I recently wired up my father’s older Rockwell 2 HP Unisaw, circa 1980 (?) to use in my basement, for some cabinets I’m building for myself. Ran fine for a couple dozen cuts and then ceased to work. There is juice to the saw but the blade does not turn, just sort of idles there, humming and ultimately trips the breaker. I’ve seen some other similar posts but wondered if there is anything unique to this saw I should know about? I gave everything a good douche with the air and tried it again, also found a loose wire in the back but still nothing at this point. Thanks.
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Presumably this an AC motor vs AC/DC motor (ie, one with a comutator)?
If AC then likely it has a starter switch that is failing to close when the motor is not turning. This is a centrifugal switch inside the motor -- you likely hear it click as the motor slows down after you turn it off.
Try blowing air into the motor itself, at both ends. (The start switch may be on either end.) If you can identify the start switch you can try activating it with a piece of wire through the vent opening (unplug the motor first!), on the assumption that sawdust has gotten into the contacts.
The other possibility is a blown start capacitor.
What Dan said.
Whatever you do, hold onto that saw; it's worth fixing.
Are you sure it's a Unisaw made by Rockwell? I've got a 1960's vintage, which is one of my favorite tools, but I thought Rockwell changed to Delta in the 1970s. Maybe I'm wrong, or maybe that saw it older than you think.
Also, the Unisaw is usually equipped with a 3hp 240V motor. Has it been changed?
Thanks to both for replying...I'm still troubleshooting here.
I was wrong about the HP-it is in fact a 3 horse Baldor motor. But built in Pittsburgh, circa 1980, model # 34-761.
I'll keep you posted when the repair is complete.
If you can't puzzle it out, you should remove the motor and take it to a local motor shop.
The capacitor seems to be the issue; one of its wire had broken the solder and arced. Must be a lot of vibration, as there was also a wire loose in the electrical box in back. Going on 35 yrs, I guess we should feel lucky to have it run so well for so long. Luckier still to find a replacement for $15, an hour's drive away. We'll throw the new one in tomorrow and fire it up and see if that was the problem or just a symptom of something more substantial (and expensive). I just need to get through the cabinets and then the old girl can do what she wants. If you don't hear from me, we're cooking with Crisco. Thanks again.