How critical are carbon brush sizes?

[CelticRambler]

Looks like my belt sander's going to need new brushes urgently. The unhelpful instruction manual doesn't give any details as to model type or brush dimensions, but my calipers says what remains of the old ones is 8.7 x 5.3mm x a well-worn stub, with a 10mm plain disc at the other end. All I can find in that style on Amazon and Ali is presented as 8x5mm. Will the missing decimals cause problems?

Given that this is almost obsolete tech at his stage, how can there still be so many millions of different styles and types and (as far as I can see) not even any kind of code to describe what replacement to look for? I recently had to replace the brushes on my table saw, and 'twas a devilish job trying to track down a suitable replacement.

[JayZeus]

I'd be inclined to keep looking.

Can you put up a few pictures of the brushes and also the make and model of the belt sander, or a few really clear pictures of the whole belt sander from different angles to help me figure out what the hell it is, and what other makes/models are the same under a different brand? I've a bit of a thing for hunting down and repairing things like this, so it'll be a fun challenge tonight.

[CelticRambler]

Will put up pics of the brushes later; in the meantime, this is the Amazon listing for the one I bought a few years ago (still available):

https://www.amazon.fr/dp/B08DHJ7C4B?psc ... ct_details

I've only just bought forty new belts for it, so can't wait too long - there's are doors and windows and other woodwork expecting to be made beautiful and smooth this side of Christmas!

[kadman]

I have cut down, sanded , filed, ground all manner of brushes on both domestic appliances as well as workshop machines and appliances. And have done it on cheap old items all the way up to DeWalt expensive items.

I have got every single one of them running perfectly for more use and abuse. And we are talking .2 of a millimetre here
I laugh in the face of danger

[kadman]

Hey CR....I just realised it was your query.

Tell me kind sir...........since when did "fine tolerances " enter into your work ethic. I saw the thread on the hanging "jacks", but never noticed any fine tolerance at play there.

[JayZeus]

Brushes.jpg

Use 9 x 6mm nominal brushes, whatever length you reckon is most appropriate. You'll find them in 12, 15, 18 and 20mm lengths typically. Use 320+ grit wet and dry paper to very gently tune the fit of the brush if it's not in fact a little undersized. I expect the ones you have would be spec'd as 9x6 anyway.

[kadman]

Hey JZ if you kicked his left cheek with a pair of steel toe caps, and administered the same boot with the same force for an additional .2 mm on his right cheek ......he wouldn't know the difference anyway, but you would have achieved the same outcome.

Here endeth the lesson, each cheek would be equally sore

[CelticRambler]

... And we are talking .2 of a millimetre here
I laugh in the face of danger

Yeah ... but we're also talking about a 14-15% reduction in surface area at the point of contact, which is (as the statisticians say) a not insignificant difference.

[CelticRambler]

Use 9 x 6mm nominal brushes, whatever length you reckon is most appropriate. You'll find them in 12, 15, 18 and 20mm lengths typically. Use 320+ grit wet and dry paper to very gently tune the fit of the brush if it's not in fact a little undersized. I expect the ones you have would be spec'd as 9x6 anyway.

What about the size/shape of the connector at the top? Those ones have "wings"; any others that I'm seeing are a sliced-off circle with no dimensions given.

[JayZeus]

They'll either fit, or you can reshape them, or swap the ones from your original brushes. A dab of solder and a good hot iron is all you should need.

Can't offer any other suggestions anyway, as it's basically impossible to get spares under the brand of tool you have. I expect it'll be sold under lots of different colours and names but I haven't found it, yet.

[kadman]

Yeah ... but we're also talking about a 14-15% reduction in surface area at the point of contact, which is (as the statisticians say) a not insignificant difference.

You wont notice it.

[CelticRambler]

In view of the foregoing advice (many thanks, both of you) these images are probably now redundant ... but a promise is a promise

[kadman]

In view of the foregoing advice (many thanks, both of you) these images are probably now redundant ... but a promise is a promise

Just as i suspected .....the best part of that tool when its working is going to be the new brushes that you have managed to cobble together.

CR, ...we seriously need to talk, you appear to be putting more effort into your dancing than property and tool maintenance. This has to stop

[JayZeus]

[CelticRambler]

CR, ...we seriously need to talk, you appear to be putting more effort into your dancing than property and tool maintenance. This has to stop

All work and no play would make CR a dull boy - and very miserable man.

The last three weeks have been spent entirely on property, tool and vehicle maintenance, with feck-all to show for it (oh, and kittens ) and nothing done in the garden at all; so the prospect of a weekend dancing with my barefoot Bohemian is the only thing getting me up in the mornings.

[JayZeus]

Fnarr fnarr