"Don Foreman" wrote in message
...
On Thu, 12 Mar 2009 18:34:35 GMT, "Ivan Vegvary"
wrote:

I volunteered to fix a bunch of older Vemco drafting machines (elbow type)
for the local high school. A frequent fault is that the graduated base
plate can no longer be clamped by the "Protractor Brake". Said brake is
simply a thin piece of aluminum with a shoulder that pinches (clamps) down
on the protractor. It is approximately the size of a nickel and about as
thick. I successfully filed 0.007 inches of one side, however, it is a
difficult task freehand and removes a lot of skin from the fingertips.
If it weren't aluminum, I would simply place it on my magnetic chuck.

One thought I had was to carve a recess into a block of wood and use that
as
a work stop. An advancement would be to drill a hole into said block of
wood and use either my vacuum pump or mighty-vac to hold the part down.
Could also make in impression in a chunk of clay, but SWMBO says it would
take at least 24 hours to fire in her huge kiln.

Other ideas appreciated.

Ivan Vegvary

Lapidaries grind and polish rocks freehand. They use dop wax.
http://www.gravescompany.com/adhesive.htm

friend of mine polishes facets on glass chunks (up to about 50lbs apiece) by
embedding them in a puddle of paraffin, using a vibrolap, then gently
heating them up to get the paraffin off.