Unisaw switch: reset button purpose

[Brandon Davis]

I need help with understanding the "reset button" part of the switch on my Unisaw, and what it's for (and whether to just replace the whole thing).

Backstory: I finally ran 230V to my garage this past weekend, and rewired my 1975 Unisaw (Model No. 34-476) to 230V.

The motor is a Leeson 1.5 HP (Model No. 83-621) and is likely a mid-1980's replacement of the original motor. The switch(es) were probably added at that time?

Here's pix of the switch and reset button and the wiring:

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I pretty much understand how a simple start-stop switch should be wired IF there wasn't that reset button (well, I found diagrams that I could follow ...and I'm inclined to change this to a Grizzly start/stop paddle switch regardless).

But I don't understand the reset button "addition" to the switch arrangement. I don't know what it's for, or if it's even necessary (I found pix online, but they weren't any help as to function and purpose). Is it really useful? Would it be okay to just take it out altogether?

Can someone point me in the right direction here?

[Andy Booth]

The thermal overload switch is intended to protect the motor from overheating due to overloading the motor for extended time.
Current x time = temperature rise in motor.
Too much current for too much much time and the motor can get hot enough to damage the insulation in the motor. Worst case it can catch fire.
Thermal overloads protect the motor against slow overheating.
This can happen due to a blade binding in a motor or just pushing wood to fast for too long.
The thermal overload can be reset after a motor cools down.

You need it to protect the motor and should not remover the thermal overload.

[Brandon Davis]

Thanks Andy. That makes sense.

...something in the wiring to the switch and/or the reset button isn't right.

The motor was wired for 115V when I bought it (I've never used the saw, other than running it a few minutes to test it: it ran fine).

This past weekend - following the diagram on the motor - I rewired the motor for 230V. It starts and runs at 230V as it did at 115V.

But I just noticed the longer its plugged into the [230V] wall socket (and even when not running), the warmer the case gets.

I didn't make any changes to the switch or reset button wiring.

I will be, now.

Looks like I have some more googling to do.

[Brandon Davis]

I found this picture of a wiring diagram for the Klixon thermal overload protector.

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I see from the Klixon diagram that the thermal overload reset switch is wired different for 115V and 230V ...which explains the motor case getting warm?

Can anyone translate this from Electric to HowTo (i.e., from symbols to "connect these [colored] wires")?

Here's the motor wiring diagram:

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It's currently wired for 230V.

Any help at sorting this out would be vastly appreciated.

[David L Morse]

The paper diagram pasted to the motor shows the proper connections. Can you open the junction box on the motor and take a pic to show how you rewired it?

[Larry Browning]

That's for when you realize you cut a board 1 inch too short. Press the reset button, adjust the fence and cut it again! Sadly, my saw doesn't have a reset button.

[Brandon Davis]

The paper diagram pasted to the motor shows the proper connections. Can you open the junction box on the motor and take a pic to show how you rewired it?

Thanks David, and I will in the morning.

But it will be pix of the corrected wiring, after my brother and I puzzled it out late this afternoon.

Yep. Problem solved. On to the next.

[Brandon Davis]

That's for when you realize you cut a board 1 inch too short. Press the reset button, adjust the fence and cut it again! Sadly, my saw doesn't have a reset button.

Heh.

I only wish.

:D

[Brandon Davis]

This is just a follow-up and conclusion to my Unisaw switch problem (just in case anyone else needs the info in a simple format).

This is the pix of the switch my Unisaw came with:

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I suspect the [Furnas 12BA21T] switch and the [Klixon 09 T7C BET44DA-2] thermal overload reset was a stock switching option with the c. 1984 Unisaw 34-801 that a previous owner used - along with a Delta model no. 83-621 1½ HP Leeson [/Marathon] motor - to replace the original motor on my c. 1975 model 34-476 Uni' (seems likely at least).

What confused me at first was the red wire in the motor-to-switch 4-wire cord. When we (my baby brother helped) puzzled out that the red wire wasn't necessary, what-connected-to-what finally made sense. (And of course, after we were done, I found a thread online that mentioned the red wire was used with a 3 phase motor ...which is why I'm guessing there's now a c. 1985 single phase [replacement] motor in my 1975 saw.)

Anyways, in case anyone else can use the help ...here is a simple-to-follow wiring diagram for wiring an 83-621 motor to 230V (sorry, it's kind of small).

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In case it's not entirely clear, here's a written description. NOTE: The BET44DA-2 had soldered terminal wires (so I ignored the color inconsistencies).


The motor is wired per the diagram on the motor (pix in previous comment); wires are connected as follows...

Black-to-black (hot) to switch box
Brown-to-white (hot) to switch box
Green-to-green (ground) to the common ground screw in the switch box
Red-to-Yellow (internal only)


From the 230V wall outlet

black (hot) goes to a LINE side screw of the 12BA21T
white (hot) goes to a LINE side screw of the 12BA21T
green (ground) goes to the common ground screw in the switch box


Connect the black wire from the motor to the LOAD side of the 12BA21T (black-to-black to keep color code consistent)
The white wire LOAD side screw is connected to the No. 1 terminal of the BET44DA-2 (via short black wire)
Connect the [short] red wire from No. 3 terminal of the BET44DA-2 to the white wire coming from the motor. NOTE: The No. 2 terminal of the BET44DA-2 is tied-off and not used.


And that's it for 230V wiring.

These are pix of the actual wired switches, and the actual wiring of the motor. (Notice the red wire is tied-off at both ends.).

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I've included pix of the Klixon protector and Furnas switch "just in case".

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...during the course of this project, I found several other things with the Unisaw that will need looked at too. I'll have other threads for those questions.

Thanks again.