Unisaw getting a single phase motor - issues with new motor...

[Bradley J Jones]

Hello all,

I have finally arrived at the motor install stage in my rebuild. Not a complete restoration but a new arbor bracket, refurbished arbor itself and a new worm gear for arbor bracket adjustment were all installed.

Now, I purchased this as a 3ph unit, knowing i would do a conversion and not giving a VFD much thought due to much ignorance. Now, after fully unboxing the 1ph motor I fleabayed - there are some major differences that I'm seeing after putting them next to each other.

First, the bracket mounting holes are opposite each other - meaning the "pivot" holes and "radius'd slots" are opposite. You can't see, but the motors are oriented the same way on the table top.
http://i.imgur.com/bzbMLesl.jpghttp://i.imgur.com/dMsBT4Gl.jpg


The second issue - the mount brackets are at least 4" different between the old motor and new. On the old motor, the bracket to shaft end of motor is roughly 2". The new motor, that same distance is just over 5 1/2". Thats a lot of difference which would not allow the motor/arbor pulleys to line up.
http://i.imgur.com/EoAaHVNl.jpghttp://i.imgur.com/ryJqaA8l.jpg



Does anyone know if right and left tilt machines received different motors? I have a right tilt machine and am wondering if I received a left tilt motor?

If anyone recognizes this motor it would be awesome to know what it would go to so that I know how to market it if I need to sell it to get a new motor or even a VFD now that it looks like I'm stuck in the water...

Thanks in advance!!!

[Bill Adamsen]

Your suspicion on the right tilt versus left was the first thing that crossed my mind. I feel your pain.

You probably already know this, but the bracket to front dimension (BA) in NEMA for the 145 frame varies between 2-1/4" and 2-3/4" so that ~5" is definitely not a 145 or 143 (Unisaw) frame. Does it by any chance have the frame specification on the motor?

http://www.engineeringtoolbox.com/nema-electrical-motor-frame-dimensions-d_1504.html

Crazy thought - any chance it is rebuilt and they mounted the arbor and ends backwards?

[Bradley J Jones]

That is definitely not a crazy though!!. I've never ripped into a motor but I'm guessing that's a strong possibility. That seems like it would solve both problems If I could tear it down and rebuild it the opposite way...



Crazy thought - any chance it is rebuilt and they mounted the arbor and ends backwards?

[John McClanahan]

The single phase motor have a start winding switch at one end. It is not possible to put a motor together backwards that will run. I noticed the mounting bracket is rotated 180 deg. too. I think you one correct about the right tilt left tilt.


John

[Bradley J Jones]

So, theoretically, the motor is currently assembled wrong, which would mean that I could disassemble and reassemble correctly and it could work.

I suppose I could go ahead and bench wire it to test if it works in the current configuration...


The single phase motor have a start winding switch at one end. It is not possible to put a motor together backwards that will run. I noticed the mounting bracket is rotated 180 deg. too. I think you one correct about the right tilt left tilt.


John

[David Kumm]

I think it is unlikely the motor is assembled wrong. It is common for companies to spec motors with special mounts or some slight changes to make their assembly process easier and to provide for an aftermarket need. The three phase motor looks to be a better quality unit. I'd spend 150 for a vfd and keep the old motor. Dave

[Joe Kaufman]

I don't know the differences in the motors between right and left tilt unisaws. However, It is possible that the stator (frame) of the motor could be switched end for end in relation to the end bells and rotor assembly. I would first verify that it would physically fit. Place motors pulley to pulley and tape cardboard copies of the capacitor and wiring junction box to the 3 phase motor and reinstall if necessary. Check if all windings are terminated in the junction box and there are a couple of slots in the stator that are open to run the starting coil leads to the centrifugal switch since it is now at the opposite end. There are a lot of if's and could be a little work, or it you could end up with an unuseable motor. A lot depends on your interest and skill level.

One important factor, the stator to rotor must be in alignment, the center of the stator must to be equidistant from the ends of the sheet metal outer shell. Internal fan motors are generally not, looks like yours is external.

[Dave Cav]

I think it is unlikely the motor is assembled wrong. It is common for companies to spec motors with special mounts or some slight changes to make their assembly process easier and to provide for an aftermarket need. The three phase motor looks to be a better quality unit. I'd spend 150 for a vfd and keep the old motor. Dave

I'm with David on this one. And I don't think the single phase motor was assembled backwards, due to the centrifugal switch location, as mentioned upthread.

[CPeter James]

That is definitely a left/right issue. One reason the motor can't be changed to the other way is that the field windings come out one end of the center section. Get a VFD and be happy. Soft start, smoother running and noting to go wrong in side except replace the bearings every 25 years.
CPeter

[Bruce Wrenn]

If ebay motor is not returnable, cut the brackets off and weld them where they need to be. Does motor turn in right direction?

[Patrick Curry]

If ebay motor is not returnable, cut the brackets off and weld them where they need to be. Does motor turn in right direction?

Welding was same solution I had in mind.
I have a couple of 3hp motors in storage- a nice new Baldor and one off a Grizzly jointer. My intentions are to install them on 3ph industrial equipment like a cabinet saw when one comes along at the right price.
Modifying the mounting brackets to fit the machine is the plan