Quote Originally Posted by Toolmaker51 View Post
Main problems with Vee-thread, combinations of diameter and pitch won't be very rapid lifting action, and Vee's have little tolerance for dirt and chips. I'm still a hold-out for ACME, which translate torque to movement quickly compared to a multi-start Vee.
Most round column drill presses use a rack and pinion. Bottom edge of rack is mitered, it rides in a chamfered ring encircling the column. Below that ring is another to take thrust. All it takes is a small handle, spins a worm/ pinion combination to climb or descend the rack. And when you let go it remains in that position, but table can still rotate about the column.

A couple Martin or Browning gears, matching rack, aluminum billet housing and a couple oil-lite bushings, and two stubs of thick wall pipe; if I insisted on mechanical positioning.
Aforementioned notched lever, stripper bolt, some chain and and a slug of rod stock for weight. Far simpler and equally effective.

How about a dedicated winding motor; provided 12v DC, attach a auto window or power seat motor. Substantial torque, controllable [single speed] RPM, hypoid-geared, reversible; need I continue?
I do have a length of ACME threaded rod. I played with it on the end of a small electric screwdriver and it does appear to work. It would work a lot better if my ACME nut was in a pinion gear so the screwdriver was horizontal.

My RF-30 mill/drill has the arrangement you describe and it works well enough. Once I changed to CNC, I have not needed to move the head much.

I forgot that I have a window motor from a car. That shows a lot of promise! It has a lot of torque so would add a mechanical fuse to the linkage to protect the drill press.

Thanks,

Rick