// polar(r, 3.142 / numTeeth) // omit b/c overlaps start when rotated
];
let gear = [];
// create all gear teeth by rotating the first tooth
for (var i = 0; i < number_of_teeth; i++) {
gear.appendAll(rotate(points, -i * 2 * pi / number_of_teeth));
for (var i = 0; i < numTeeth; i++) {
gear.appendAll(rotate(points, -i * 2 * pi / numTeeth));
}
return gear; // returns an array of [x,y] points
}
// gear parameter setup
let mm_per_tooth = 2 * module * pi; // mm size of one gear tooth
let clearance = 0; // freedom between two gear centers
let backlash = 0; // freedom between two gear contact points
let pressure_angle = degrees_to_radians(pressureAngle);
console.log({ mm_per_tooth });
return build_gear(numTeeth);
return gear;
}
};