stoning a commutator

Status
Not open for further replies.
Joined
Oct 28, 2002
Messages
144
Location
michigan
Anyone have any experience doing this? I have a electric snowblower that I replaced the brushes a couple of years ago. I have only used this a handful of times, and the brushes are gone already. All I did last time was put in the brushes. the commutator is pretty blackened up but not really worn down. I see there are different grades of stones, any particular one I should use?
 
Is it legal in your state to stone them?
laugh.gif


I'd go easy and just try some fine steel wool or similar to see how they clean up.
 
Originally Posted by ZeeOSix
Is it legal in your state to stone them?
laugh.gif


I'd go easy and just try some fine steel wool or similar to see how they clean up.


I'm no electric motor expert but I wouldn't put shards of conductive material down in the guts of such things.

Maybe brown scotch brite?
 
Stones are used while the motor is rotating. If that's your case I would go for something fairly mild. You can also buy the rubber eraser stone to clean the comm and if it isn't threaded or valleyed you can use a seating stone and ablow out with air. may be too much effort for an electric snowblower. If the comm is in poor shape you can always turn it on a lathe and drag the slots.
 
Originally Posted by eljefino
Originally Posted by ZeeOSix
Is it legal in your state to stone them?
laugh.gif


I'd go easy and just try some fine steel wool or similar to see how they clean up.


I'm no electric motor expert but I wouldn't put shards of conductive material down in the guts of such things.

Maybe brown scotch brite?


Maybe some super fine sandpaper (1000+ grit) would be better.

Regardless, follow up with compressed air to ensure everything is clean.
 
Are all the bars uniform in appearance, If not then the armature is gone.

Use 400 grit silicon carbide paper, brighten them up a bit if you are worried. You really do not want to move any metal, The old time turn in a lathe is not terribly useful as modern motors run very high RPM. I used a collet lathe, nothing else was accurate enough. They tend to rough turn, knurl and heat treat the shaft, then center-less grind so the center holes in the end of the shaft are not always on center. You can polish by hand, anything more takes good tools. Almost all brushes come from China now, and the quality can vary very widely. You want to watch the brushes closely and replace when worn so you do not damage a very thin commutator by arcing. Be sure to clean to undercutting between the commutator bars.

Rod
 
Last edited:
Originally Posted by dirtymudder...
I have only used this a handful of times, and the brushes are gone already. All I did last time was put in the brushes. the commutator is pretty blackened up but not really worn down. I see there are different grades of stones, any particular one I should use?
Does the motor run at its normal speed? Are the commutator bars uniformly "blackened"? If not, use an ohmmeter to check for open or shorted coils. Out-of-roundness or vibration due to bearing issues can kill your brush life.

Clean up with fine emery cloth.
 
Last edited:
A local motor shop owner always said to use only garnet paper as the rosin in emery cloth causes problems for the brushes. One way to clean the commutator is to use a small smooth [censored] file. We changed the brushes in a chop saw that didn`t last. Poor quality off shore product.
 
Status
Not open for further replies.
Back
Top