I have put a few pictures of the Quill Feed Drive I made for my Warco VMC mill using a Nema 23 Stepper with a 4.25 to 1 gearbox in my album. It is loosely based on the Peter Rawlinson unit published in MEW No76.
I recently had to bore several holes for the cnc machine I am building and I got very bored having to keep turning the feed wheel by hand so I came up with this unit which works very well. You can still use the handwheel in manual mode if required.
On disassembling the worm shaft I decided to do away with the thrust bearings and use ball races instead. The thrust is not that high so I don't think there will be a problem. This meant I had to make a new housing which was made out of steel. I incorporated a preload spacer between the bearings so I could do away with the 2 lock nuts and just use 1. I drilled and tapped the lock nut for a small grub screw with a brass cap so as not to damage the thread.
The motor plate is 10mm aluminium. The motor is a small nema 23 with a 4.25:1 gearbox with a further 2:1 reduction by toothed belt and HTD3 pulleys. I made the ends by turning a 74mm od ally ring from some cored ally bar I had and then cut it in half. The sides are made from 6mm ally plate.
The large pulley fits into a recess on the handwheel and because the keyway on the shaft is not long enough I transmit the drive via a 6mm drive pin from the handwheel to the pulley.
I have been controlling it from the main control box which controls all the feed motors on the mill ( I am using the Z axis controller) but I am now going to use an arduino to control it. A fellow forum member has kindly sent me his program for the arduino so I can control it with a separate controller.
Hope it may be of interest to someone.