From: "Kreig McBride" 
To: 
Reply-To: "Kreig McBride" 


I just received a call from a friend of mine.  He calls when he has glass
for me.   So i expect to be picking up some 16" square x 1" thick
glass this
weekend.  About 5 sheets.   The glass is out there if you look.

I send my glass of to another friend of mine who cuts it into circles for
students in his mirror making class.

Kreig


----- Original Message -----
From: "Jerry B. Hillman" 
To: 
Sent: Thursday, July 03, 2003 6:32 PM Subject: ATM secondary glass


>
> Hi all,
> I have a 20" square piece of 5/8" plate glass sitting here
waiting to be
cut
> into sections to start making the secondary for this 16.5" telescope.
> Although it cost me nothing since I rescued it from the dumpster about 7
> years ago, it would be expensive to replace.  Two of the corners have
> cracked diagonally about 1/2" in from the edge so I know the glass is not
> tempered. I also checked it with crossed polorizers for stress. No
problems
> there. I hope to be able to cut what I need for the secondary, etc. and
> still have enough glass left to pass along to ATM's for small mirrors. It
is
> thick enough for up to about a 6" mirror. Perhaps eight in the hands of a
> skilled ATM.
> My biggest question. How do I cut this glass.  I have cut window glass
> before with no problems, but it is only 1/8" thick.  Is the procedure the
> same for thick glass?  I will buy a new glass cutter, but I don't want to
> destroy this big piece of glass.
> My second question. I know I need three pieces for interference testing.
> How much do I need for the whole process?  Comments and help are
> appreciated. This is a new venture for me.
> Clear skies, Jerry
>
>

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