Posted by Robert Atkinson 2 on 20/01/2020 07:25:40:
My plan for this is to take the motor and gearbox out of an old cordless drill. I've kept an old Bosch that the NiCad batteries died years ago fir just this purpose. Some need the case to hold parts together but this can be solved at various levels of neatness (hacking the handle off to machining a shiny new housing. It will run off a 12V supply with speed control modified to a rotary knob.
Robert G8RPI.
Problem with this approach is that most cordless drills, and generally all the lower costs ones, have a rather low high speed rpm top end – typically 1200 to 1500rpm and that tends to be a bit low for the smaller drill sizes, below 3mm perhaps. Also, the front bearing is not the greatest, and neither is the chuck, all giving rather poor runout performance.