Fried Unisaw?

[Tom Watson]

This afternoon I got a piece of ply jammed in my Unisaw. I got to the switch before the breaker tripped but when I restarted the saw the blade turned very slowly and then the breaker tripped.

The motor was not warm to the touch and there was none of the burning smell that you would usually associate with a fried electrical part.

I'm hoping that the contacts on the centrifugal switch are a little burned and will respond to some cleaning but thought I'd ask if anyone here has had a similar problem before and what their thoughts might be.

These motors are expensive, so I'd be willing to put a bit of time into trying to fix this one.

(As a backup - who has the best prices on replacement motors?)

Thanks.

Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[skeezics]

others. none of em are cheep!!!!!!!!!!!!! 3 hp motors are reasonable BUT the ones with the right mount and the 3/4" shaft cost ya double. skeez

[Unisaw A100]

Plaza Machinery has Baldor 3 horsies for $335.00 plus $15.00 shipping. Leesons run $299.

[George]

After you get the blade out of the picture, see if it works after you spin it. Could be a shorted capacitor.

Probably better to rebuild than repurchase.

[Robert Galloway]

Good advice. Can't cost more to fix than to replace unless you've actually fried it. Your description of running slow doesn't sound like fried.

rhg

George wrote:

[George M. Kazaka]

Tom Is it 3 phase??? and if it is do you have it fused???

You could of blown one fuse, Or yes you could of burnt one of the heat couplers, Either way you won't get that burning smell and of course that why those things are their to protect the motor.

Good luck let us know what you find George

[Tom Watson]

No, it's a 3hp single phase 220v model 83-651 with a 145ty-95 frame.

Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[Lew Hodgett]

I know the Unisaw uses a custom motor, but I must profess my ignorance as to it's configuration.

Does this motor have a run cap as well as a start cap?

Your description fits a problem you would expect with a cap start, cap run, motor.

HTH

[Swingman]

My Unisaw did the same thing once, complete with slow down. Came back a couple of hours later to start taking it apart and it came up running and has never balked again. I wish you the same luck.

[George M. Kazaka]

If you have no fuses in the wiring, look for the thermal protectors in both the switch, and that connecter box that is usually on the back of the saw.

I have never had the problem of thermal protector in the motor itself but if all else failed i would certainy look.

I've been known to lock up my unisaw a time or two or three, Its never shut down on me, But I have had the thermal protectors go on other 3 phase machines. My compressor is 3 phase and it is also fused as well as a circuit breaker and I have blown a fuse on that several times.

When you throw one leg on a 3 phase circuit some motors will do like you said run slow, and some will just sit there and humm.

I doubt you blew the Motor unless that sucker is real old and tired, I have 5 horse that is about 15 years old, and still chopping wood without tiring. I'm willing to bet its in the wiring systen someware as in fuses or thermal protectors I'll look at my wiring diagram when i go into the shop in the morning and see where it could possibly be.

Good luck, George

[Larry Jaques]

On Wed, 22 Oct 2003 16:26:51 -0400, Tom Watson pixelated:

Wood a 3 or 5hp HFT for $69.99 do ya, Tawm? 2hp for $60, too. That Ewenisaur deserves no less!

Or have yours rewound for a benjy if it's not a cap/points. Your call.

- Metaphors Be With You -

Web Application Programming

[todd]

weekend to dispose of it in an enviromentally-safe manner. ;-)

Seriously, I'm with most thinking that the problem is outside of the motor. However, if it ends up needing replacement, I replaced a 3-phase motor in my DJ-20 (1.75HP) with a single-phase job about a year ago. I tried going the route of finding a motor shop with a used motor. I called three or four places with no luck. I was also told that no one wastes their time rewinding motors under 10HP...YMMV. After a lot of looking, I ended up finding a motor at my not-so-nearby Farm and Fleet. It was actually made by the same company that made the original for Delta (Marathon Electric). I don't know how high a HP rating they carry, or if they carry it in the frame style you require.

I was also given recommendations to check out

Good luck, todd

[Steve]

I had nearly the same thing happen while resawing a large peice of wood. The saw quit running and after a day would still not power up. I opened the switch and pushed the start buttong with thecover off and now it works fine. I have no idea why but I suppose the switch had some kind of protection and just needed to be pushed all the way down which can't be done with the cover on.

I do realize this sounds almost dumb, but it worked and no problems since.

[Tom Watson]

Yeah Lew, it's a cap start/cap run. In the morning I'm going to check the starting cap and the centrifugal switch.

Delta's motor is custom in that it has that funny mount on it, and the shaft length and thickness are non-standard.

I'm hoping their capacitors are not proprietary.

Regards, Tom. Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[Lew Hodgett]

From you description, sounds like the motor has sufficient starting torque but does not maintain speed.

That would lead me to suspect the run cap, not the start cap and switch.

Your local Grainger will have caps in stock, probably at the regional whse, available within 24 hours worst case.

HTH

[Tom Watson]

Grainger has caps of the right specs but not the right form factor. They have mostly oval shapes and these are cylinders.

I couldn't find my meter and so I took the caps to a local shop to have them tested. Tested good.

Tomorrow AM will look at centrifugal switch.

(will also buy new meter - sigh)

Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[Norman D. Crow]

Tom, Doncha just hate it when objects like that grow legs and walk away?

Thought I'd chime in on the motor though. Went back to the beginning of the thread, and I'd be willing to bet(Oh, maybe 25 cents or so) that when the saw jammed, the centrifugal starter switch welded itself shut. Now, instead of spinning up and opening the start winding, it's trying to run on both windings, which is causing the slow rotation and the breaker opening. I'll bet it's making a rather loud "growling" noise too. Just my $.02 Nahmie

[Lew Hodgett]

OK, time for plan B.

You will need a means of testing for continuity.

Before taking the motor apart, chuck up the shaft in a drill motor, say

1,100 RPM minimum, 1,800 would be better, and do a continuity check across the switch leads now that the caps are removed.

Start the drill motor. If you loose continuity, mech switch is OK.

If switch is OK, start chasing loose connections which will be sort of like chasing smoke.

HTH