Are all 2 hp motors created equal?

[Daryl Parks]

I have an opportunity to get a Powermatic 3520b at a deeply discounted price. I currently own a Jet 1642 with a 2 hp motor. I called Powermatic tech support and they could not answer my question. Is the 2 hp motor on the Jet the same as the 2 hp on the Powermatic? I turn and sell around 100 bowls a year. Bowls in the 12 inch to 14 inch range sell the quickest so my interest is not in turning larger bowls. I would just like more torque. Any help will be greatly appreciated.

[Reed Gray]

There should be specs on the motors for amps, and volts. If they are from the same manufacturer (Leeson and Baldor are probably the best), then they should be very similar. I have a couple of grinders. One is an old blue no name grinder that Woodcraft carried for a long time. The others are Baldor. Both are rated 3/4 hp. The Baldor is rated 4 amps, the no name is rated 6 amps. The Baldor weighs 90 plus pounds, the no name about half that. I can easily stall the no name one, and might be able to stall the Baldor if I really tried. So, no, all equally rated motors are not the same.

robo hippy

[Dick Mahany]

The VFDs for the motors are the same OEM model number between the Jet 1642-2 and the PM 3520B, so I would think the motors would be equal (if not identical). I have the 1642-2.

[Scott Conners]

No, motors are not equal. Bearings, winding density and neatness, copper quality, magnet strength, design, etc all make a difference. Theoretically they measure the output ofter the motor is built and the tag on it is truthful, but not all manufacutrers However, between those two lathes, the motors are probably pretty much equal. I assume you already have the belt on the large pulley on the spindle (top)?

If stock appearance isn't important to you, it might be possible to upgrade the motor and VFD on your current lathe.

[Michael Poorman]

Daryl,

I'm assuming that the two motors are both rated at the same speed. HP is a function of torque, RPM, and voltage. So, a lower speed motor with the same voltage and HP rating will have higher torque. I switched the motor on my shop built bowl lathe from an 1800 rpm to 870 rpm motor and the torque gained is amazing! If the voltage, rpm, and hp rating all equal both motors should deliver the same amount of torque.

Hope this helps.

[Michael Mills]

Between the two you mentioned I think that they should be very close. No, all stated 2 HP motor are not created equal.
When I did some searching a few years back I found the same” number” from a every resource. That number is 1 HP = 746 watts (amps X Voltage). The wild card is efficiency. I always check the amps and ignore (to a large degree) what the marketing department says about HP.

This short article explains it in layman’s terms. This article is for AC and they are generally less efficient than DC motors. The best data I can find is that most DC motors are 80-90% effective so they require less amps than AC motors with 60-70% efficiency.

http://www.kevinsbrady.net/motors.pdf

If you really want to upgrade you may want to buy one of these, install the motor on your lathe, and trash leftover parts. You now have a 6 ½ HP lathe for about $150. Right!

http://www.sears.com/shop-vac-6.5-peak-hp-shop-pac-174-back/p-00913412000P?prdNo=1&blockNo=1&blockType=G1

[David C. Roseman]

[snip]I called Powermatic tech support and they could not answer my question. Is the 2 hp motor on the Jet the same as the 2 hp on the Powermatic? [snip]

I'm a little surprised that the tech couldn't have determined that with a few mouse clicks in the Jet data base, or at least a phone call. But maybe not. Out of curiosity, I checked the online parts lists for the two lathes. The replacement motor for the 2hp Jet is $500, and for the PM it's $533. Jet's pricing algorithms for the two lines could of course be very different for marketing reasons. But given that they're both billed as 2hp motors by the same vendor, I'd suspect the motors are pretty close in performance as well. I also second Dick's observation that they use the same inverter. It's the Delta Electronics VFD-S 1. However that drive is rated for a range of hp at 220v on Delta's website, so I don't think that's necessarily dispositive.

If you do get a firm answer, please update us.

David

[Reed Gray]

Another consideration is how the inverters are programmed. You can change torque and rpm, both up and down. I had that done with my Robust, and Brent's help.

robo hippy

[Mike Goetzke]

I'm a new turner, but, if power is equal might there may be other reasons to get the 3520B over your Jet since you can get it for a good price?

Mike

[Daryl Parks]

Thank you for your input. My decision is made. One Way 2036 with 3 hp motor.

[Olaf Vogel]

No they are not all equal. A good motor should have a "service factor" (a measure of periodically overload capacity at which a motor can operate without overload or damage).
A higher SF is typically an indication of a more powerful motor - also heat fins etc.

Additionally is seems like horses got smaller over the years. I have several old induction motors from the 1930's. My old 2 hp motor is backbreaking and twice the size of my new 5 hp motor which I can easily pick up.
While I've not tested the amp draw them, I've had them both mounted on my bandsaw. The old 2 hp has more torque.

And if I compare that 2 hp motor against the 3.5 hp DC treadmill motor....well, the DC motor is TINY...and gutless, it went onto C-list quickly.

I think both the Jet and PM have fairly integrated motors so your options are limited, but if you can mount one externally and use 3 ph, then the options are limitless.

Gearing will help the most though. My 3 hp on the lathe (with VFD speed reduction) would stall out easily on large bowls until I reduced speed with extra gearing.

Olaf

[David C. Roseman]

Thank you for your input. My decision is made. One Way 2036 with 3 hp motor.

Well, that'll work too. Enjoy your new lathe!

David