In article ,
says...
Greetings ALl,

I'm building a vacuum chamber for coating larger telescope mirrors (up
to 24" in diameter) (Amateur adventure, not really for financial
gains!)

I'm currently perplexed on the best method to mount the 36 evaporative
heating elements supports on the back wall of the chamber.

Currently I have a plan on how to complete the mounts, but first I
must support the 36 x 1/2" long ceramic stand offs.

Given it's a vacuum chamber that is also going to operate at quite a high
temperature of around 676 deg C with a 10^-6 atmosphere vaccum (based on
30 deg C external ambient temperature) you'd be best off tapping the
holes in to the plate steel chamber. If you take your time tapping the
holes by hand you shouldn't break a single tap.

The other alternative that is more elegant is to have a ceramic ring and
combined standoffs made by a specialist ceramic caster. Such a ring can
be mounted on half a dozen bolts around its circumference. Again the use
of blind mounting holes is a very good idea.

Ian