Can you double wall this thing? mount the rods to an 1/8" plate or so and
then affix this thinner plate to the 1/2" structural plate? Or mount the
standoffs on strips of metal say 6 strips of 6 and affix the strip to the
back plate?
lg
no neat sig line
"James Lerch" wrote in message
...
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.

The wall that these 36 points will be mounted to is 1/2" thick sheet
steel, and the end results has to be a leak free semi-strong support
(there's no real weight being supported, just the occasional need to
change the tungsten filaments.)

My Current ideas a

#1 Drill 36 holes thru the back wall, insert 5/32" bolt with an
O-ring on the outside, and a nut on the inside. However this becomes
36 new points to search for vacuum leaks!

#2 Drill 36 holes, but only 1/4" deep into the backside of the 1/2"
thick back wall. This leads to three possible mounting methods

A) Big Hammer, and just "Nail" the threaded rod into the
under-sized hole, and hope it holds together (Yea, uh huh g)

B) Heat the hole and braze the threaded rod into place, but
this might cause un-wanted heat-shrinkage in the back wall...

C) Use an adhesive that won't out-gass to hold the threaded
rods in place. (Like some type of epoxy, but these might see somewhat
high heat loads, and I worry the epoxy will break down over time)

#3 Drill the 36 holes, 1/4" deep, and Blind Thread the holes (sounds
like I'll be breaking a BUNCH of taps!!)

Any other thoughts??








Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction, Testing, and
Coating site)