Robot parts. Idler pulleys being modified to accept 22mm skate bearings. Trochoidal path was used to cut the half inch deep groove around the bearing hub which decrease the weight by 5 oz. per idler. Trochoidal path used a 0.375" end mill , 0.5" DOC, 3200 RPM, 25% step over, 40 IPM, 0.002" IPT. Ramp in was 3 degrees and also used a trochoidal path which worked well.