Sparks Inside Dewalt Router


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Old 05-29-06, 11:56 AM
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Sparks Inside Dewalt Router

I've got a Dewalt DW621 2 hp, 10 amp plunge router that I picked up at a garage sale. When I got it, the guy said he thought it needed brushes or something. I ordered the brushes, but found that the ones they sent me didn't seem to have the right type of connector to plug in. Anyway, I fired it up and it seemed to be working as is, so I decided to try it. I've used a friend's bench router a few times, but never a plunge router.

I needed to widen a sink cutout on a laminate countertop by 1/4", so I bought a 1/2" by 1" flush trim bit, set up a guide, and started cutting. Inside the housing, I noticed a whole heck of a lot of sparking going on--a lot more than you see in like a power drill under normal operation. I kept stopping and checking it out and smelling it, as I didn't know if this was normal. I took it real slow, and eventually got a real nice cut done. There was never any visible smoke, and I didn't really get a strong 'electrical fire smell'--no more than I get from my power drills after medium to heavy use.

Is it normal for there to be a lot of sparks inside that thing?
 
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Old 05-29-06, 12:24 PM
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No, it sounds like you need new brushes.

the commutator may need dressing as well.
 
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Old 05-29-06, 12:34 PM
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I guess I'll have to call Dewalt and find out why the brushes they sent me don't match the connectors in the router.

Maybe they can tell me about this commutator thing too.

Thanks!
 
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Old 05-29-06, 12:48 PM
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The commutator is the part the brushes ride on. Made of copper bars with small strips of insulation between each one.

This gets worn and needs to be dressed occasionally. If it is not relatively straight from end to end, it will cause the brushes to not achieve full contact with the commutator and cause poor performance of the motor.

Sometimes material gets dragged from bar to bar which causes a short circuit and even worse performance.

If it is not too bad, the brushes will wear into the commutator shortly. It is one of those have to see it to judge it things. If you replace the brushes and still have a lot of sparking, it probably needs to be dressed.
 
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Old 05-29-06, 01:25 PM
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How do you dress it?

Thanks again!
 
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Old 05-29-06, 01:38 PM
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Originally Posted by Timinindy
How do you dress it?

Thanks again!
I prefer formal but some folks like casual/beach attire.

Sorry, my sideline is not as comedian (as you should be able to tell) so I have to tell my (poor) jokes to somebody.

If it is extremely worn, it gets tossed on a lathe but usually I just use a little tool from the supply house that has a stone on either end of it of differing grits to rub it back into reasonable shape. With a little ingenuity you can come up with a lot of ways to accopmplish this. The general idea is to end up with a reasonably straight line from end to end of the bars and you want the thing to be reasonably round. The brushes do float so perfection is not neccessary but better is better.You need to be sure that the insulator is also cut so it does not get drug across the copper bars and then insulating the bars from the brushes at that point.

BTW: this is part of a larger part of the motor and cannot be replaced independantly of the larger part without special tools and knowledge.(ancient Chinese secret) (that might actually be funny if you are old enough to recognize the refference)

Hey, is all the traffic gone from yesterday yet? I'm looking to come down next year and need a place close to stay. I could show you how to do this while I'm there.
 
 

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