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problem with the table saw motor. Please help!

Minder

Apr 24, 2015
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Has the capacitator anything to do with the power charge? Becasue a friend of mine told me that it could have some power surge at the end, when I am turning it off, and since there could be some dust in it - that's what causes the flash at the end.

Because the area I was working at was not well ventilated and as such dust particles (probably) got into the motor...
Generally there is no capacitor on a Universal motor, induction motors, yes.
 

Minder

Apr 24, 2015
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Have a look at the commutator, the mica insulation in between the segments may be worn level with the commutator, resulting in the brushes skipping over the mica and sparking. The mica should be just below the commutator surface, so the brushes only ride on the comm. An old sawblade ground to a point makes a good undercutting tool, taking a small amount of mica out of the way.
Mica insulation has not been used for decades, where undercutting was necessary, now it is a 'wearable' material that wears down with the copper.
 

CENTERMIN

Nov 12, 2022
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here are the pictures of today and I was able to snap the brush as I sandpapered it two days ago.
The black box is some kind of regulator as when the saw is over heated it's automatically turning the motor off. The I did not opne the motor housing case despite removing all the screws and pins on the scale. If you have any suggestion I'll be more than glad to follow your lead on that front.

But I am more convinced that it's the commutator as the sparking from the inside of teh motor was like crazy today. I mean it was like a holiday festival on steroids with lights and stuff. I just need to get inside. I appreciate any assistance to get me sorted out the flah lights situation at the end.

Thanks
 

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kellys_eye

Jun 25, 2010
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Those brushes are 'worn to nubs' and the cause of the sparking. New brushes will be nearly an inch long! As they wear down the spring pushing them onto the commutator looses its 'push' and the 'light touch' the brushes then have create massive sparking. You can even see the erosion of the carbon from the sparking!

I suggested new brushes right at the start. My opinion hasn't changed. Just hope the excessive sparking hasn't damaged the commutator - probably nothing some light abrasive couldn't fix though.
 

CENTERMIN

Nov 12, 2022
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Those brushes are 'worn to nubs' and the cause of the sparking. New brushes will be nearly an inch long! As they wear down the spring pushing them onto the commutator looses its 'push' and the 'light touch' the brushes then have create massive sparking. You can even see the erosion of the carbon from the sparking!

I suggested new brushes right at the start. My opinion hasn't changed. Just hope the excessive sparking hasn't damaged the commutator - probably nothing some light abrasive couldn't fix though.
I'll take care of it this weekend. I am going have to work but this saturday-sunday I will buy a set of new ones and change them.
But the flash at the end is my main concern. What do you think about it?
 

roughshawd

Jul 13, 2020
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really great ideas..!
Pull the cover off the end thats sparking and you will see there are plenty of little parts to lose in the dirt near your feet. All of them are important and necessary for the thing to work right.
I just thought I might throw in, it will|is working other than the spark right? So sometimes its a better idea to just use it carefully until it fails, or you have the time to really fix it.
A motor doesn't usually spark out unless there is a power issue like a loose wire on a brush or an insulation problem on one of the coils. I have an old drill that arcs to beat the band when you fire it up, but that is because I haven't polished the commutator, and cleaned then insulated the wiring. That looks like you might have a natural buildup of electricity in your wood shed and the static charge is happening when you create a tornado by spinning the blade on the motor, the resulting hurricane causes a small lightning bolt to discharge when the switch is thrown. Put the saw on a rubber mat on the floor, and hand a couple of those vinyl door strips across the dry storage area between the saw and you and see if it doesn't stop.
2. a bad switch can cause a power problem that causes arcing also. Imagine a power switch that turns on and off 25 times before it actually turns off....
3. never put your fingers near the saw blade... or the electrical connections or motor...
4. Always wear goggles
5. Gloves are not always a good idea
6. Spray the motor and commutator with Contact cleaner, then let it dry.
 

kellys_eye

Jun 25, 2010
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Note to OP - don't take any notice of the above.......
But the flash at the end is my main concern. What do you think about it?
Not a lot. New brushes should sort everything (assuming commutator is ok/clean).
 

