Delta Unisaw 3-phase

SDMike

Member
I have been looking for a replacement table saw. Delta's Unisaw seems to be decent from what I have read. Have found a couple in the $500-$750 range. Most are 240 3 phase machines.
Is there a way to convert the 3 phase to single ? Would it be more economical to replace the motor ?
Thanks
Mike
 
Use a variable frequency drive to convert single phase to three phase.
If it's a 1HP motor, use a 2HP VFD.
VFD are dirt cheap on eBay. They are quiet , efficient and take up little room. It will also let you use other bargin three phase equipment.
Some people will sing the virtues of a rotary converter with a starter rope wrapped around the shaft . There was a time in the dark days of the ancient past when a rotary converter or a Motor generator set was the only option . Things are different now in 2014.
 
It would more than likely be cheaper to replace the motor. a three horse unisaw motor will run under $600 dollars.
 
I've been using a dummy motor, kick-started with a chain gear, very happily for the past 25 years. See no reason to change for my shop full of 3 phase machines, including my Unisaw. $5 for a used 3 phase motor (5 hp) strikes me as reasonable.

VFDs are cheaper?
 
The biggest difference between a VFD and a rotary converter, is that the VFD can only be used to run one piece of equipment at the time, just like a static converter. The difference in the static and VFD, so I understand, is you don't lose 1/3 of your available power when using the VFD like you do with a static setup. If you run a rotary converter, you don't lose the power, and it can be used to run multiple machines all at once. Too, as each new motor is started, it acts as an idler also, basically increasing the potential output of the system.

As a for instance, Dad had one in his shop capable of starting a typical 10HP motor. On cold days it didn't have enough power to start a 7.5 HP air compressor against the friction of the cold oil along with the compression of the compressor. To that end, on cold mornings we began by starting the lathe, which had a 5 HP motor and was under a very light load. With it running, the starting potential of the system was increased, and the compressor would start right up with no problem.

Again VFD, good for someone with only one piece of equipment, but rotary good for many pieces of equipment. Personally, for no more than the components cost to build your own rotary converter, and I have one I built that easily runs a 5HP mill and 5HP lathe at the same time, a person would have to be crazy to spend the money to buy not one, but two VFD"s to achieve the same level of service. Granted this guy is only looking for a way to run one motor, but with the lower cost of 3 phase machines, why not go ahead and make it to where another machine can be added at a later date, without any additional cost?
 
You are right about things are different in 2014.
Probably the first time in history we could be living like it was 1914 in 3 days.
I like my self exciting rotary phase converter with off the shelf parts. But I do admit to owning 2 Chinese VFDs. If they quit working, probably will just throw them on my junk(spare parts) pile.
ps I read and like you posts; keep them coming.
 
I would vote for swapping the motor. Simple, one-time fix.

Sell the 3ph motor and get some cash back. You could also call a local industrial motor supply house and see if they would be interested in swapping.

I have a manufacturing plant and the 3 phase motors always seem to be at a premium.
 
Bob, the Unisaw motor I have and all the ones I've ever seen don't fit anything else. Not a standard base. That's one drawback to Unisaw, but they sure work well with a good fence.

Last I checked, swapping would add $400 to the cost of the saw. More than a lot of us saw any reason to spend.
 
Good point about multiple tools Wayne. I frequently use my 12" jointer in combination with my Unisaw, both 3 phase.

I started out with a static converter, which would start several tools at once. The older 3 phase tools worked OK, but newer ones ran very hot. Maybe the wire in the motors was smaller. It was my new Unisaw that caused us to experiment with rotary converters. Wouldn't work very long even by itself on a static converter. Thermal protection is good.
 
I found quite a few 3 HP Leeson #120728 Unisaw Motors for $300-500 online. Mine has a 3HP Baldor in it. I know the Baldor WWL3606 used to be widely available for the Unisaw. You might be able to find one somewhere.

I think it is going to be a tossup as to whether the VFD or Motor replacement is cheaper.

If the Unisaw is older the motor may turn slower than the modern motor. You would need to buy a replacement pulley and belt for the higher speed motor also.

HTH

Cliff(VA)
Replacement Leeson Motor
 
You must be looking at a used saw. Most new $750 saws will not be 3 phase. There are many 220 volt single phase unisaws for sale. Skip the phase convertor, replace the motor if you have to and make sure you have a modern fence and good guard. If by chance you are looking at a new saw, I would seriously consider the Saw Stop brand saws with the safety feature that prevents most table saw related injuries. I have a small cabinet shop and have had one of these saw for about 8-10 years. I feel a lot safer when using this table saw also when my 17 year old son or any employee uses it. The higher cost is easily offset by even one trip to the emergency room. I can't post a link but google "Sawstop" and you will find their website, great company to do business with. Anyway the old saws are still a good value and parts are available to rebuild even a wore out saw, I do still have a Unisaw still in use built I think in the '50's and performs well. Johnny
 

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