General Enquiries And Questions

I have just fitted some new Carbon Brushes for my Bosch Classix 1200 machine. It has worked fine then stopped so I changed the brushes that were worn down and now the motor is whirring a little. I have checked and they are the right way around.

I used Home Spare Carbon Brushes.

Any advice would be great.

TBH I will only fit genuine carbons, I do know some people say that Qualtex carbons are OK but have not used the Homespares ones, there are some nasty, cheapo's out there that are likely to damage the commutator.

They were £20 so thought they would be ok.

The shop owner has suggested I bring the motor in. I'm hoping that he will see they aren't fit for purpose and do a refund or get me some that don't grind.

Not too fussed about price just want ones that work!!

It could well be that the motor comm is already damaged.

Sorry, what's the motor comm?

It does appear the click occurs when the edges of the carbon brush run against the grooves in the copper cylinder.

That's the commutator and I reckon it's duff and a new motor the only cure.

Bugger. Any good places to get one?

I have seen people sand them down. Would that work as the machine does operate just makes a whirring noise during operation. I have only let it run for a few seconds before stopping it.!!

fsdss wrote:just makes a whirring noise during operation.!

A moderate whirring noise is to be expected with new brushes anyway as they need a full wash cycle or two to fully 'bed in'. So in some respects it may be just that, however if the noise is accompanied by the brushes actually sparking (arcing)at the contact point with the commutator then likely as not the commutator is at fault. Evidence of that is often one or more 'segments' are discoloured and once that is is the case then no cure can be found except the need for a new motor.

The segments are all clean and there are no obvious sparks. I'm keeping my fingers crossed. I do think it may be they are bedding in, may be wishful thinking!

The motor did not make the noise before so that may indicate it to be the brushes.

If the brushes were put in the wrong way for a short time would this damage the comm? I don't think they were but I managed to convince myself they were!!

Thanks for the advice Martin!!!

fsdss wrote:If the brushes were put in the wrong way for a short time would this damage the comm?

In the short term (i.e running it for a few seconds) then no damage would result. Longer than that?...could be damaging!

fsdss wrote:I don't think they were but I managed to convince myself they were!!

Were either or both brushes fitted in the wrong way then by just turning the armature with your fingers, a loud (something's wrong here?) type noise would be plainly obvious to those blessed with moderate hearing ability. Almost likened to fingernails scratching a blackboard. New brushes fitted correctly and the sound more likened to your true love gently blowing in your ear........

I've taken the motor and brushes to the engineer where I got them. He's inspected them and thinks they are fitted fine but need bedding in.
I'm going to put it on spin to do this. I'll keep an eye out for sparks from the motor as I do but I think that may be the issue.

fsdss wrote:I'm going to put it on spin to do this.

Ideal running in tip: Set on a 'rinse & spin' cycle and reduce the spin speed controller (if fitted on your model) to maximum speed of 800rpm.

Martin

Many thanks again. You have been a great help

Martin,

The carbon brushes have bedded in following your instructions and the machine is working normally.

Thanks again!!

Sam