"Michael A. Terrell" wrote in message
...
Gunner wrote:

On Mon, 14 Jan 2008 02:40:36 -0500, "Michael A. Terrell"
wrote:

Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

No, I've not. Works well I take it?


I made $5-$10 every time I did it. The vacuum cleaner guy kept
asking to see my "Armature Lathe', so he couldn't tell the difference.


http://www.officedepot.com/a/products/930032/Paper-Pen-Pencil-Eraser/
is the erasers I used to use, but back then, they were only 25 cents.

I used a modified Exacto knife blade to undercut the mica between the
copper armature segments. Part of the point was ground down to let me
hold it at a better angle, without damaging the edges of the copper
segments.

Turning down armatures and overhauling DC motors is the one paying job I've
ever done on my lathe. It was a real specialty -- old high-speed Mitchell
16mm movie cameras. I did one for a guy as a favor, he told his
camera-collector friends, and pretty soon I was getting mail from around the
country asking me to do them.

--
Ed Huntress