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



## ARC-170 (Jan 5, 2021)

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!*


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## benmychree (Jan 5, 2021)

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


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## itsme_Bernie (Jan 5, 2021)

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


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## Jim F (Jan 5, 2021)

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.


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## hman (Jan 6, 2021)

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.


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## Jim F (Jan 6, 2021)

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


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## hman (Jan 6, 2021)

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


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## Martin W (Jan 6, 2021)

3/4 hp should work fine.
Cheers
Martin


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## 7milesup (Jan 6, 2021)

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


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## projectnut (Jan 6, 2021)

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.


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## CluelessNewB (Jan 6, 2021)

Old school commercial copy machines typically had 110V AC gear motors that would be perfect.  10 years ago free scrap machines were plentiful.  I'm not sure how many of them are still around.


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## rwm (Jan 6, 2021)

Would it be easier and maybe cheaper to just buy the linear actuator as a unit?









						1000N Heavy Duty Linear Actuator Stroke 12V 2"-18"Electric Motor for Door Lift  | eBay
					

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OOps someone already said that! Also, I might consider mounting in front of the pole to get closer to the CG of the table.
Robert


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## talvare (Jan 6, 2021)

ARC-170 said:


> *Specifically, what torque spec am I looking for?* I'm not sure how to go about calculating it.


A few years ago I built a drive for the knee of my BP mill and I had the same question. So, I kind of used the caveman method to determine what I needed. I put 200 lbs of weight on the mill table and used my torque wrench to crank the table up. I just kept adjusting the wrench until I could establish the minimum amount of torque required to raise the table. I think I added about 25% to that value for selecting a gear motor.  I also determined the speed in kind of the same manner by just cranking the table up, counting and timing the number of turns to establish a speed that was acceptable to me. It all worked out very well. Just some food for thought.
Ted


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## sdelivery (Jan 6, 2021)

I think I would use the motor and gear reduction from a chip conveyor.


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## ARC-170 (Jan 6, 2021)

benmychree said:


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


I know, but in the 20 or so years I've had this, I've moved the table out of the way exactly once. I think it will be able to be lowered enough to handle just about anything long that I need. If not, I can remove the riser mechanism.



itsme_Bernie said:


> 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


There might be, but it's really pricey.
I thought of using an angle drive, but I'm sure there are motors out there that do what I want. I want to keep it simple and uncluttered.



Jim F said:


> 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.


Yes, I'd probably mount the motor to a plate on the column. I didn't show it because I haven't designed it yet. I wanted to see what type of motor I'd need first.
I also thought of a counter-weight in the column, but I don't have a really good way to attach a pulley. There's not enough metal to securely attach one. I may revisit this, though.


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## ARC-170 (Jan 6, 2021)

hman said:


> 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.
> ...



It doesn't need to go fast, so a slower motor is fine.
Good point on mounting the threaded rod. Maybe I'll offset it and have a gear drive. I wanted to keep it simple, though. I thought mounting the motor on the column or the base would spread/transfer the load to that. I also thought the coupling would "float" on the shaft and not transfer any axial force to the motor. 
I'm not going to raise and lower this all the time; just infrequently. It's heavy and I'm tired of doing in manually.

There's an electric motor place nearby, so I may go there and see what he has.


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## Papa Charlie (Jan 6, 2021)

These have a 1320lb capacity and are a complete unit. For $79 you can raise and lower the table up to 18".









						DC 12V Linear Actuator 1320lbs W/ Remote Controller Electric Motor 6000N Lift IG  | eBay
					

This is 6000N DC 12V linear actuator made by high quality aluminum alloy material, it has built-in limit switch. The actuator can provide a pushing force of up to 6000N and a pulling force of up to 4000N.



					www.ebay.com


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## ARC-170 (Jan 6, 2021)

projectnut said:


> 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.



Thanks! I thought of something like this, but didn't know they could be bought as a unit; I thought they had to be custom-made.

I'm gonna need to figure out how much weight I need to lift.

Another option is to use a bolt-on trailer jack from Harbor Freight. This is klugy and not very elegant, however, it's cheap and it works! When I was researching this, many of the people with Craftsman 2.75" diameter columns like me were told to do this, since there doesn't seem to be any other solution out there.


