Sparking power tool

funkey_monkey

Was using a chop saw last night which is not used very often and it started sparking violently from the brushes.
The brushes were chipped. I put in brushes from another saw, but the same thing happened. Put the brushes back in the original tool they came from and they were fine.

There doesn't seem to be any play on the motor mountings so I can't see why this issue world occur.

I sprayed the motor with electrical contract cleaner, but no joy.

Attached it a photo of the mirror. Did it just need cleaned down or is there some else that may be wrong here?


Edit: will add photo of the commutator when I can get to a a machine which will allow it.

hesker

I had this once after I replaced carbon brushes in a drill. Found that there were small bits of carbon residue that got fused on to the brush housing. With the new brushes in place the residue was preventing full travel of one of the brushes. Result was sparking and intermittent operation.

I cleaned the residue out meticulously with a dremel and problem solved.

autumnalcore

If brushes were chipped sounds like commutator has an issue like burrs or copper dragging.if it's been run with arcing for a while you get heat related issues like delamination and warping. Inspect the commutator.

funkey_monkey

Photos attached now.

Looks like motor overheated and melted at the windings.
It is scrap now.
Can I get a replacement motor easily or do I need to buy a whole unit?

Irish Steve

Depends on the make, which we don't know. If it's a chinese machine, unlikely, a "good" brand like DeWalt or makita, or hitachi, maybe, depending on the age. If Lidl or Aldi, how long have you had it, they ususally give 3 year warranty on their tools.

funkey_monkey

SIP - beyond warranty age.

Irish Steve

There are some possibles for parts in the UK that I can see, not sure about locally, but mail order will probably be the only option for the next while anyway. There are sources though, so if the rest of the tool is OK, it may be worth putting the money in to it.