Blew switch on my table saw... Questions...


Jon A

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Hi guys,

This is my first post (been lurking for a while). Love the site and hope you can help me...

I have a Steel City 3HP cabinet saw. It is running on 220 on a dedicated 30 amp circuit. I tripped the circuit today while using a 6" wobble dado blade. I shut off the switch (or at least I thought I did) and then flipped the circuit back on. The saw immediately turned on. I tried shutting it off by the paddle switch but it wouldn't stay off. I held it in the off position for a moment but then noticed a little smoke and a spark. I immediately unplugged the saw. The circuit had tripped again. I unscrewed the switch cover and there was a bit of smoke and the switch was warm.

The saw has worked fine for two years. Today was the first day using the 6" dado... I am wondering if that could be the cause. Should you only use an 8" dado/stacked dado blades on a 3HP saw? (I had bought the blade for an old contractor saw but never used it).

I am not sure where to go from here. Did I blow the switch? Any thought would be greatly appreciated.

Thanks in advance.

Jon A

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I agree ^^  I'd bet the culprit is the switch itself.  As long as it's toast, keep the saw unplugged and remove the housing around the switch and examine.  I had something like this happen on my jointer switch.  Turns out one of the plastic rockers that the switch rotated on had broke and allowed the contacts to go crooked creating intermittent contact and arching resulting in heat that melted more of the switch and started to smoke (luckily no fire B).)

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I browsed Steel City's site for product manuals... I found a few, but they were not informative... The few parts explosions I could find seem to show the use of push-activated switches on 240v saws -- a bad practice. Will need some more info...

 

Questions:

a. what is the model number?

b.is this a dual-voltage (120/240) or 240 only?

c.is the on/off switch push-activated or magnetic? if magnetic, have you played with the on-board CI?

d.prior to tripping the breaker in the box, did you smell anything like burnt insulation or notice the motor becoming excessively hot (sometimes the sawdust on the motor housing can get a bit singed)?

e.prior to tripping the breaker, did the saw sound normal?

f.According to their website, the saw has a 2-year warranty -- still under warranty?

 

Obviously, don't plug it in again until it's fixed. The switch is probably fried, but the trick is determining why... This could be a 5-minute fix with a loose ground or hot wire in the switch, a new $20 switch or, at-worse, the motor...

 

Do you have a volt meter? Do you have access to a volt-ohmmeter?

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I browsed Steel City's site for product manuals... I found a few, but they were not informative... The few parts explosions I could find seem to show the use of push-activated switches on 240v saws -- a bad practice. Will need some more info...

 

Questions:

a. what is the model number?

b.is this a dual-voltage (120/240) or 240 only?

c.is the on/off switch push-activated or magnetic? if magnetic, have you played with the on-board CI?

d.prior to tripping the breaker in the box, did you smell anything like burnt insulation or notice the motor becoming excessively hot (sometimes the sawdust on the motor housing can get a bit singed)?

e.prior to tripping the breaker, did the saw sound normal?

f.According to their website, the saw has a 2-year warranty -- still under warranty?

 

Obviously, don't plug it in again until it's fixed. The switch is probably fried, but the trick is determining why... This could be a 5-minute fix with a loose ground or hot wire in the switch, a new $20 switch or, at-worse, the motor...

 

Do you have a volt meter? Do you have access to a volt-ohmmeter?

a. 35905

b. 240 only

c. Magnetic I believe

d. Didn't smell anything until it tripped the circuit and I walked back to the saw. The cabinet was cleaned out earlier in the day but it wasn't bad to begin with (it is attached to a dust collector).

e. Yes

f. Purchased Feb. 25, 2012... I didn't get it out of the crate for at least 2 months so I am hoping they will honor the warranty. I will call them in the morning.

I did a little research online and it sounds like this saw has had this problem. http://forum.canadianwoodworking.com/showthread.php?24303-3-hp-switch-malfuction-and-quality-Steel-City-Service I don't think I was "short-cycling" the saw but I was sneaking up on the depth of cut with a box-joint jig so it is possible.

I do have a digital multimeter. I will probably just get a new switch from SC (assuming that is what their customer service dept recommends) and go from there. I certainly will not be turning on or plugging in the saw until this is fixed.

Thanks for the replies.

