I scored a Powermatic 1150a Drill press (and now I have questions)

[Aaron Hoover]

So, I managed to score a working variable speed Powermatic 1150a drill press (dark green and SN starts with 78, so let's assume it's about 40 years old) for $250 from a woman who inherited it from her father.

When I went to check it out, I saw that it was wired for 120V and I tested that it worked - . Her basement was dark, so I didn't closely examine the motor plate.

When I got it home, I found that the Leeson motor plate lists the motor as 3 Phase, 230V (and 3HP! - my understanding was the these came standard with 3/4 HP motor). But, it works fine on single phase 120V. There's no VFD or phase converter attached as far as I can tell. One thing I did notice is that there's a cylindrical cover screwed the back of the motor housing that appears to guard a big capacitor.

So, my question for you all, is how is this thing running on 120V? Should I be concerned? I don't yet have 220V service in my shop, and I was only planning on adding it for my table saw and jointer.

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[Matt Day]

I don’t know how it’s working but it can’t be good. My guess is that you’re getting a fraction of the 3hp and it’s likley bad for the motor. I wonder if the PO thought the stock 3/4hp 3ph motor wasn’t powerful enough and upgraded the motor, but it was because he didn’t know it was 3 phase.

I’d get a VFD for it, or since it’s way overpowered maybe a static phase converter since they’re cheaper. The SPC cuts the hp by 1/3, but You don’t need full hp anyway.

Great DP and great price by the way! Congrats.

[Martin Siebert]

A three phase motor cant run on 120 volt single phase power. Before you buy anything I would suggest you consult with a local electrician and see exactly what you have there. Not knocking your machine, but 3 horse power 3 phase for that drill press seems "excessive"....I doubt that's what it is. Switching over to 3 phase 3 HP on a shaper maybe, a big planer or big wide jointer maybe, but a drill press that size??? On the other hand, that wouldn't be the strangest thing I've ever seen if it was...could the person you got it from have had 3 phase power run to it when you tried it or was it a standard 110/120 volt plug in a receptacle when you picked it up???

[Aaron Hoover]

Yeah, I was a little shocked to see the 3 HP stamp on the motor as well. Weird thing is it looks like motor is original (well, at least the paint matches).

I'm pretty certain she didn't have 3 phase power - it was plugged into a standard power strip (and it has a standard 120V three prong plug on it).

[Joe Jensen]

I have a PM1150 drill press with a 3/4HP three phase motor. Mine is 1725 RPM with what looks to be the same drive. Your motor is 3450 RPM which doubles the speed. If mine I would ditch the 3HP motor and buy the right frame 3/4HP Single Phase motor.

Here is a pic of my motor plate.

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[Bill Space]

The box you mention holding a capacitor may actually hold a static phase convertor setup. They are made up of a couple capacitors and perhaps a resistor. I have one that powers a three phase motor on a lathe.

You cannot develop motor nameplate HP when using a static phase convertor setup. But on that drill press you only need a fraction of the 3 HP anyway. The speed of the motor may be a greater concern, if the drill press is designed to run on a nominal 1800 rpm motor.

You can google static phase convertor and learn more of the details about them.

Looks like the pulley ratio in the picture is set to run the spindle as slow as possible.

Chances are pretty good that the previous owner used that drill press as it sits. If that is a variable speed setup, you want to be careful cranking up the speed, as it apparently will run at double the design speed for any speed setting.

Bill

[Aaron Hoover]

The box you mention holding a capacitor may actually hold a static phase convertor setup. They are made up of a couple capacitors and perhaps a resistor. I have one that powers a three phase motor on a lathe.

You cannot develop motor nameplate HP when using a static phase convertor setup. But on that drill press you only need a fraction of the 3 HP anyway. The speed of the motor may be a greater concern, if the drill press is designed to run on a nominal 1800 rpm motor.

You can google static phase convertor and learn more of the details about them.

Looks like the pulley ratio in the picture is set to run the spindle as slow as possible.

Chances are pretty good that the previous owner used that drill press as it sits. If that is a variable speed setup, you want to be careful cranking up the speed, as it apparently will run at double the design speed for any speed setting.

Bill

Ahh, yes, this makes sense! When I cranked up the speed control on the front when I was testing it, it seemed *wildly* fast. I have a tachometer at work I can use to accurately measure the speed. I think swapping the motor out makes the most sense at this point.

[Geoff Crimmins]

The cylindrical hump on the side of the motor would seem to indicate the presence of a start capacitor, which is only used on single-phase motors. As has been mentioned, the RPM and HP of that motor aren't a good fit for that bandsaw, and yet the paint matches. The hammered green Rustoleum spraypaint is a pretty good match for that Powermatic green, though, so who knows. I like the idea of taking the the drillpress, or at least the motor, the an electrician that repairs motors and find out what exactly you have there. Great drillpress, BTW. I don't know that you can buy a new drillpress of that quality, and if you can you wouldn't like the price. I you end up having to replace the motor, be very careful removing the Reeves drive pulley from the old motor. A replacement would be hard to find, and would likely cost as much as paid for the drillpress. Also, I think the motor has to have a specific frame in order for the pulley and belt to fit correctly.

