Hi all,
As a spinoff of my recent 'Drake drum skimming' trailer restoration thread I'm currently (ouch) giving this 'electrolytic de-rusting' or 'cathodic cleaning' of the brake drums a go (thanks to Peter Parry for the heads up).
I wired a bit of coat hanger under one of the wheel studs, held in place by a wheel nut put on backwards. The two drums sat in the solution ok with the coat hanger connectors sticking out and touching.
For the anode I initially used a 1m length of 1/2" diameter metal bar I had kicking around laid in the box.
I hooked it up to my 12V / 4A bench PSU and instantly noticed a cloud of bubbles from the outside of the drums nearest the anode. It was drawing about 3A.
I then added another anode into the opposite side and joined the two with a short jump lead and whilst I saw bubble off the drums on that side it was reduced because the PSU was current limiting and the voltage had dropped to about 10V.
I then dug out a spare PC PSU (as per the suggestion in the link), cut all the 12V (Yellow) and similar number of earths (black) and the On wire (green) and earth and stripped and twisted them up in the right groups. Joined the Yellow to my anodes and the black to my drums and shorted the green to the black and away it went (11.8V on my DMMM).
However it seems that (for now anyway) it's mainly reacting with the outside of the drums nearest the anodes and I'm now thinking of creating two rings of iron, sat inside the actual drum and isolated from it with some suitable spacers (some garden hose segments or similar) to try to focus the reaction more on the actual area in question?
Am I on the right track or will it do all over in time in any case?
Cheers, T i m
p.s. And this isn't going to affect the non rusty metal is it? ie, I'm not going to erode anything off my bearing mount surfaces?