Very interesting setup with the step collet and bonze support. I have a pretty good idea about what you can't see, but details would be interesting. For example, is the support live or stationary? I am assuming you achieved a good result?
@RailMix The brass cylinder is center drilled on the right and can spin on the tailstock center. It's not really visible but there is a small nib that is pressing on the metal in the center of the driver, to help hold it in the collet. There is very little for the collet to grab onto, so this helps prevent the driver from popping out while the tool is working on it. You wouldn't want to hold the part by the center hub, as the pressure from the cutting would probably destroy the plastic center. Hope this helps