// Wheel radius (approximated)
r = 20;
// Number of pins
pins = 23;
// Wheel tickness
thickness = 2;
// Hub tickness
max_thickness = 3;
// Axle radius
axle_r = 3;

difference() {
    union() {
        for (i = [0:pins]) {
            rotate([0, 0, i*360/pins]) translate([0, -0.5, 0]) cube([r, 1, 2]);
        }
        cylinder(r=r*0.9, h=thickness);
        cylinder(r=axle_r*2, h=max_thickness);
    }
    cylinder(r=axle_r, h=max_thickness*2+1, center=true, $fn=30);
}