Unisaw motor/switch replacement question

[Gary A Smith]

I purchased an old (1954) Unisaw with an inoperable motor. The motor was a fairly new replacement Leeson 2hp. I was hoping that the motor problem was minor - a capacitor or contacts. It turns out that the motor is burnt. So, I have two questions that I would appreciate any thoughts on:
1) The incremental price differences on ebay between 2, 3, and 4 hp Lesson Unisaw motors is relatively minor. Is there any reason a 3 or 4 hp would not fit on this saw?
2) I think that the reason the motor is burnt is that the switch on the saw has no thermal overload protection. Looking at the switches available from Grizzly, the magnetic switches (about $70) state that they have overload protection, the less expensive switches (about $12-15) do not. Do I have to get the magnetic switch to have the thermal overload protection? If not, what other switches are usable that have the overload protection?
Thanks very much for any reponses/recommendations.

[Mike Reinholtz]

I rebuilt an older unisaw last fall and went through a similar debate. The newer motors available can run into a problem where they hit the motor cutout on the side of the saw. Some people (like those at OWWM) freak out at the idea of cutting the cabinet to allow a newer style motor to fit. I cut mine, installed a single phase 3HP motor and never looked back. I didn't get a motor cover with mine, so I ordered a plastic square one off ebay that is oversized to fit new motors (even covers the cuts I made to the cabinet. Beware though the metal is thick on these cabinets and it takes a little work to cut. It wasn't too bad for me, I used a jigsaw and with the right blade the cut came out pretty good. I stuck with the 3HP over the 5HP because for one I didn't see a need for the added power and two I only had a 20 amp outlet feeding it- a 5HP motor needs 30 amp service. So far I haven't had any issues with power even when I cut dadoes or use a full kerf glue line rip blade on 12/4 maple.

I still have the 3 phase motor the saw came with, it collects dust in the corner waiting for someone that could use it.

[Chip Lindley]

A shame the newer Leeson got Fried. It's hard to believe a Unisaw 2hp motor was overworked to that point. But, in the hands of some, anything is possible.

On ebay:
Leeson 4hp, 17.6A $529.88
Leeson 3hp, 13.0A $498.53
Leeson 2hp 11.0A $397.80

Ouch!

It is duely noted that there is some added efficiency in newer electric motors, but I wonder also if there is some selling hype here. My '90s Leeson 3hp Unisaw motor pulls 16A. My Powermatic 66 3hp Baldor pulls 15A. If you have the bucks, go with the biggest Leeson offers now.

Of course, you could always pull the saw's 3-phase motor out of mothballs and look into using a VFD with it. You might save some big bucks going that route.

Yes, your cabinet's motor opening will have to be enlarged to tilt/raise these larger motors. I can provide exact measurements of the later-style Unisaw cabinet opening which accepts up to a 5hp motor if you are interested. I did the surgery on a '47 Unisaw several years ago to allow use of the 3hp Leeson.

As for overload protection, if you are not worried about keeping the Unisaw OEM, look for a Square D mag starter on ebay. These are usually available at a reasonable price.

Model 8536
Size 1 (30A rating)
Single-phase
115v/230v coil
enclosure with start/stop buttons

http://i822.photobucket.com/albums/zz142/zzarus/SqDEnclosure.jpg

A single overload heater will be needed to match your motor's full-load amp rating;

17.6A = B25
13.0A = B19.5
11.0A = B17.5

Otherwise, a Rockwell/Delta single-phase LVC starter is what you would be looking for. These are pricy and less easily found.

http://i822.photobucket.com/albums/zz142/zzarus/RockwellLVC1-phase.jpg

The LVC will also need a momentary-type on/off pushbutton station to function.

http://i822.photobucket.com/albums/zz142/zzarus/LVCPushbutton.jpg

[Gary A Smith]

Thank you both for your helpful responses.:)