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
Mount it on a wooden dop with sealing wax then either clamp that or work
freehand with a decent handle. Heat to release. Might need a few brass
panel pins with their heads just lower than the surface of the part
round the edge to resist lateral forces, but it's gotta be easier than
carving a pocket and wax will clean off easier at a lower temperature
than superglue. I've lapped dozens of copper seal washers I annealed
for reuse that way last time I rebuilt a diesel.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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