Switch from 3 phase to Single Phase Saw Motor

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Forum topic by TurbineTester posted 11-08-2011 06:37 PM 17799 views 0 times favorited 21 replies Add to Favorites Watch
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197 posts in 2910 days

11-08-2011 06:37 PM

I got a steal of a deal on a refurbed 5HP 3ph PM66 a while back. I don’t have 3ph power and I haven’t been able to get my hands on a good deal on a VFD or rotary phase converter so i was thinking of just getting a Single Phase 5HP motor and using it instead of the three phase motor. I’ll just hang on to the 3 phase motor for now. Where would you go to get a 5HP single phase motor for this saw? Would you buy a used one or a new one? Best source for new and used? thanks!

-- if you can't light a $100 bill on fire and watch it burn, you're in the wrong hobby.

21 replies so far

View crank49's profile


4030 posts in 2967 days

#1 posted 11-08-2011 07:19 PM

This is a link to Grizzly. Advertized price of $369.

I don’t know your location so of course freight might eat you up, but it’s a number to start with.

Around here, Tennessee, I’d go to a Tractor Supply or Co-Op as most farm supply stores have motors in stock.

Graingers or Northern Tool are more sources.

Of course for used it would be prudent to check Craigs List.

View Bill White's profile

Bill White

4929 posts in 3957 days

#2 posted 11-08-2011 07:23 PM

Not an electrician here. I didn’t know that you could power a 5 hp motor (real 5hp) on single phase. Why not check with an electric motor shop. Might even be able to work out a swap of some sort.


View John Ormsby's profile

John Ormsby

1285 posts in 3733 days

#3 posted 11-08-2011 07:30 PM

I had a 5 hp single phase powermatic saw and I assure you it will be no problem running on a 220 volt single phase circuit providing you have the necessary amount of available power in your shop.

You will also need to replace the switch. These motors are not chap and will most likely cost around $500 when done. Not including running the 220 receptacle.

A good high quality phase converter seems runs about $2,000 to $2,500.

-- Oldworld, Fair Oaks, Ca

View crank49's profile


4030 posts in 2967 days

#4 posted 11-08-2011 07:35 PM

Baldor makes single phase motors from 1/12 up to 15 hp. Not sure about other manufacturers.

I might point out that a rotary phase converter has to have a single phase motor in it to run the 3 phase generator. And, since nothing is 100% efficient it would have to have a bigger single phase motor than the size of 3 phase motor it is capable of running.

A static converter uses capacitors to trick a 3 phase motor into running on single phase, but it will only have about 66% of its rated power.

A VFD is the best solution as it actually creates 3 phase power from rectified single phase.

View TurbineTester's profile


197 posts in 2910 days

#5 posted 11-08-2011 10:01 PM

I would love to have VFD. My Brother in Law works for an automation company, but because of the recent flooding and other issues in Japan, many of the manufacturers had supply issues the latter part of spring and into summer. Normally my BIL would have been able to get me a good deal on a VFD, but because of that there were none to be had for employee purchase. On top of that in order to run a 3 phase motor with a VFD you have to make sure that the motor wiring is rated for inverter duty. According to BALDOR the SAW DUTY rating is not synonymous with INVERTER DUTY and they do not recommend using this motor with a VFD. Most likely i would not have a problem, but for information’s sake: there is it.

I have a 5HP single phase motor running my clear vue cyclone separator on 220V and i already have a 220v receptacle in my garage 2 feet from the service panel that i wired in preparation for this at the same time i ran the service wiring for the dust collector.

I actually have a 3HP rotary phase converter, but as you mentioned, it’s not suitable for this saw. Electric motors draw maximum current on startup, and if you have an undersized phase converter you will get loud erratic rotation out fo the motor as it tries to vibrate it’s way up to 3450 RPM. Correct me if i’m wrong, but the way a rotary phase converter works is by powering two legs of an oversized 3 phase motor with 2 220v single phase lines and capacitors, and then drawing the third leg of power back off the same motor using that third leg as a generator. So with the combinationof the 220v two line single phase current in your house typically used for your dryer/stove, plus the thrid leg off the rotary phase converter, you get three phases. But becuase of that setup you need to OVERSIZE the rotary phase converter by 50% of the motor you want to DRIVE. Or more simply, in order to run a 5HP 3ph motor you need a 7.5HP rotary phase converter.

I checked craigslist for electric motors in my area and there is nothing to be had right now. I have a 5HP BALDOR motor and a 3HP Rotary Phase converter i might be willing to trade for a 5HP single phase motor…anyone interested? :) Any other suggestions?

