Sparking and smell from brushes (chop saw)

[Tyler Keniston]

I've got a motor/electrical questions for those inclined to such things.

I have a craftsman miter saw that one day (suddenly it seems) starting sparking significantly from the brushes, and puts out an awful smell. Additionally it seems to trip the breaker (a breaker that usually is just fine running that and other tools).

Now I don't have a great grasp of electricity, so this may be a weird detail, but I had just placed a permanent magnet on the conduit feeding into the outlet this was plugged into. Can a permanent magnet on a conduit cause some strange voltage issue, which perhaps damaged the saw?

The brushes seem to have ample life (at least they have plenty of material and the springs seems good, not sure if they can die in other ways?). The commutator was fairly brownish/black. I cleaned it a bit, which didn't seem to help, but I have yet to give it a real polishing and clean between each contact.

My plan is to do more trouble shooting with the commutator / armature. But what I'm really wondering is if
1) the magnet could have played any role, and
2) if the brushes could be shot even though they have plenty of material to them (and spring are good).
3) assuming 1 and 2 is no, and no, does it seem possible that the commutator could have malfunctioned so suddenly (it went from no smell, to significant smell with sparking and breaker tripping)

Thanks for any help,

Tyler

[Mike Henderson]

The magnet absolutely did not cause your problem.

If the motor smells (or smelled) really bad, it's probably burned and gone. Burned motor is a very distinctive smell. Once you smell it, you'll probably remember it.

My guess is that the motor is drawing a lot of amps and that's why you're getting sparking around the brushes.

Mike

[Chris Hachet]

The magnet absolutely did not cause your problem.

If the motor smells (or smelled) really bad, it's probably burned and gone. Burned motor is a very distinctive smell. Once you smell it, you'll probably remember it.

My guess is that the motor is drawing a lot of amps and that's why you're getting sparking around the brushes.

Mike


Agreed. Magnet is in no way the issue.

[Tyler Keniston]

Thanks. I figured that was pretty far fetched, it was just one variable that seemed to change. I'm going to investigate the armature more... and new miter saws...

[Chris Hachet]

Thanks. I figured that was pretty far fetched, it was just one variable that seemed to change. I'm going to investigate the armature more... and new miter saws...Thankfully if you are on a budget, used Miter saws seem to show up on Craigslist pretty regularly.