Re: Variac brushes (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FIFTYGUY@xxxxxxx 

In a message dated 1/29/05 4:18:11 PM Eastern Standard Time, 
tesla@xxxxxxxxxx writes:
> > Do you know where to buy brushes for an Ol General Radio  variac, or ,
> > how too repair them ??

    Well, I had a Superior Electric variac that needed a repair of the 
brush assy. One of the surplus 240V/30A units had been trounced during 
shipping, and the brush and wiper were shattered.
    Since I have access to a bunch of carbon motor brushes, I took a spare 
and ground it down to the size of the original variac brush. I wasn't 
particularly concerned with the grade of the original or replacement. So 
far, so good.
    What I did discover was that the original brush had a metal foil 
somehow bonded to the sides that didn't contact the windings. These in turn 
were what were soldered to the brush holder to keep the brush in place.
    Since I didn't have any brushes with anything similar, I mounted the 
sized piece of carbon into the holder with a bed of solder I carefully 
melted with a torch. It seems to have set up quite nicely.
    FWIW, replacement brushes are available from the current manufacturers 
of variable transformers (Staco, Superior, and the folks who took over the 
Westinghouse(?) ones). Might be easily modified for your Variac.

-Phil LaBudde