pulley-elliptical.scad

   1 infty = 100;
   2 eps = 0.01;
   3
   4 wall = 0.6;             // minimum wall
   5 d_x = 25;               // inner diameter in the X axis
   6 y_scale = 0.5;          // scale y/x
   7 height = 2.5;           // height of the rim
   8
   9 slot_w = 1.5;
  10 side_hole_d = 2.0;
  11
  12 module half(d_x, y_scale, height) {
  13         hull($fn = 128) {
  14                 scale([1, (d_x*y_scale+height)/(d_x+height), 1])
  15                         cylinder(r = d_x/2 + height/2, h = eps);
  16                 translate([0, 0, height/2])
  17                         scale([1, y_scale, 1])
  18                         cylinder(r = d_x/2, h = eps);
  19         }
  20 }
  21
  22 module pulley(d_x, y_scale, height, center_hole_d) {
  23         difference() {
  24                 union() {
  25                         half(d_x, y_scale, height);
  26                         translate([0, 0, height]) scale([1, 1, -1])
  27                                 half(d_x, y_scale, height);
  28                 }
  29                 translate([0, 0, -eps])
  30                         cylinder(r = center_hole_d/2, h = height + 2*eps);
  31                 translate([-slot_w/2, d_x*y_scale/2, -eps])
  32                         cube([slot_w, height, height + 2*eps]);
  33 //              translate([0, center_hole_d/2 + (d_x*y_scale/2-center_hole_d/2)/2, -eps])
  34 //                      cylinder(r = side_hole_d/2, h = height + 2*eps);
  35         }
  36 }
  37
  38 pulley(d_x = 6, y_scale = 2.5, height=2.5, center_hole_d = 2.5);
  39
  40 translate([0, 20, 0])
  41 pulley(d_x = 35, y_scale = 0.4, height=2.5, center_hole_d = 8);
  42