need specs for table-raising motor

[BTL-A4]

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. I've attached a sketch of 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. And they are really expensive. I'd like some help figuring out what I need so I can look for a less expensive alternative. Thanks!

 

[Dumber than lumber]

You should look for a local shop that services and rebuilds motors. They might have some used motors and could give you advice on what would work.

 

[Kaizen]

Does the table actually go both ways just pushing at that one point? All mine need to be lifted from front as they are designed to pinch stop


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[larry_g]

A big factor here is how fast do you intend to have the table move, the pitch of the screw and the frictions in the system. If you counter balance the table then all the numbers change. Google electric linear slide; https://www.google.com/search?sxsrf...&ved=0ahUKEwic3sG43YbuAhXAGDQIHXbyC70Q4dUDCA0

To start your research into the dynamics if such a system as you propose.

As drawn have you considered the trust load on the motor bearings?
Do you have to allow for the table to rotate around the column?


lg
no neat sig line

 

[mrolds88]

I would look at gearmotors.

 

[exmaxima1]

I would look at gearmotors.

+1
I used a reversible gearmotor that I bought at the local science shop on my drill press. An acme threaded shaft lifts/lowers the table in a nearly identical fashion to the OP's concept. Since I like to be able to rotate the table, my lift employs a collar that slides on the column rather than connecting directly to the table.

 

[Monza Harry]

+1
I used a reversible gearmotor that I bought at the local science shop on my drill press. An acme threaded shaft lifts/lowers the table in a nearly identical fashion to the OP's concept. Since I like to be able to rotate the table, my lift employs a collar that slides on the column rather than connecting directly to the table.

I would also consider using bronze or Oilite nuts with a space in between that can be adjusted for control of the backlash that will come, fit a grease Zerk there as well. I would use a flanged nut [fastened to the shaft] against a thrust bearing at the bottom. I think the drill idea is fine, cut the handle off and fashion a cover with a bottom cooling air intake away from the debris field. A 2L pop bottle with a little heat gun/hot water work, or a big metal coffee/tomato juice can would likely be better, even a 1 Gal. WD-40 can, maybe even leaving the handle. Harry

 

[chaosracing]

Window regulator motor. You just need a way to get 12 volt for it.

 

[Hal]

Electric jackscrew, don't know if they are made long enough, but it would do it all in one package.

 

[duc916]

Exmaxima1's solution along with allowing the table to swivel will also reduce the torque created when trying to lift the table at one point in the rear.

 

[BTL-A4]

+1
I used a reversible gearmotor that I bought at the local science shop on my drill press. An acme threaded shaft lifts/lowers the table in a nearly identical fashion to the OP's concept. Since I like to be able to rotate the table, my lift employs a collar that slides on the column rather than connecting directly to the table.

This is pretty cool. What type of "science shop" did you buy this at? Did it come with the threaded shaft?

 

[BTL-A4]

Does the table actually go both ways just pushing at that one point? All mine need to be lifted from front as they are designed to pinch stop


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I am concerned about the table binding, but it just slides up and down now, no pinch stopping. I'd need to take all the rust off the column and make sure it's as smooth as possible.

 

[BTL-A4]

A big factor here is how fast do you intend to have the table move, the pitch of the screw and the frictions in the system. If you counter balance the table then all the numbers change. Google electric linear slide; https://www.google.com/search?sxsrf...&ved=0ahUKEwic3sG43YbuAhXAGDQIHXbyC70Q4dUDCA0

To start your research into the dynamics if such a system as you propose.

As drawn have you considered the trust load on the motor bearings?
Do you have to allow for the table to rotate around the column?


lg
no neat sig line

It doesn't have to move fast. I just want an easier way to move the table up and down. I don't move it much.

I was thinking of having the threaded rod "float" in the coupling so there would be no axial forces transmitted to the motor.

I also thought the bottom motor mount could rotate around the column along with the table. In other words, the motor and table would be connected so they would rotate as one. Like I said, I don't move it much.

I'm thinking of going with a linear slide of some sort.

 

[larry_g]

If you blow up the above picture you can see that I used an air spring to counter balance my DP table. It's simple and works well.

lg
no neat sig line

 

[PugetDude]

Look at Burdens Surplus in Nebraska.
https://www.surpluscenter.com/

 

[Kaizen]

I am concerned about the table binding, but it just slides up and down now, no pinch stopping. I'd need to take all the rust off the column and make sure it's as smooth as possible.

Perhaps design the mechanism so you can make a support out to the table front just in case


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