[TheForge] Motor brushes

[Bruce Freeman]

I've seen some brushes that contain no wire.  If it
can make friction contact with the armiture, it can
make friction contact with line voltage.  Usually
there's a spring to make the actual contact, IIRC.

However, I just pulled a brush out of a throwaway
angle grinder and found that it is an assembly:  A
carbon brush with a wire soldered to a thin metal
disk, the wire surrounded by a spring.  Interestingly,
the wire comes out of a hole in the carbon brush.  How
is it attached?  No evidence of solder.

So, I asked myself how I would construct this.  I
don't know if solder would stick to a carbon brush,
and I doubt it.  However, drill a hole maybe 1/4 in
deep, insert wire, and  pack hole with lead  wool and
I bet you'd have a working brush.  Might want to dip
the lead wool in vinegar first to give it a clean
surface.  Maybe some other packing would work as well.
 In a pinch, I might try very fine steel wool, also
cleaned first.  I can't say these ideas would work, as
I've never tried them.

Bruce
NJ
--- Dan Brewer <danqualman at gmail.com> wrote:

> The wire is part of the brush. 
> 
> You will need to find new brushes.
> 
> Dan in Auburn
> 
> -----Original Message-----
> From: theforge-bounces at mailman.qth.net
> [mailto:theforge-bounces at mailman.qth.net] On Behalf
> Of Lynn and Susan Lang
> Sent: Sunday, April 01, 2007 2:53 PM
> To: theforge at mailman.qth.net
> Subject: [TheForge] Motor brushes
> 
> Hello
> How does the brush manufacturer connect the fine
> copper wire to the
> carbon brush? 
> I have repaired the forge blower motor brush,
> soldering the wire back
> onto the brush, do not know if a good fix or not. Am
> in pursuit of a new
> pair of brushes.
> 
> It appears that maybe copper flakes are embedded
> into the end of the
> brush, or it could just be copper from the wire that
> I pulled out... 
> 
> Or is a different repair method better? 
> 
> Thank you
> lynn
> 
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