oring_diameter=15;
oring_thickness=3;
drill=3.2;
wheel_width=6;

wheel_diameter=oring_diameter+oring_thickness;


difference() {
  cylinder(r=wheel_diameter/2, h=wheel_width,$fn=100,center=true);

  rotate_extrude(convexity = 10,$fn=100)
  translate([oring_diameter/2+oring_thickness/2, 0, 0])
  circle(r=oring_thickness/2,$fn=50);

  cylinder(r=drill/2,h=20,center=true,$fn=50);
}


*difference() {
  cylinder(r=13/2, h=thick,$fn=50,center=true);
  cylinder(r=drill/2, h=20, $fn=50, center=true);
}