It took an entire day to adapt this to work on my mill. I had to create a custom mounting plate, a shaft bushing to adapt the inside diameter of the bearing to the diameter of my mills handle shaft, then I had to file a key slot in the handle shaft to fit the keyway and key for this unit to attach to the shaft. I also had to drill and tap the end of my handle shaft to bolt on the unit as my handle shaft was of insufficient length. Had to drill mounting holes for the stop switch bracket as well. If it all just slid onto a 5/8" diameter shaft as a unit, it would be a lot easier to install. My old handle assembly would not connect to the unit, so I can only turn it by hand from the other end.