From: "Richard Schwartz" 
To: 
Reply-To: "Richard Schwartz" 


Since you mention my name, I must point out that people have been building
telescopes and instructing others how to do it successfully for a long
time. Numerous publications tell you that the ratio of diameter to
thickness for a mirror should be 6:1.   That means that the largest mirror
you can make with
3/4" glass is somewhat smaller than you were going to do: 4 1/2.

The best way to satisfy those old farts is to heed their advice.   It is
absolutely certain that if you do not try a large mirror that breaks their
rules, you will never have the experience of doing a large thin mirror;
that is exactly what they want!  So get busy: the first step should be to
gather all those old books and burn them!

I would not go larger than 11" with your glass.  Therefore, I beg you
to defy me and all the other old farts from the 19th century and go go go
beyond my abilities to 16" or larger.   Mel has done it and he can
advise
you.  Get back to me when you need to design a mirror cell, and I'll show
you how to eliminate the mirror clip.

. . . Richard


----- Original Message -----
From: "Russell Jocoy" 
To: ; 
Sent: Wednesday, February 26, 2003 4:06 AM Subject: Re: ATM Too big, too thin?


>
>
>
>
>
> >From: John Vede Dudgeon 
> >Reply-To: John Vede Dudgeon 
> >To: ATM{at}shore.net
> >Subject: Re: ATM Too big, too thin?
> >Date: Tue, 25 Feb 2003 20:54:57 -1000
> >
> >
> >Regarding big vs. thin constraints, what would you say about a 1/2"
> >thick, 10" f8 primary? I acquired a 1/2" plate glass kitchen table
> >broken in two, and started thinking about the thinnest flexed mirror
> >one could make at that size. FLEX says it would perform very well, but
> >I thought I'd ask the list about ease of generating a sphere in 1/2"
> >[hopefully] untempered glass.
> >
> >John
> >
> >
> >
> >
> ("atm{at}shore.net")
>
>
>      John, go for it.. If the 1/2" plate glass table top broke in half and

> cracked it is most likely not
> tempered glass. If it would have been tempered you would have already
> sweeped up all the
> tiny pieces and put them in the garbage.  I am now working on two mirrors
of
> 5/8" thick plate
> glass, one 9" and one 10". I don't plan on flexing these. 
Hey , you have
> the glass, go to Richard's
> website and see how to round a blank and start grinding. Richard can even
> slump the glass for you.
>                   RUSS JOCOY
> ("atm{at}shore.net")
>
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