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## ARC-170 (Jan 6, 2021)

talvare said:


> A few years ago I built a drive for the knee of my BP mill and I had the same question. So, I kind of used the caveman method to determine what I needed. I put 200 lbs of weight on the mill table and used my torque wrench to crank the table up. I just kept adjusting the wrench until I could establish the minimum amount of torque required to raise the table. I think I added about 25% to that value for selecting a gear motor.  I also determined the speed in kind of the same manner by just cranking the table up, counting and timing the number of turns to establish a speed that was acceptable to me. It all worked out very well. Just some food for thought.
> Ted



Good idea! But, I don't have any way of using a torque wrench on this. The table is raised by loosening a lock and lifting or lowering by hand, as there is no crank. I need some way to measure how much force it takes to pull it up and push it down. I thought of using a scale; maybe I'll try that.


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## hman (Jan 6, 2021)

7milesup said:


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


The material is ~1/16" polycarbonate (Lexan, Hyzod, etc.) that I bent with my vise brake.  It would probably have taken full 90º bends with no problems, but I chickened out and did double 45's.








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## AGCB97 (Jan 6, 2021)

See my drill motor powered lifter here at POST #5
(61) Drill press table lifter | The Hobby-Machinist (hobby-machinist.com)


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## Papa Charlie (Jan 7, 2021)

hman said:


> The material is ~1/16" polycarbonate (Lexan, Hyzod, etc.) that I bent with my vise brake.  It would probably have taken full 90º bends with no problems, but I chickened out and did double 45's.
> 
> 
> 
> ...



Nice work, professional looking end product.
Did you heat the material or just use the pressure of the vise brake?
Also, I assume the Polycarbonate had a protective coating on it? Can't see a single mark in the picture.


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## Lo-Fi (Jan 7, 2021)

To allow the table to be swung, you could attach the threaded rod to a collar around the pillar underneath the table. This also prevents an accidental swing of the table from twisting up any mechanism attached directly to it (table unlocked, walking past and catching on something, pulling the table etc.). I've also found that swinging the table is useful when clamping stuff to the table to be able to get the slots in convenient places.

I'd go with a linear actuator. Almost any will be powerful enough, they're cheap and readily available. If you need full travel, look at running a wire or chain from the base, over a pulley on top of the actuator, then down to the table. Doubles the throw, though halves the power. It's how most forklifts work.


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## ARC-170 (Jan 7, 2021)

I think I will look at the linear actuator. The 1000N one on Ebay looks like it will handle over 200 lbs, so that might work. My issue is whether or not the collar will slide on the column easily, especially if the actuator is not pushing directly on the collar. I may have to remove the column and get rid of the rust and get it smooth.


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## ARC-170 (Jan 7, 2021)

Lo-Fi said:


> To allow the table to be swung, you could attach the threaded rod to a collar around the pillar underneath the table. This also prevents an accidental swing of the table from twisting up any mechanism attached directly to it (table unlocked, walking past and catching on something, pulling the table etc.). I've also found that swinging the table is useful when clamping stuff to the table to be able to get the slots in convenient places.
> 
> I'd go with a linear actuator. Almost any will be powerful enough, they're cheap and readily available. If you need full travel, look at running a wire or chain from the base, over a pulley on top of the actuator, then down to the table. Doubles the throw, though halves the power. It's how most forklifts work.



Yeah, I probably need to figure out how to attach this so it can swing with the table. I don't actually swing it much at all; I have a mill drill if I need to clamp something, but I do occasionally need to rotate the table.

I may not need more than 18" or so of travel, but thanks for the tip!


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## Lo-Fi (Jan 7, 2021)

You could just plumb for balls joints attaching the actuator to the base and table. It'll raise and lower a tad when you're swinging the table, but doesn't sound like that'll worry you. Should get a good range of swing, no worries about binding and a nice simple install.


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## hman (Jan 7, 2021)

Papa Charlie said:


> Nice work, professional looking end product.
> Did you heat the material or just use the pressure of the vise brake?
> Also, I assume the Polycarbonate had a protective coating on it? Can't see a single mark in the picture.


Thanks!  
Polycarbonate is easy to bend at room temperature - very tough.  Just be sure to leave good clearance between the hold-down fingers and the folding bar if you're using a "traditional" box brake.  And yes, I marked on the paper liner ... probably with a pencil.  When using the vide brake, I line the mark up to the "male" finger, start to squeeze lightly, then do a squareness check with a small drafting triangle.


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## mattthemuppet2 (Jan 7, 2021)

if you can, stick the raising mechanism under the table (in front of the column), not at the back. The weight on the table tilts the table on the column ever so slightly down at the front - if you put the raising mechanism at the back you'll be pushing even harder in the same direction. Pushing from underneath in front of the column will straighten the table on the column and it'll move much more easily.


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