I am currently in the process of re-organizing my abrasives and polishing compounds, so when Marcus mentioned the tedium of polishing his silver casts, my mind juped to this.
I have used this method once for buffing up the handguard for the rondel dagger when it was already mounted, so today just as further proof of concept of a procedure for buffing small parts that are difficult or impossible to do on the buffer due to complex gometry (or safety).
This is what I started with – an old rotary toothbrush head that I have saved up for this purpose specifically, an extremely old and corroded mirror holder (probably chrome-coated brass or something like that), a piece of never polished brass with patina (a waste piece from machining) and hard, coarse polishing compound. A bit too hard, this is a high-speed compound, a paste would be better, but I could not find it. Not pictured here are paper towels that I have used to wipe the polishing compound off of the piece after work and the green scrubbing pad (see further).
The corrosion on the mirror holder was extremely hard and resistant, so I had to use a piece of scrubbing pad too – but I only used it on the left (thicker) half of the part in the following picture, not the right, thin part so some of the pitting from the corrosion is still visible there. A big improvement over the initial state nevertheless.
On the brass cylinder, I did not use anything else than the toothbrush and polishing compound
It is hard to take pictures of the results, but in the end, I found a way – I think you can see which side is the unbuffed part of the brass cylinder, and which the buffed part. The time it took me was about 5 minutes, but it would be mere seconds on the buffer. Nevertheless, the biggest obstacle to using this on a bigger scale is the battery capacity of the toothbrush, but it could be useful for getting into nooks and crannies on small thingies.
©Charly, all rights reserved, click for full size.
Out of curiosity, could you MAKE a paste by crushing some polishing compound and suspending it in something appropriate? Would mineral oil work?
Ooh, also, I bet you can alter the toothbrush to take different batteries. You can solder a cord to the ends to the battery casing and run the other ends to any battery setup you like -- as long as its output has about the right voltage and wattage. If you used cells comparable to the ones the toothbrush wants but connect a bunch of them in parallel, you would have a setup with much longer battery life!
@abbeycadabra yes, you can make a polishing paste, with various success. I did not perform too many experiments myself yet, but I did have moderate success with WD40 and jeweler’s rouge (Iron (III) Oxide (haematite) dust). You can read a bit about that in the series about rondel dagger. But I think it would be better if the medium used for the polishing compound were a bit thicker, like vaseline or dubbin or beeswax.
Batteries in this toothbrush are unfortunately not accessible, so modifying it is not possible -- the whole casing is sealed water-tightly in plastic and the battery is charged wirelessly.
I use an electric toothbrush for cleaning some fritzy things. One of the big cleaning companies (I forget which one) marketed a cleaning tool just like a toothbrush, but way more expensive. I don’t have a TV so I’m not sure if they’re still advertising them, but a cheap toothbrush is a good enough tool.