Motorized rotary table

[tonyfoale]

I realize (realise) you are just drilling the holes, Tony but seeing your photo of the timing belt hub

You have lost me here.
Firstly, Drilling what holes?
Secondly, I think that you are confusing a clutch hub with a timing belt pulley. Those teeth are convex shape whereas pully teeth are concave. As in the Haas video I did use a form tool for that. I modified my T&C grinder Homemade Tool & Cutter grinder (with a difference). to be able to make the tool. The Haas video formed the teeth by slotting whereas I did it by milling.

Just to be clear, this work was done on a mill not a lathe.

The tooth shape had to precisely fit an off the shelf clutch plate as shown here. It was a tricky job because there was no easy reference off the tool from which to set the DOC. I was unsure how good a job I could make of it so I made a test example using 1/4" plate, so as not to risk the real thing.

Test piece. Click for full size.

Clutch plate on real piece.

Assembled clutch pack.