CENTERMIN

Nov 12, 2022
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really great ideas..!
Pull the cover off the end thats sparking and you will see there are plenty of little parts to lose in the dirt near your feet. All of them are important and necessary for the thing to work right.
I just thought I might throw in, it will|is working other than the spark right? So sometimes its a better idea to just use it carefully until it fails, or you have the time to really fix it.
A motor doesn't usually spark out unless there is a power issue like a loose wire on a brush or an insulation problem on one of the coils. I have an old drill that arcs to beat the band when you fire it up, but that is because I haven't polished the commutator, and cleaned then insulated the wiring. That looks like you might have a natural buildup of electricity in your wood shed and the static charge is happening when you create a tornado by spinning the blade on the motor, the resulting hurricane causes a small lightning bolt to discharge when the switch is thrown. Put the saw on a rubber mat on the floor, and hand a couple of those vinyl door strips across the dry storage area between the saw and you and see if it doesn't stop.
2. a bad switch can cause a power problem that causes arcing also. Imagine a power switch that turns on and off 25 times before it actually turns off....
3. never put your fingers near the saw blade... or the electrical connections or motor...
4. Always wear goggles
5. Gloves are not always a good idea
6. Spray the motor and commutator with Contact cleaner, then let it dry.
ok.. so contact cleaner and change of venue to a more ventilated area.. I got you. But, what about the flashes. You see, the flashes are my main concern. How do I get rid of these.. ? Thanks
 

Minder

Apr 24, 2015
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If you have an arc (blue-ish) , or flashes that follows a circular path around the com as it rotates, you most likely have a short in the armature. If this is the case, and if if in doubt, remove the armature and take to a rewind shop and ask for a growler test to be done.
BTW, the evidence from the brush edges indicate severe flash due to high current arcing. Sort of confirming the armature problem.
 
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Minder

Apr 24, 2015
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If it has had a great deal of use, Another thing to check, while you have it down is the bearings.
 

CENTERMIN

Nov 12, 2022
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Note to OP - don't take any notice of the above.......

Not a lot. New brushes should sort everything (assuming commutator is ok/clean).
one question though when i was browsing for brushes, what kind of brush should i use? Or just about any brush will suffice?
 

CENTERMIN

Nov 12, 2022
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If it has had a great deal of use, Another thing to check, while you have it down is the bearings.
I will look through everything and I WILL be back with more videos and photos. This is not over until those damn flashes go away.
 

Minder

Apr 24, 2015
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one question though when i was browsing for brushes, what kind of brush should i use? Or just about any brush will suffice?
You should use the same composition and of course, length/size, IOW, if possible obtain manuf. replacements. !
Different brushes have different copper/carbon content, depending on the application.
 

CENTERMIN

Nov 12, 2022
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You should use the same composition and of course, length/size, IOW, if possible obtain manuf. replacements. !
Different brushes have different copper/carbon content, depending on the application.
how do i know the composition, length or size of this thing?? I mean it's been burned and for the composition.. well.. should I taste it to figure it out?
 

Minder

Apr 24, 2015
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If you do not want to go the OEM parts route for a source, then take them to a local motor rewind shop etc and see if they can make an educated guess on a replacement.
Obtaining them off the web etc, i.e. just going by existing size will be a crap shoot.
Technically if the com has ridges, you should also obtain a com stone in order to bed them in.
 

Bluejets

Oct 5, 2014
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Seen enough of these to know you've cooked it.
Get a new one, any amount of cleaning etc. went out the window ages ago.
 

CENTERMIN

Nov 12, 2022
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Seen enough of these to know you've cooked it.
Get a new one, any amount of cleaning etc. went out the window ages ago.
again with the euphemismus.. what do you mean by "cooked" it? The brush, the commutator or what do you mean? Thanks
 
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