Drilling carbon brushes?

I'm rebuilding an antique generator from the 30's and the brushes are a tad short for my taste, so I'd like to replace them. I have access to replacement brushes of the right size but would have to drill two holes in each for the mounting screws that secure them to the holders. Can it be done in a drill press with a slow rpm and feed, or are they doomed to crumble?

I'd be tempted to just use a drill held in a pin vise and do it slowly by hand. Much less risky that way.

3006guns said:

I'm rebuilding an antique generator from the 30's and the brushes are a tad short for my taste, so I'd like to replace them. I have access to replacement brushes of the right size but would have to drill two holes in each for the mounting screws that secure them to the holders. Can it be done in a drill press with a slow rpm and feed, or are they doomed to crumble?

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If Helwig Carbon cannot supply a drop-in replacement, I'd modify the brush HOLDER to braided lead-wire & 'tamper' type that could use the closest brush they could supply.

Work in metal, leave the carbon to Helwig - it's their "Day Job", after all - and you've solved the problem for replacement brushes going forward as well the first set.

Otherwise - what Scott said. Push drill, bow drill, hand pin vise - much as-in drilling pearls & c. And buy an extra set, anyway.

Making a brush narrower, thinner, or shorter is dead-easy with ignorant 'flint' sandpaper.

Drilling and attaching leads is better left to those who earn their crust at it, every day, partly because they won't crack until days or weeks later when you are right in the middle of something time-critical.

Thanks for the replies and advice guys. I'll do it the easy way and contact Helwig!

drill, but dub off the cutting lips as you would for brass.

I've always wondered if conductive epoxy would serve to secure the woven wire leads.....

I have quite a few brushes from old 1930s generators, mostly ford, they aren't new but they are mostly usable with plenty of life left in them, what are the dimensions? What do they look like? Can you post a pic? I'll look in my stash and see if I have any for you.

CalG said:

drill, but dub off the cutting lips as you would for brass.

I've always wondered if conductive epoxy would serve to secure the woven wire leads.....

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Been covered. In-depth. On PM..

Many a hole has been drilled in EDM electrodes that are heavily carbon based.
Drills pretty easy.