[Aaron Hoover]

The cylindrical hump on the side of the motor would seem to indicate the presence of a start capacitor, which is only used on single-phase motors. As has been mentioned, the RPM and HP of that motor aren't a good fit for that bandsaw, and yet the paint matches. The hammered green Rustoleum spraypaint is a pretty good match for that Powermatic green, though, so who knows. I like the idea of taking the the drillpress, or at least the motor, the an electrician that repairs motors and find out what exactly you have there. Great drillpress, BTW. I don't know that you can buy a new drillpress of that quality, and if you can you wouldn't like the price. I you end up having to replace the motor, be very careful removing the Reeves drive pulley from the old motor. A replacement would be hard to find, and would likely cost as much as paid for the drillpress. Also, I think the motor has to have a specific frame in order for the pulley and belt to fit correctly.

Thank you for the advice about the Reeves drive pulley - I'll be extra careful trying to get that off.

I managed to find an electrician that specializes in motor service pretty close to my house. So, I think I'll try to get the motor off the press and take it in (there's no way in hell I'm taking the whole press in - this thing weighs 300+ lbs) to shed some light on this mystery.

[Bill Dufour]

I looked it up Leeson was founded in 1972 by Lee Doer's sons after dad sold Doer motor company. So it could be original.
If it is three phase you could run as is or add a vfd to the existing motor bypassing the phase converter. Three phase and a vfd is much nicer on a drill press then single phase. The PM drill press in the auto shop has a big box on the side like that. I know it is single phase 120 volt plug.
That dp is currently sold with 1.5hp three phase motor. My Walker Turner 20" dp has a one hp motor on it that I added with a vfd for fast reverse and variable speed. I bought it with no motor but it had the original motor pulley. I think one hp is plenty for wood working. I forget if it is mt2 or mt3 in the spindle.
Bill D.

[Rollie Meyers]

The motor is a single phase model, I would say the motor being marked as 3 phase was a typo, wish the first photo showed the entire motor data plate.

[Richard Coers]

The motor is a single phase model, I would say the motor being marked as 3 phase was a typo, wish the first photo showed the entire motor data plate.

The motor plate also does show L1, L2, and L3 in the schematic. That would be correct for a 3 phase motor. So the 3 stamped in the box is not a typo. More likely the motor plate was incorrectly screwed to the wrong motor. BUT, the motor guy will resolve all speculation.

[Dan Hall]

Just to add to the confusion I'm thinking that that motor does not look like a 3hp motor. It's not big enough. I'm going with the wrong data plate opinions. I don't think a motor with 230 volt windings is going to run on 120 with a static convertor or not.

When it starts can you hear the centrifugal switch drop out? Big click when it happens. They don't build polyphase motors with centrifugal switches. In a single phase motor you have a separate set of windings to get the motor up to speed then the centrifugal switch drops the capacitor out.....if I remember my motor theory right.

Nice press either way!

[Aaron Hoover]

The motor is a single phase model, I would say the motor being marked as 3 phase was a typo, wish the first photo showed the entire motor data plate.

I pulled the motor off today to take it to an electrician. Here's a better shot of the motor plate:406906


I think the motor is almost certainly not original. For one thing, you can see the green spray paint overspray on the motor plate. Also beneath one of the wiring junction boxes, the color is more of a metallic blue.

[Bob Vaughan]

I'm going with the wrong data plate opinions.!

I'll second that.
A C145TC frame is a face mount motor typically found on the Powermatic 66 table saw. The 66's motor was also a 3450 rpm motor.
A 1750 rpm motor on an 1150A will run a bit at about 450 rpm at the slowest speed.

[Bob Vaughan]

The overspray actually defines it as original Powermatic.
Powermatic painted the blue Leeson motors to match the machine they were building at the time. This practice continued through several decades. Below is a 1980s motor on the right that clearly shows the Leeson blue where the gold paint didn't get to.

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Google motor frame size dimensions. A 145TC frame has a 7/8" shaft. A 56 frame motor has a 5/8" shaft. Reading some overall dimensions and comparing them to your existing motor should tell you a lot.

[Jeff Burt]

I'm excited for you. I picked up an 1150a with step pulleys a few months ago and it's been fantastic. I'm really curious as to what the electrician says. Mine had a 3/4 hp baldor motor

[Aaron Hoover]

Okay, so I did a bit more sleuthing over at OWWM.org, and the consensus (based on the wiring) seems to be that it's a single phase, dual voltage 115V/230V motor that was just badged incorrectly. I'm going to measure the spindle RPM with a tachometer in the next couple days to verify that it's a 1725 RPM motor, but things are looking up!

Thanks for the all the help and suggestions.