Damaged Brushes.

[spokeshave]

Quick question...

Removed the big Triton router from the table today for the first time in about 12 months for some hand held use. So while it was out decided a clean up was in order. Removed the top cover and blew out all the dust then decided to check out the brushes, Its done some fairly heavy duty work of late.

I found that both had some damage to the ends (see pics). Is this a common occurence with motor brushes or a sign of impending failure? And would it be good insurance to replace them anyway?

The thing hasn't missed a beat (no crunching sounds of bits flying about inside) and i would hate for the thing to pack it in. It's been far too good for that.

Thanks,

Steven.

[echnidna]

can you post another pic showing the surface of the brush that rubs against the commutator

[spokeshave]

Does this help?

[echnidna]

They seem to be seating ok but the pics not high enough quality to tell for sure.

Do they rattle when just the brush (not the spring section) is in the brush holder.

Did you have to pull them out or did they slide out with no effort.

If they are not real loose (nor tight) they would probably go around again but I'd put a new set in.

[DavidG]

File the sharp corners off the brushes.
Plenty of life left in them yet.

[spokeshave]

Sorry about the pics, that's the best my camera will do.

They dont rattle in the holders and they slid in and out easily.

[echnidna]

If they don't rattle use them

[spokeshave]

Thanks for the replies fellas. Will throw them in and see how they go.

I think i might still order a new set anyway.

Steven.

[echnidna]

I replace bearings when I replace brushes on any of my power tools.
The cost is affordable and ensures very long life.
My TR12 roiuter is on its 4th set of brushes and bearings.

[Rossluck]

They do need gently sanding flat. The hollow that the commutator has created is causing shallow edges that are chipping. Not a gigantic problem but I wouldn't put them back in like that.

[echnidna]

Don't sand them flat on the face that rubs against the com, that will create excessive arcing until they fit the com again

[chrisp]

I'd be having a very close look at the commutator. It seems like the brushes have somehow managed to catch on the commutator and snap the edges off. It is a little worrying that both brushes have been damaged in an almost identical manner.

Check the segments of the communicator - is there a segment that is sitting a little higher than the others? Check the insulation between the segments - maybe a bit of the insulation is missing between a couple of the segments? Is the commutator worn - is there a hollow/groove worn where the brushes sit?

It could be worthwhile placing the brushes back in and carefully turning the shaft by hand and seeing if there is any obvious problems with how the brushes sit. Try turning the shaft backward and forwards and check if there is excessive tilting of the brushes - the holders might be too loose.

A suggestion: Next time, when removing brushes, carefully note exactly which way they came out, and which side they are from.

• If there is a problem it is useful to know exactly which way they were sitting to help diagnose the problem.
• And if there is no problem, you can put them back exactly how they came out - saving having to re-seat them (and perhaps also saving a little extra wear).

[AlpineRaven]

Don't file them flat as they'll cause arcing, you need to file exact same curve shape as your machine, before you put the brushes back in best to inspect the copper plate where the brushes sits on to ensure its all flat and smooth - no sharp ends, I've came across to them caused by bits and pieces falling and jamming up the brushes causing damage.
Cheers
AP