e = 0.1;

$fn = 60;

module motor() {
  translate([0, 0, 18+21])
    cylinder(3, d=6.5, d=6.5);
  translate([0, 0, 18])
    cylinder(18, d=23.5, d=23.5);
  cylinder(21, d=25, d=25);
}

module wheel() {
  spokes = 5;
  r = 20; // Wheel radius
  w = 2;  // Spoke radius
  rt = 4; // Rim thickness

  module spokes() {
    rotate([0, 90, 0])
      for (i = [0:360/spokes:360]) {
	rotate([i, 0, 0])
	  cylinder(r, w, w);
      }
  }

  module hub() {
    translate([0, 0, -w])
      cylinder(w*2, d=19, d=19);
  }

  module slot(o) {
    t = 1;
    translate([0, 0, o])
    difference() {
      translate([0, 0, -w])
	linear_extrude(t)
	circle(r+rt+e);
      translate([0, 0, -w-e])
	linear_extrude(t+2*e)
	circle(r+rt-t);
    }
  }
  
  module rim() {
    difference() {
      translate([0, 0, -w])
	linear_extrude(w*2)
	circle(r+rt);
      translate([0, 0, -w-e])
	linear_extrude(w*2+2*e)
	circle(r);
      slot((rt-1)/2);
    }
  }

  module cap() {
    v = 6;
    cylinder(v, 5, 5);
    translate([0, 0, v])
      sphere(5);
  }

  translate([0, 0, w])
    union() {
    //        spokes();
	hub();
	//	rim();
	cap();
  }
}

module shaft() {
  h = 9.8+3;
  r = 2 + 0.4;

  difference() {
    translate([0, 0, -2])
      cylinder(h, r, r);
    translate([2*2-2.5, -2*r, -2-e])
      cube([4, 4*r, h+e*2]);
  }
  translate([0, 0, -e])
    cylinder(0.6, r+1, r+1);
}

difference() {
  wheel();
  shaft();
}