140 lines
5.6 KiB
OpenSCAD
140 lines
5.6 KiB
OpenSCAD
// Fischertechnik compatible gears.
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// Makes use of the library
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// https://github.com/chrisspen/gears.git
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// instead of the MCAD "Parametric Involute Bevel and Spur Gears" library
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// which has really a lot of parameters and looks quite complicate.
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//
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// The Fischertechnik technical background is described here:
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// https://www.ftcommunity.de/ftpedia/2011/2011-2/ftpedia-2011-2.pdf
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// page 30 ff; // Zahnräder und Übersetzungen (Teil 1)
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// https://www.ftcommunity.de/ftpedia/2011/2011-3/ftpedia-2011-3.pdf
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// page 30 ff; // Zahnräder und Übersetzungen (Teil 2)
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// https://www.ftcommunity.de/ftpedia/2012/2012-1/ftpedia-2012-1.pdf
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// page 12 ff; // Zahnräder und Übersetzungen (Teil 3)
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//
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// Fischertechnik uses two diffferent modules which can be set in the configurator:
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// m = 1.5 for the gears with the large teeth and
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// m = 0.5 for the gears with the small teeth.
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// and also a fixed number of teeth:
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// 10, 15, 20, 30, 40
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// Feel free to extend both of them as needed.
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//
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/* [Gear type] */
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// a normal gear or two gears stacked on each other
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type = 0; // [0:none, 1:normal, 2:stacked]
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/* [Gear options] */
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// Type of gear, defined by modulus
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modulus_1 = 1.5; // [0.5:small gears, 1.5:big gears]
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// The number of teeth of the bigger gear
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teeth_1 = 20; // [10, 15, 20, 30, 40]
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// Only if stacked: the number of teeth of the smaller gear
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teeth_2 = 10; // [10, 15, 20, 30, 40]
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// The height of a single gear
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height_1 = 5;
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// Is the gear optimized by a cutout?
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is_optimized = 0; // [0:no, 1:yes]
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// Do we have a round axis or a clip axis?
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has_clip_axle = 0; // [0:no, 1:yes]
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/* [Hidden] */
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// **********************
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// ** Static Settings: **
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// **********************
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include<ft_util.scad>
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include<gears.scad>
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$fn=50;
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// Depends on the printer and the ft parts.
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// For me this seems to work best:
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hole_diameter = 4.32;
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// --------------------------------------------------------------------
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// A module to calculate an ft compatible gear.
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//
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// The used gears library does some weird optimizations to reduce
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// material and weight of the gear: in addition to cutting out part
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// of the inner circle with a small height it also cuts out some holes.
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// We just want the inner circle cutout, but deeper and without the
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// additional holes.
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// In addition we have the option to get a clip axle instead of
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// a normal hole for a standard axle.
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// This gears are a bit different than the original gears because
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// the top of the original teeth is a bit smaller than the gear
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// itsself. The replicas have the same width of the teeth at the
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// top and the bottom.
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// --------------------------------------------------------------------
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module normalgear(modulus=1.5, teeth=20, height=5, hole=4.25, clipaxle=false, optimize=true) {
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// adjust?
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inner_cylinder_radius = 6.75 / 2;
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clip_axle_length = 7.5;
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clip_axle_thickness = 2.7;
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// calculate the approx. radius of the cut out
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r1 = (teeth * modulus / 2) - (modulus >= 1 ? 2 * modulus : 1.5);
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if (optimize == 1) {
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difference () {
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// for ease of use we will move the gear to the center position
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translate([0,0,height/2])
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rotate([0,180,0])
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spur_gear (modulus, teeth, height, hole, optimized=false);
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// leave 1.5 mm of the gear and cut out the rest
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translate([0,0,1.5])
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cylinder(h = height, r = r1, center = true );
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}
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// add an inner cylinder for the axle and subtract the hole or
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// clip axle hidden by the just added inner cylinder
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if (clipaxle == 1) {
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difference() {
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cylinder(h = height, r = inner_cylinder_radius, center = true );
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clip_axle_hole(length = clip_axle_length, diameter = hole, thickness = clip_axle_thickness);
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}
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}
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else {
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difference() {
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cylinder(h = height, r = inner_cylinder_radius, center = true );
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cylinder(h = height + MANIFOLD_CORRECTION, d = hole, center = true );
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}
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}
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}
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else {
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// A solid gear is much simpler and also needs only the clip axle
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// to be painted if required
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translate([0,0,height/2])
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rotate([0,180,0])
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spur_gear (modulus, teeth, height, hole, optimized=false);
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if (clipaxle == 1) {
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difference() {
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// the radius could be smaller, but so what ...
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cylinder(h = height, r = inner_cylinder_radius, center = true );
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clip_axle_hole(length = clip_axle_length, diameter = hole, thickness = clip_axle_thickness);
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}
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}
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}
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}
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// --------------------------------------------------------------------
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// This is no Fischertechnik part. It is here just for convinience.
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// Build two gears in a line. No optimization because they are stacked
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// and no clip axle hole: the hole is too long for it (max 7.5 mm with
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// real length of 5 mm, the rest is for the cone of the clip axle).
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// --------------------------------------------------------------------
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module doublegear(modulus=1.5, teeth1=20, teeth2=10, height=5, hole=4.2) {
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normalgear (modulus, teeth1, height, hole, clipaxle=false, optimize = false);
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translate([0,0,height-0.01])
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normalgear (modulus, teeth2, height, hole, clipaxle=false, optimize = false);
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}
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// ********************
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// ** Build section: **
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// ********************
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module main() {
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if (type == 1){
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normalgear (modulus=modulus_1, teeth=teeth_1, height=height_1, hole=hole_diameter, clipaxle=has_clip_axle, optimize=is_optimized);
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}
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else if (type == 2) {
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doublegear (modulus=modulus_1, teeth1=teeth_1, teeth2=teeth_2, height_1, hole_diameter);
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}
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}
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main(); |