Re: ATM 12.5" f/5 Double-Arched Mirror Blank.

["Galogaza" <elizabeta.galogaza@siol.net>]

Thanks Roger ,

After reading lot about problems with mirror supports
in telescopes or during manufacturing ( grinding ,polishing and figuring)
I developed great respect for stress.

What you are saying ("The flat annulus is about 2 cm wide.
 And yes, the blank rests just on  that. ") contradicts everything
 that I saw in print or on the list.

And yet you wrote  : "And so far I have seen no signs at all of any problem
during
grinding/polishing/figuring--or in the telescope itself."

I am working on a 11 mm,  mirror 8",  f / 3,  spherical back, intended for
flexing ala Adler. I did not know how to support properly the mirror due to
its
spherical back in order to avoid any chance to stress it while grinding and
polishing.

After your post I will look at the problem differently.
Perhaps one dogma less.

Regards
Vladimir.