-- if you can't light a $100 bill on fire and watch it burn, you're in the wrong hobby.

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197 posts in 2910 days

#6 posted 11-08-2011 10:08 PM

Rick – Now that’s something i guess i should take into account, just getting a 3HP. I think you are right in that i would be hard pressed to exceed the capacity of that with my infrequent use of my TS.

-- if you can't light a $100 bill on fire and watch it burn, you're in the wrong hobby.

View crank49's profile


4030 posts in 2967 days

#7 posted 11-08-2011 10:41 PM

Rick, I stand corrected. I was thinking about a converter I installed on an induction melting furnace a few years ago. But that was the exact opposite. I had to have 500 KW of single phase for the furnace coil and used a MG set with a 3 phase motor running a single phase generator. But, the efficiency thing is still an issue. You can’t get 100% of the energy out of any system that you put into it. There is always a loss.

View cabmaker's profile


1730 posts in 2805 days

#8 posted 11-09-2011 12:49 AM

That saw is worthy of a real motor. Get a 5hp baldor and be done with it.(single phase of coarse)

View Bill1225's profile


125 posts in 2396 days

#9 posted 11-09-2011 12:57 AM

i think the powermatic 66 has an odd mount so be careful when buying a motor i do know though baldor does make it

View TurbineTester's profile


197 posts in 2910 days

#10 posted 11-09-2011 03:51 PM

It’s hard to justify spending $800+ when a perfectly suitable 5HP 1ph motor can be had brand new from BALDOR for about $400. Do you know of a good place to get a reliable inexpensive VFD?

Ooops well never mind it looks like that are closer to $500 from baldor…

-- if you can't light a $100 bill on fire and watch it burn, you're in the wrong hobby.

View TurbineTester's profile


197 posts in 2910 days

#11 posted 11-23-2011 04:44 PM

Ok so here are some developments in this search. The original BALDOR motor is a 184C frame made specifically by a sub contractor of BALDOR for Powermatic for the PM66 line of TS. The current replacement part from PM are as follows
5HP 1Ph is 6472335 – ~$750
3HP 1Ph is 6472028 – ~$650

First things first, that price is absolutely ridiculous and they must be making about an 80% profit margin on those motors.

According to PM the replacement motor is a 145TC frame. They say it’s a special motor, but they can’t give me the dimensions on the motor face bolt pattern to show that it is actually diffferent from the standard 145TC mounting dimensions.

Here is a NEMA frame chart for anyone who is interested…

Just so everyone knows, you can get a 5HP 1Ph, 230V, 145TC, Leeson motor NIB from Electric Motor Warehouse for $350 plus shipping.

Has anyone swapped a 5HP 3Ph for a 5HP 1Ph motor in one of these saws?
What did you have to deal with regarding the dimensions for the face frame mounting holes on the motor vs. the saw?
Are they the same?

-- if you can't light a $100 bill on fire and watch it burn, you're in the wrong hobby.

View chuckman's profile


2 posts in 1557 days

#12 posted 02-16-2014 05:55 PM

Turbine Tester:
I have the same predicament only with a PM2000. What did you end up doing (phase convertor or new motor) ?

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1945 days

#13 posted 02-16-2014 06:28 PM

IMHO I would just go with a static converter. You only be running at 2/3 power, but 5hp at 2/3 power is still plenty. I went the route of a rotary, because it is an investment that will allow for more equipment in the future.
Here it what I did. I highly recomend phase-craft. The owner/operator is very honest and knowledgeable.

View Loren's profile


10382 posts in 3644 days

#14 posted 02-16-2014 07:20 PM

+1 on Phase-craft. There are two minor annoyances with
rotary conversion:

1. The idler makes a sound. It’s not very loud but it bothers
me anyway. I put my idler outside so even if it’s just a minor
hum inside the shop. Of course I had to plan to put it
outside so I used a longer conduit than I otherwise would
have used to connect the idler to the panel.

2. You may have to run some heavier gauge wiring to the
phase converter panel and you’ll need a dedicated breaker.

You can run a 3hp table saw motor easily with a 5hp rotary
converter. That size converter requires a 30amp 220v circuit.

View longgone's profile


5688 posts in 3305 days

#15 posted 02-16-2014 07:38 PM

Try some blogs, Craigslist or other woodworking websites to see if anyone with a 1 phase motor wants to trade for a 5hp three phase…there just might be someone out there wanting to upgrade in motor size.

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