"setting" the brushes on a DA?

**embolism** · 05-01-2012, 04:25 PM

I thought I read something about this on AG but can't find it now for the life of me.

It had to do with slowing breaking in the brushes on your DA before you went at it on speed 6 from the get go. Kinda makes sense. You don't take your brand new car and then floor it when you get off the lot... (well you're not supposed to). Maybe breaking in your polisher would help with some of the issues with DA's I've read about recently. Anyone know what I'm talking about or otherwise able to shed some light on this theory?

I recall that when I got my GG6 a couple years ago, I was apprehensive to use it with a compound at first so I put it on speed 4 and practiced with some black hole on my hood until I got comfortable with the action, how to turn on and turn off the machine, not raise the pad while still spinning, going around curves etc...

Maybe what I was inadvertantly doing was setting the brushes. My GG6 has worked great since I bought it and haven't had any issues yet (knock on wood).

Mike Phillips · 05-01-2012, 04:26 PM

Couldn't hurt but I've never done it...

Knock on car paint...

**BillE** · 05-02-2012, 07:37 AM

I too remember reading that. But for the life of me, I can't remember who or where it is.

The best I recall is that because the armature is no longer 'lathe smooth', meaning there are now little ridges, etc., this gives the brushes a chance to mate to those 'ridges'. If you dynamite the throttle right out the gate, you can get a lot of sparking and arcing 'till the brushes seat.

I guess you could think it as breaking new brake pads/shoes if the rotors/drums were not turned.

Bill

**tuscarora dave** · 05-02-2012, 07:53 AM

Sounds to me like someone overthinking the situation. As mentioned above, it certainly can't hurt but is it really necessary? No. I've rebuilt a LOT of electric motors in my time and before installing new brushes I use a tool that I fashioned (by gluing a piece of emery cloth to a No. 2 pencil eraser) to contour the new square brushes to the shape of the commutator to reduce the risk of electrical arcing. That somewhat would be considered a preventive measure against a problem that could possibly occur. How many times in your life have you bought a power tool and fired it up right out of the box? Have you ever experienced any problems? Maybe some have but I never have.

opie_7afe · 05-02-2012, 04:31 PM

the tools are tested before they are shipped out so therefore "bedding in" the brushes are not needed unless you replace them but all it takes is a few seconds anyways, just do it on lowest speed if you are that worried.

**Ron Atchison** · 05-02-2012, 05:43 PM

Well there is some truth to bedding in brushes, actually a lot of truth to it, but for a power tool not really. I use to race electric RC cars and would spend well over a hundred dollars on matched battery packs, 6 sub C batteries per pack times three packs just to race then another three for practicing and setting up the car. Thats 16.00 per C battery. Then there were the hand wound motors that would go from anywhere from 100.00 to 150.00 a piece and you thought detailing was an expensive hobby! Anyway the brushes had to be run in so that they would match the com and then the com would be recut to true it back up as they swell when they are broken in the armature was then rebalanced as well. This was all to make sure you had the most amount of power you could possibly have to last the three minute race. Then there is the whole cut brushes topic but really none of this even applies to hand tools.

**habeba86** · 05-05-2012, 04:15 PM

Originally Posted by rzatch

Well there is some truth to bedding in brushes, actually a lot of truth to it, but for a power tool not really. I use to race electric RC cars and would spend well over a hundred dollars on matched battery packs, 6 sub C batteries per pack times three packs just to race then another three for practicing and setting up the car. Thats 16.00 per C battery. Then there were the hand wound motors that would go from anywhere from 100.00 to 150.00 a piece and you thought detailing was an expensive hobby! Anyway the brushes had to be run in so that they would match the com and then the com would be recut to true it back up as they swell when they are broken in the armature was then rebalanced as well. This was all to make sure you had the most amount of power you could possibly have to last the three minute race. Then there is the whole cut brushes topic but really none of this even applies to hand tools.

Dunk the motor in a glass of water

**Ron Atchison** · 05-05-2012, 04:35 PM

Used to do that too, all that does is break in the brushes.. Mostly ran them in motor cleaner to get all the dirt out of them but yes that is another quick way to break them in, but you still need to true the com and balance the armature after break in of a new motor.