Unisaw power switch question

[Dave Manley]

I have a Delta Unisaw 34-761. The power switch is the pushbutton switch side by side with a thermal protector (Klixon 09 T7C BET44DA-2). The terminals on the thermal protector were soldered poorly by some previous owner and I cannot get solder to join with the nubs that remain. I cannot find a replacement.

I freely admit that I am not clear on "Magnetic Switch" vs "Starter". I hold down the green button to start the saw - If I release too early, it will not stay on. Motor is a Rockwell 83-621. 1.5HP wired for 220v, 9.6a. When I got the saw at auction, the cord was removed. I checked the wiring, and it was per diagram for 220v, I replaced the cord and it worked fine. I did notice that the wires in the switch box were in poor condition - frayed, electrical tape falling off, some conductors at the back of the thermal protector were broken. I decided to replace them. They appear to be originally crimped.

I like the Grizzly H8242 style switch but I don't think it has thermal protection.

This seems more correct, but I wish it had the paddle shut off. (Grizzly T24104 if I did the link correctly)

My first choice is to just replace the thermal protector. I emailed Klixon to see if they offer one but have not heard back and can't find a cross on their web site.

Second choice is to get a paddle mag switch. Do I need to add a thermal (I think so for motor safety)? Is there an obvious choice to buy?

Or - just get the Mag switch with thermal and normal push-buttons?

This is the back of the switch plate. Red wire was connected to a wire on the protector. It broke off. Crimp nubs on the protector will not take solder. No sawdust for me until this is fixed......

IMG_3961[1].jpg

[George Makra]

The difference between a contactor and a starter is they are the same except the starter will have overloads.
The thermal cutout is similar (not identical ) to an overload.
If you go the starter route be prepared to lay down some money for a paddle switch, transformer, and contactor with overloads and a can to put all this in.
I have been involved with electricity for many years and I cant recall seeing a single phase starter, not saying they dont exist I just dont recall seeing one.
Look up what a 000 or 00 size starter will set you back.

One other idea that could be less expensive is to put a fuse block off the bottom of the contactor.

[Mike Wilkins]

The paddle-style switch from Grizzly should work for your application. If you look at some of the modern-day table saw offerings, that is the type of switch they are supplied with. I did a similar switch for a Unisaw I used to own. You could also find a magnetic switch from Grizzly as well.

[David Pascoe]

I got my replacement direct from Delta Machinery.

[David L Morse]

The Grizzly starter you referenced (T24104) would be inappropriate for the 9.6A rating of your motor since it can be adjusted to no lower than 15A. The T24100 or G4572 would be a better choice. You could add the paddle switch as an emergency stop if you don't mind hitting it's "on" button as a reset before starting at the starter. Just wire it in series with the "Stop" button on the starter.

FWIW the Klixon device you have is over current protection. Actual over temperature protection uses a sensor embedded in the motor windings. The "thermal" part of it's description refers to fact that it uses self heating to accomplish a time delay before tripping, just like the circuit breakers in your electrical panel and the heaters in a motor starter.

[Mike Goetzke]

Would something like this work for you?

ebay item # 302176557661

[lee cox]

I have a Unisaw. I am trying to understand this thread. My Unisaw has a 24 volt mag start Delta system for a Rockwell 3HP single phase motor. So is the difference between a "magnetic switch" and "Starter" just the difference between low voltage start and full voltage start? You guys got a little advanced for me.

[mark kosse]

Lee, A mag starter won't restart after a power failure because the controls have dropped back out. A starter is manual so if it is the on position it will start when power is applied. This doesn't matter so much in a home shop but in an industrial setting auto restart could cause problems.

[David L Morse]

I have a Unisaw. I am trying to understand this thread. My Unisaw has a 24 volt mag start Delta system for a Rockwell 3HP single phase motor. So is the difference between a "magnetic switch" and "Starter" just the difference between low voltage start and full voltage start? You guys got a little advanced for me.

The 24V you refer to is just the coil voltage of the contactor. That can be 24 or 120 or 240 or something else. Coil voltage doesn't affect the name.

The terms "Magnetic Switch", "Magnetic Starter" and "Motor Starter" are sometimes used interchangeably to indicate a latching type contactor (relay) that uses momentary contact switches for control. More often "Starter" is used in the name when overcurrent protection is included. So "Magnetic Switch" would indicate a latching contactor without a circuit breaker and "Magnetic Starter" includes a thermal time delay circuit breaker, sometimes called "Heaters".

Really big motors need a box full of equipment for a safe start and that's really where the name "Starter" comes from since just applying full voltage won't work.

In the OP's case his switch appears to be a self contained magnetic switch. The contactor and control switches are all inside the plastic housing. The Klixon device provides the overcurrent protection.

All of these devices provide the desirable feature of not restarting upon reapplication of interrupted power.

[Larry Komroff]

Have you tried brushing the area to be soldered with flux. That usually cleans the metal so the solder will stick. There is also the option of replacing the (Klixon 09 T7C BET44DA-2). I found it at http://www.carbonbrush.com/klixonBE.htm The model you are interested in is at the bottom of the drop down list. Not inexpensive though

Larry