South Bend lathe phase change?

I just bought an old South bend 16" lathe and am trying to decide on whether to change the original 3 phase 2 HP motor to a single phase 2 or 3 HP
motor.
Can it be done without changing the power switch? Is it a good idea or should I just get the phase converter. If I do go with a phase converter it will be the one I saw in the Grizzly catalog. I think it's called a static converter.
Any Thoughts or ideas on this to help steer me in the right direction will be much appreciated.
Thanks,
Ted
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Ted wrote:

I would change it out to a single phase motor. You can do this without replacing the power switch. You will have to re-wire it, but the switch should be usable.
Good Luck, Bob
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Ted wrote:

I think your best option would be to keep the 3ph motor and get a VFD inverter drive instead of a static phase converter. VFDs are fairly cheap these days and will give you variable speed, soft start / stop and other features that will be a benefit. I think the TECO drives are pretty inexpensive. Dealers Electric seems to be pretty well regarded around here and carries the TECO drives.
Pete C.
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Ted wrote:

I would agree with Pete C. and get a VFD from Dealers Electric (or any place else you trust). I just converted my single phase SB11" to three phase with a VFD and I am a happy camper. If you search Google you'll find my post about how well Dealers Electric treated me - good folks.
Peter
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The VFD is the best option for sure, next on the list would be a phase converter that would be very inexpensive. To have the foward/reverse you will need to rewire the switch, I have done it but it would be less time to hook up a vfd or converter. One thing nice about the vfd is you can change the speed on the fly, its a nice way to dial in the best cut speed.

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There's always a contrary opinion. My 13" South Bend was 3 ph when I bought it and I replaced the motor with a 2 HP 240V single phase and used the original relays for control. The only difference from the original 3 PH is the lack of instant reverse. I've only been using it for 15 years or so, so there may be drawbacks I haven't found yet.
George Willer

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Thats good, I have had to rewire the tumbler on the ones I have changed.

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George Willer wrote:

I think the point is that the economics have changed to the point where a new inexpensive VFD is in the same range as a new motor or a commercial phase converter. If you have to spend real money to buy a new single phase motor or buy a phase converter, you are better off spending nearly the same amount of money on an inexpensive VFD and getting some extra capabilities. If you can find a cheap used single phase motor or build a phase converter from scrap parts then the economics are different.
Pete C.
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Thank you all for your input. I think I'm going to attempt the VFD route. I was somewhat concerned about the motor I have. It is a vintage 1975 3 phase 3 HP GE motor (I stand corrected by Leblonde. I thought it was 2 HP based on the original owners info.) It being that old I thought it might be on its way out. I just looked up prices in an old Grainger's catalog and to my surprise 3 Phase motors are less expensive and supposedly last longer than single phase!
So I'm willing to try a VFD. Besides, unknowingly, I've been running my General woodturning lathe on a 3 phase motor with a Square D Altivar (VFD) for the last 6 years and love the variable speed control.
Thanks again. I'll keep you updated.
Ted
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Ted wrote:

"That old"?
I think you'll find, Ted, that lots of people here are using motors even older than that. Why, some of them even date back to the sixties!
And to the fifties, and to the forties.....
I'm guessing that the motor on my shaper dates to the twenties.
Electric motors are good for a long time. Replace the bearings when needed, clean the switch contacts, replace brushes if present and a motor may outlast you. Heat is the enemy, so keep the dust out so it can cool.
Many of the older motors were built better than modern ones. Almost all newer motors are "inverter rated" though, which means they can be used with a VFD. The older motors weren't, which means that the spikes and fuzziness in three phase current generated by a VFD can harm them. That said, I have yet to see one that has been harmed.
John Martin
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[snip]
If one uses the line inductors that go between VFD and motor, the inverter hash will largely be kept out of the old motor, which will then see very clean 3-phase power. That said, if the motor runs cool without the inductors, probably there is no problem.
Joe Gwinn
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On Wed, 15 Mar 2006 10:56:03 -0500, "Ted"

Call or write GE with the lathe motor model number and get the specs first. A motor not originally designed for use with a VFD will have some restrictions placed on it as to how fast or slow you can run it, and the duty cycles and effective HP output will change.
They might call for an external motor cooling fan at slower speeds, in addition to a relaxed speed or duty-cycle restriction.
--<< Bruce >>--
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Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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