// Circunference
c = 100;
// Number of marks
marks = 10;
// Wheel tickness
thickness = 2;
// Hub tickness
max_thickness = 3;
// Axle radius
axle_r = 3;

r = c/PI/2;

difference() {
    union() {
        cylinder(r=r, h=thickness);
        cylinder(r=axle_r*2, h=max_thickness);
    }
    for (i = [0:marks]) {
        rotate([0, 0, i*360/marks]) translate([r*0.75, -0.5, thickness-1]) cube([r, 1, 2]);
    }
    translate([r/2, -0.5, thickness-1]) cube([r, 1, 2]);
    cylinder(r=axle_r, h=max_thickness*2+1, center=true, $fn=30);
}