36-L352 Unisaw

[John Pratt]

I have been using my new unisaw daily for a couple of months now and I ran into a problem that I cant figure out (called Delta but no answer yet). Does the motor have an automatic cutoff or heat switch? While cutting a 3/4" dado 1/4" deep (Freud SD508) in a 12' piece of red oak, the motor just stopped. It did not trip the breaker at the panel but the machine did not respond to the on/off switch. After scratching my head for about a minute the machine began working again. It did the same thing on the next piece of the same size. After another minute, it began working again and has worked fine on every cut since. The motor did not sound as if it was under stress at the time and the blades were spinning at full RPM when the shut down happened. Other than this dilemma, I have been extremely happy with this saw and how it performs (with the possible exception of average dust collection). I stumped with this problem, any ideas?

[mark kosse]

I don't have much new equipment but to my knowledge a thermal overload has to be manually reset, much like a tripped breaker. It sounds like it may be an internal short, but that would be a guess.

[Jim Dunn]

Thermal overloads can automaticly reset as soon as they cool down enough.

[Josiah Bartlett]

Does this saw have a magnetic switch? Those have been known to go bad or stop under certain vibration conditions.

[John Pratt]

Thermal overload switch sounds plausible. It does reset itself in short order and then the saw seems to work fine again. I just didn't think a 3/4" X 1/4" dado in Red oak would be enough to trip it. Of course the board is 12' long so that is a considerable amount of time under load. Maybe I should have splurged for the 5hp.

[mickey cassiba]

Although this model came out long after I left B&D,PCDelta or whatever they are now, the problem sounds like a common one we had some years back.
The Magnetic starter switch was losing its connection(magnetic attraction) and allowing the contacts to open, although it would start immediately when the start button was pushed. Not sure what motors are in the new models, WEG and Emerson were both used in the models I worked on, and there was no reset button...but they generally took longer than "a minute" to restart when overheated(thermal trip).
Try smacking the starter box sharply while the machine is running, without a load. Use your hand, or something softer than a hammer. If the machine shuts down, the likely culprit is the mag switch.
Regardless of the problem, the machine should be in warranty, and we used to make "house calls" for machines of that size and weight.
Mickey

[Chris Rosenberger]

Thermal overload switch sounds plausible. It does reset itself in short order and then the saw seems to work fine again. I just didn't think a 3/4" X 1/4" dado in Red oak would be enough to trip it. Of course the board is 12' long so that is a considerable amount of time under load. Maybe I should have splurged for the 5hp.

The new Unisaws have Marathon motors.
There is an adjustable overload inside the switch box. It should be set at about 14 amps for the 3 hp motor. If the overload is set at the correct amperage, then it could be that the overload is bad, the motor could be bad or you could have low voltage causing the motor to overheat.

Chris

[Chip Lindley]

Good suggestions above, as to where the problem may be. IF the motor includes an automatic overload that opens and resets, you should hear a faint click when it closes back to normal. A manual reset button would have to be pushed by hand.

Bottom line is, your brand new Unisaw should not kick it's overload by simply using a dado blade in hardwood. It should have BUTT to spare! The new saw is under a nice warranty. USE IT!

[John Pratt]

Thanks for all the replys. Mickey, I enjoy your insight especially since I know how you feel about Delta. Thanks guys. It's off to try and get in touch with Delta again.

[Chris Rosenberger]

It's off to try and get in touch with Delta again.

Good luck with Delta Service. I spent 45 minutes on the phone with them last week about a problem with my Unisaw. I talked 3 different people & was on hold to talk to a 4th when I gave up. I took care of the problem myself.

[Julian Wong]

John, My uni (WEG motor) draws slightly under 13A, and the overload limit is set for 15A. I have a thermal overload switch located inside of the magnetic switch. There is also a selectable current limit in there. My uni (WEG motor) draws slightly under 13A, and the overload limit is set for 15A.

If your current limit is set for 13A, it may have tripped because the fluctuations in current draw may have exceeded 13A while doing a dado.

I have not seen the newer switch for the new uni, but I would assume there would be a overcurrent switch inside the mag switch like mine.

[John Pratt]

Just an update...

Got through to Delta first thing this morning. Three minutes on the phone, three minutes on the saw and the problem is fixed. Thanks to all who suggested the thermal overload. That helped in explaining it on the phone. Tech said to adjust the thermal overload in the magnetic switch. It was set on 12 amps for the 12.4 amp motor. Turned it up to 14A on their recommendation.

[Chris Rosenberger]

John, I am glad it was that simple.
Enjoy your saw.

[Sean Nagle]

John, great news that it was a simple fix. Do you mind providing a bit more detail and maybe a picture or two in case others run into the same issue? I had my Unisaw shutdown like that just once many, many years ago [but never since]. I'm sure it was the magnetic switch.

[John Pratt]

John, great news that it was a simple fix. Do you mind providing a bit more detail and maybe a picture or two in case others run into the same issue? I had my Unisaw shutdown like that just once many, many years ago [but never since]. I'm sure it was the magnetic switch.

For the problem stated above the fix was just taking the cover off the magnetic switch (on/off switch hanging on the front of the machine) and turning the adjustable thermal overload switch. When the cover is off the switch it is the dial that show the amperage much like a temp setting on a water heater. One twist with a screwdriver and done. One caveat, not all magnetic switches have this adjustable thermal overload dial. The Tech from Delta told me that they don't always put in the adjustable ones and it varies year by year.