From: "Bob May" 
To: "atmlist" 
Reply-To: "Bob May" 


That mirror should be very doable if you keep the mirror and tool rotating
so as to insure that you don't put any astigmatism into the glass surface.
John Dobson has used larger pieces of glass that thick to make some of his
mirrors and he does a decent job of keeping the astigmatism out of the
surface.  He does have a problem getting a good parabolic surface tho on
many of his mirrors as he just doea a simple startest for focus quality
which can mean mirrors as poor a 1/2 wave. A 6 or 9 point mounting will
insure that the mirror will be perfectly supported.
Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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