What motor do I use for raising a drill press table?

[ARC-170]

I have a design idea for a table raising mechanism for my Craftsman drill press. How would I know what type of motor to buy? Specifically, what torque spec am I looking for? I'm not sure how to go about calculating it. Here is the design idea:


The motor is mounted at the bottom (haven't figured that out yet, so it's not in the sketch) and is stationary. It has a threaded rod (1/2" diameter, maybe) attached that spins. There is a fabricated bracket attached to the table that has a threaded hole that the rod rides in, lowering and raising the table as the shaft spins.
I'll run a switch from the motor to either a foot pedal or rocker switch, I haven't decided yet. I want to figure out what motor to use.

I was going to use a drill, but a motor mounted on the drill press seems like a better design. A 5A drill has about 3/4 HP or so, which I think is about 412 lb/ft of torque? Do I have that right? Is that enough?

The table weighs about 30-50 lbs and needs lubrication on the column to move better, but it does slide up and down with some effort.

McMaster-Carr has motors, but the specs are all over the place, as are the prices. I'd like some help figuring out what I need. Thanks!

 

[benmychree]

This design does not allow the table to be swung aside for long workpieces

 

[itsme_Bernie]

Is there a way to hook up a milling machine power feed?
Otherwise you will need an angle drive with gear reduction.
You may also want to try to pull or push the table from the front, at least some of the weight, to keep it from jamming
Bernie

 

[Jim F]

If the motor was mounted to a plate clamped around the column so it rotated with the table it might work.
Or a winch set-up from the top.

 

[hman]

OK, just spitballing here ...
First off, decide how fast you want the table to move. If you have a relatively slow motor, use a coarse (like 1/2-13) threaded rod. If the motor is fast, you might go with fine thread (like 1/2-20).
Second, you'll probably want to support the bottom of the threaded rod directly against something solid, rather than going through the motor and making the motor bearings hold the weight. Use a timing belt, bicycle chain, or gears to couple the motor to the rod. Or maybe mount the motor to the top of the rod.
Finally, find a DC gearmotor with appropriate speed and power. There's such a variety out there that I doubt I could be of much help.

If this were several years ago, I'd have suggested going to a "big dish" satellite TV installer to beg or buy a used dish positioner motor. But they're kinda hard to find nowadays. They had a useful speed, lots of power, and a very interesting feature ... internal limit switches! Here's a series of photos of the installation I did on one of my drill presses. The motor mounts where the hand crank used to be. The second photo shows what's "under the hood." The inside end of the output shaft is on the right (with a bunch of magnets and a reed switch to give position feedback to the controller). On the left, hidden behind the wiring, is a cam gear (slowed way down from the output shaft) that activates (settable) limit switches. Mine runs on 36VDC and raises the table at a reasonable speed - about 3 seconds per inch.

 

[Jim F]

If I remember correctly, his does not have a rack.

 

[hman]

True. I was thinking of coupling the dish positioner to the top of the threaded rod. Guess I failed to connect the dots

 

[Martin W]

3/4 hp should work fine.
Cheers
Martin

 

[7milesup]

Off topic....Hman, how did you bend that clear shield?

 

[projectnut]

You might want to consider a linear actuator. There are several available from the Surplus Center for prices as low as $25.00.

Surplus Center

They currently have 101 listings for various lift heights and weight capacities. They are listed in order of lift heights.