I just finished this project. It is of course a small drilling and milling head with a rack and pinion quill. The motor is from a mini lathe.
The housing was taken from an old cheap import drill press. I cut it down and boxed it in. Then indicated the quill dead level and flycut the mounting surface.
It originally had a mt2 tapered spindle.
I made a new spindle out of some 1144 stress proof. It is a 3/8" end mill holder type spindle.
The spindle has 1 bearing at each end of the quill cartridge and I added a bearing preload nut. The splined drive has 2 bearings.
I built this unit primarily for my HBM/lathe machine.