Here is my mandrel which I will use to slow down my wood working Rockwell drill to make it more useful and easy to use in drilling metal at lower speed and with more torque. I poured aluminum that I heated in an old pottery kiln directly into a soup can. Then a buddy Rob, in Edmonton machined the flats and drilled and tapped the bottom for bolts. He also made pockets for the 3/4" I.D. bearings and fastened the large washers as retainers. During part of this he was giving me an excellent tutorial on how to setup and run the Haas CNC mill. Naturally I immediately forgot a bunch.