Re: Variac brushes (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "david baehr" <dfb25@xxxxxxxxxxx>


 The brushes in this variac seemed to be a press fit, one I pushed out of 
its holder with just my finger nail , the other (it has two ) was a little 
harder and had to be broken out. I did pick up a couple of used brushes 
from a motor shop, and made a couple of attemps , tryin to make them snug, 
but not to snug in the holder, but each time they would crack. I'll pick up 
a couple more and give it another shot. $60 + is alot for a brush 
replacement, but, it may come to that. Thanks!! ,dave

>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: Variac brushes (fwd)
>Date: Sat, 29 Jan 2005 21:18:16 -0700
>
>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
>
>