Replacement Table Saw Magnetic Switch

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rmac
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Replacement Table Saw Magnetic Switch

Post by rmac » Thu Jul 08, 2021 9:50 am

If it ain't one thing, it's another.

The motor on my table saw is controlled by a gizmo that I think is called a "magnetic switch". It's set up to prevent the motor from restarting after a power interruption. I think it will also shut down if the motor draws too much current.

For some time now, the green "on" button has been getting harder and harder to push. Then yesterday, it got real easy to push (good) but the motor won't start any more (very bad). I'm guessing that something inside the switch physically broke.

I have yet to find a direct replacement for the switch. I haven't quite given up that effort, but if it fails I'll be looking for something that's just equivalent. This thing from Amazon looks like it might be close, but I'm mildly concerned about the current protection feature. The original switch has settings from 12.5 to 18 amps, but the range on the one from Amazon is 18-26 amps. I think this means the one from Amazon wouldn't be quite as sensitive to a mild overload condition, but I'm not sure about that. Of course the breaker that protects the branch circuit should trip if things really get out of hand.

For the record, the saw is an Inca 2200 "Professional" saw with a single-phase, 220V 3HP motor.

Anyway, does anyone have hints on an appropriate replacement? Or the importance of the current protection feature? Or anything I haven't thought of?

Thanks,

-- Russell Mac

saw_switch.jpg

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liveaboard
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Re: Replacement Table Saw Magnetic Switch

Post by liveaboard » Thu Jul 08, 2021 2:23 pm

That's a standard motor protection relay. You can see the adjustment screw on it to adjust for different motors.
Open it up, I bet you can fix it; otherwise, take it to an electrical supply shop and get a replacement.

rrnut-2
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Re: Replacement Table Saw Magnetic Switch

Post by rrnut-2 » Thu Jul 08, 2021 3:03 pm

Post a picture of what you have. It sounds like all it needs is to be reset. Usually that's done by pushing the red button in hard.

Jim B

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rmac
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Re: Replacement Table Saw Magnetic Switch

Post by rmac » Thu Jul 08, 2021 4:42 pm

Thanks, gentlemen.
liveaboard wrote:That's a standard motor protection relay. You can see the adjustment screw on it to adjust for different motors.Open it up, I bet you can fix it; otherwise, take it to an electrical supply shop and get a replacement.
Glad to hear it's a standard part 'cause I haven't been able to find anything even similar on the internet. The housing is a bunch of apparently snapped-together or glued-together plastic parts. So it's not clear how to get inside of it. I'm game to try, though ... worst case is I destroy it completely; best case is I find a way to fix it.
rrnut-2 wrote: Post a picture of what you have. It sounds like all it needs is to be reset. Usually that's done by pushing the red button in hard.
The picture I posted is the part I have. Pushing on the red button (hard, even) does nothing. I don't see any other reset buttons or anything.

-- Russell Mac

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Bill Shields
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Re: Replacement Table Saw Magnetic Switch

Post by Bill Shields » Thu Jul 08, 2021 5:07 pm

housing is one thing - what is in it another.

as mentioned -> it is a pretty much bog-standard motor starter relay.

you are probably going to have to settle for a different housing

try here for something close:

https://www.wolfautomation.com/enclosed ... KQEALw_wcB
Too many things going on to bother listing them.

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liveaboard
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Re: Replacement Table Saw Magnetic Switch

Post by liveaboard » Thu Jul 08, 2021 6:41 pm

It looks to me like there's a cavity under the label to the left of the green button.
There's likely a screw under there.

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Re: Replacement Table Saw Magnetic Switch

Post by Harold_V » Fri Jul 09, 2021 1:55 am

Might be a good idea to check eBay for Allen Bradley motor starters. I've purchased several (more than 10) from that source and have landed some outstanding deals, one being six of them for $15.00. They come in various capacities, and are adjustable through a respectable range. They also come in two styles, one with push buttons like yours, the other with a lever that is turned 90° for on and off. Both styles appear to function the same way. I have some of each and am well pleased with them. They can be used both single and three phase.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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rmac
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Re: Replacement Table Saw Magnetic Switch

Post by rmac » Fri Jul 09, 2021 10:36 am

liveaboard wrote:It looks to me like there's a cavity under the label to the left of the green button. There's likely a screw under there.
Good eye! I ripped off the label and there were actually three screws. Removing them didn't allow the housing to come apart, though. So I started prying and eventually got it apart without breaking anything.

The screws that I removed turned out to be adjustments of some kind, I'm guessing to set the current overload mechanism to trip at the correct point. With no way to return them to the correct positions, I gave up and ordered a new one from the place that Bill suggested.

For anybody in the same situation, searching for "motor starter" worked better for me than any of the other terms I tried.

One more time, thanks for all the help!

-- Russell Mac

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rmac
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Re: Replacement Table Saw Magnetic Switch

Post by rmac » Fri Jul 16, 2021 7:59 am

This is just another "close the loop" post. The new motor starter arrived yesterday. With a little help from YouTube I was able to get it wired up, and the saw is back in operation. The new starter is WAY bigger than the old one, though, so I still have to figure out a good place to mount it.

-- Russell Mac

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