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How to replace unisaw motor

peds

Plastic
Joined
Jan 10, 2020
Hey there i just bought a rockwell unisaw and it came with a 3 phase motor. I want to replace the motor with a 110 single phase 1.5hp and am having trouble finding one or use a vfd. I want to change the motor because i dont have three phase connection. Any ideas on options and can i use the three phase switch box that came with the saw with single phase? Thanks

Motor specs:
3 phase
2hp
575 volts
3450 rpm
145 frame
60 cyc
2.1 amp

motor 060.jpgmotor 058.jpg
 

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You can find single phase 1.5hp motors in 110/220v, but you need heavier wire, short run, dedicated circuit, and you might squeak by without tripping breaker as startup amperage is too high, you would be better served running 220v 1ph.
 
You may be better off buying a VFD and using the existing motor. The Unisaw motors have a special mounting and don't have a standard motor base. Most likely there isnt much to choose from with their mount system.
 
Hey there i just bought a rockwell unisaw and it came with a 3 phase motor. I want to replace the motor with a 110 single phase 1.5hp and am having trouble finding one or use a vfd. I want to change the motor because i dont have three phase connection. Any ideas on options and can i use the three phase switch box that came with the saw with single phase? Thanks

Motor specs:
3 phase
2hp
575 volts
3450 rpm
145 frame
60 cyc
2.1 amp

View attachment 275000View attachment 275001

I have a new single phase direct replacement motor available, I can get the info over the weekend.

Kevin
 
I made a mount for a 3hp motor for my old Unisaw. I used some big angle like 3x4 inch. I think I lost like 1/8" on cutting depth if any. You will have to replace the heaters in the overloads to run a 240 volt motor. You only need two heaters not all three. Or you can jump the heaters with solid wire and lose the overload safety effect.
Before you get too involved check the coil to see if it is 240 volts or less. If it is 440 it is probably cheaper to ditch the switch gear and install a newer adjustable contactor inside the existing box.
Other wise you will need two new heaters and one new coil.
Bill D
 
I run my 3 phase uni-saw via a static phase converter and it works perfectly. It uses the stock electrical components and was very simple and inexpensive to do.

Stuart
 
I agree with the VFD as likely the most convenient and least expensive remedy overall, assuming you can find a match for the 575V operating voltage. Second choice would be direct replacement motor single-phase 220v version, but you will then be faced with mucking around with the contactor and heaters, to match all that stuff up. I would avoid down-rating the HP as a personal choice, just because you always need more guts in a table saw.
 
How could i test the motor with no 3 phase. And where is a good basic beginners place to start to learn how to wire a VFD if i was to go that way?
 
How could i test the motor with no 3 phase. And where is a good basic beginners place to start to learn how to wire a VFD if i was to go that way?

There is a forum on this website devoted to phase converters and VFDs; lots of info there. And the typical VFD comes with lots of instructions.

As far as testing a 3-phase motor with no 3-phase, the previous suggestion of using a static phase converter is something to look into, as well as using it as the poster suggested, to run the saw on an ongoing basis.
 
He said the original motor is 575v making it a poor candidate for a VFD (as best as I can understand, it is hard to change the input voltage with a VFD.

Be wary that the older motors were slower speed with a larger pulley, so if you find one of those it may not match your pulley size.

I like a 3hp minimum for ripping 8/4 hardwoods. But if you are not working such materials, you can probably get away with less.

Pete
 
Man........a static phase converter is so cheap and so easy. The slight loss in HP will never be noticed on a hefty saw like a Delta. Hate to keep beating my drum but it really is a super simple answer to the OP's conundrum..unless I'm missing something obvious, which I've been known to do.

Stuart
 
Man........a static phase converter is so cheap and so easy. The slight loss in HP will never be noticed on a hefty saw like a Delta. Hate to keep beating my drum but it really is a super simple answer to the OP's conundrum..unless I'm missing something obvious, which I've been known to do.

Stuart

The fact that his existing motor is 575v MIGHT be the point you are over-looking........
 
Joe Bergamo at Plaza machinery had Leeson make a batch of 240V single phase Unisaw motors for him. Not sure what happened to Plaza machinery (his site) after his son took over. Doesn't seem to be a website easily available now.

I bought one from Joe for a friend and installed it. Worked perfectly, but the motor diameter was considerably larger than the 3 phase motor it replaced. Some sheet metal removal was necessary....:D

One could find the single phase motor of choice and weld the old brackets on. Going slow, with rests between welds, would ensure that the laminations wouldn't heat up. Could also do the same to another 3 phase 220V motor....
 








 
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