[ATM] ATM: Dave's thin mirror

["The Alarm Co." <tac@i1.net>]

Dave's 3/8" mirror is undoubtedly a tour de force, and is generating much
new information.  But, upon reading that his goal is to make mirrors cheap
and easy to make enough to give to school kids, I have to inject the thought
that maybe this is TOO thin.  Plate glass 3/4" thick is easily obtainable at
low cost from any glass dealer.  Just order a round table top, say, 12" in
diameter. Not expensive, especially if you need several.   A mirror of these
dimensions is easily ground by well established methods.  No slumping
necessary, nothing exotic needed to polish and figure, unless you want to
make an f/3 cassegrain!  Plate glass 3/4" thick may be a special order from
your local commercial glass dealer, but it will still be a lot cheaper than
a "telescope mirror blank" from United or WilBel.  "when you're up to your
neck in alligators, it's hard to remember you were trying to drain the
swamp".  Keep a keen eye on your objective! (pun intended!)  Are you trying
to make a bunch of quick, easy, cheap scopes,  or are you trying to advance
the frontiers of thin mirrors?  Either way, I salute you...just don't expend
unnecessary effort!

 *  Best regards, Bob
*
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