Jon A

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We've had to change a few of the switches in the machines in the work place ... They seem to slowly deform with heat and eventually they start to stick on or off causing them to trip the breaker.... We only have cooking equipment in there so it more of a nuisance than anything else but I'd hate to have it happen on a machine with a blade !!!!

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If it's a mag switch, you didn't smell anything and the saw sounded normal, then it's probably the switch - the c/i may be fused. That's a bit unusual (unless it's a cheap grade of switch) or you've been short cycling the saw...

 

BTW, most saws have cycles far longer than the one or two seconds mentioned in the other thread. You have to wait at least until you here the motor starter clutch engage (should be an audible click as the saw spins down) -- I think it's about seven seconds on my saw and has never been less than five seconds on any saw I've owned.

 

In any case, you should not be cycling the saw if you're sneaking-up on the cut -- unless you like purchasing switches and motors.

 

Even if the warranty lapses, a new mag switch will probably be less than $75 -- unless you want a commercial MS/CI, then it's closer to $300 -- and a lot bigger.

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I emailed Steel City this morning and received a very prompt response indicating that they would send me out a new switch, free of charge under my warranty.  All I had to do was send them a copy of my sales receipt.  Can't ask for anything more than that! :)

 

I was adjusting an F-clamp on a box-joint jig and probably shut off the saw for safety reasons (I am not a big fan of a loose metal clamp and my hands near a spinning blade!!)  I don't recall "short cycling" it but I could have.  Now that I am aware of the issue, I will certainly be more careful about turning it on and off. 

 

Thanks for the help!

 

-Jon A.

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==>I will certainly be more careful about turning it on and off. 

Same goes for other tools -- most user's manuals don't cover the issue at all --- and are generally pretty useless, but that's another pet-peeve altogether. I've only seen short-cycling discussed in one of my manuals (Oneida), but the situation really holds for all of the larger stationary tools. For example, the auto-start on my cyclone keeps the unit on for a minimum of 15 minutes after the last tool shut's down --- specifically so folks don't short-cycle the cyclone... Obviously, for safety reasons, you can't incorporate similar features in milling eqpt.

 

Anyway, SteelCity took care of you -- that's great and good to know... Just take your time when wiring the new switch.

 

One point: The better MagSwitches also incorporate an adjustable interrupter (essentially, a small adjustable circuit breaker that's supposed to trip before anything really bad happens)... If your's does (it'll be obvious when you take the switch apart to wire it), note the setting on the existing switch and verify that the new switch is set to the same load (probably somewhere between 14a and 18a).

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Did you blow the dust out of the switch?  I've had a number of switches on different things that acted funny until I blew them out with compressed air.  The switch on my Powermatic 62 has done this many times, but the original is still working after being blown out with air those many times. 

 

A friend has a stainless steel Shop Vac that had a red "rubber" "dustproof" cover over the switch.  It got so you couldn't cut it off.  If you pushed the "off" side of the switch, it would shut down as long as you held the off position down, but as soon as you lifted your finger, it would start again.  I cut the "dustproof" cover off of the switch, blew the dust out, and it is still working like it should.

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I talked to Steel City today (I wanted to personally thank them for standing behind their product).  Apparently they stopped using the switch I had on my saw almost 2 years ago.  They now use the same switch on both the 110v and 220v machines (just wired differently).  The new switch is being mailed today.  I am confident that it will solve the issue.  The saw really has been great for the money and it is nice to know that they have good customer service.  

 

Tom  - The switch was clean when I took it apart and had been pretty well sealed so I don't think there was any dust in there.

Funny you should mention the Shop Vac... I have the same issue with mine.  My work-around was to use it as a dedicated vac for my 14" bandsaw.  I have it plugged into a power strip.  When I turn on the switch, the vac and task light for the saw go on.  Now I might have to cut the red cover off and see if that fixes it.  Thanks!!

 

-Jon A.

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==>They now use the same switch on both the 110v and 220v machines (just wired differently)

If you remember my first post, that tallies with my search of their manuals...

 

I'd be real interested in what type of switch they are using these days...

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I expect the new switch should be a good fix. 

 

The trouble with a lot of stuff made in China these days, is that the part looks like a part that serves a function, but beyond that sometimes there is little hope.  A friend bought a mass airflow sensor for a Land Rover.  It looked like a mass airflow sensor, but it would not work at all.  I expect that was the problem with the switch.  It looked like such switches used to look, but functioning, or having any longevity had little hope.

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