On Nov 16, 2017, whit3rd wrote
(in ):

On Thursday, November 16, 2017 at 4:39:48 PM UTC-8, Bob La Londe wrote:
"Ed Huntress" wrote in message

See if you can get a small piece of Macor, a machineable glass
ceramic.

Wow! The stuff sure is expensive.

Yeah; soapstone, slate, pyrophyllite, and other natural products are also
machinable, and cheap as rocks.

I'd go with glass, even if I had to visit the crafts store and buy a sixpack
of round
mirrors and desilver 'em in lye. Or take a diamond blade to a Tabasco bottle.

I bet whats usually used is glass-epoxy sheet, which one can get from
McMaster. If one makes a blank-headed bolt from A2 steel, hardens it,
polishes the top flat with diamond film on a sheet of glass, and assembles it
with glass-epoxy washers to a ordinary steel body, this ought to make a fine
tool setter thats very durable when touched by cutting tools.

The classic alternative is mica sheet instead of glass-epoxy. This is the
most stable material available. The washers are widely used for insulating
power transistors from heatsinks. Sheets are available from McMaster.
Muscovite type is probably what you want. Washers are available from
electronics supply houses like Newark.

Joe Gwinn