Re: ATM Glass Advice

["A.T.S." <drummer@austin.rr.com>]

Sounds like you bought from the same person I did.
Dan Cassaro. He's a GREAT guy. And has been doing ATM for about 20 years. He's
made many with this glass and I recomended it.
I've made and 8, 10, 12.5, and have a 16 and 2- 20" on the side waiting.
A 20" at 7/8, such as we have, is REALLY pushing the envelope.
I bought the other sizes because they were cheap and because I could practice
on them before working on a 20".
People have made bino's out of his 20" glass.
I've made an F/5.5 out of the 12.5". Probably will go no lower than 6.5 on the
20", just to be safe.

Just my opinion, but if a person is going to spend $1K + on a piece of glass,
he/she may as well cough up the remainder for a brandnew scope. Although it's
not made by you, and you can't take the personal pride in it, it is afterall a
thousand dollars of your cash.
Hey, if you are not concerned over the 1k, then go for the pyrex.


Peter wrote:

> Hi,
>
> I'd like to get some advice regarding purchasing glass for a 20" scope which
> I'm considering to build. I found a company on the Internet which sells
> cheap plate glass but it is only 7/8" thick.
>
> I'd like to know if it a bad idea to pursue making a 20" f4.5 out of 7/8"
> plate glass or should I not be so cheap and cough up the cash for thicker
> Pyrex? The Sagitta works out to approx. 0.278" leaving about 0.600" of glass
> thickness in the center of the mirror. The cost difference is huge.
>
> I've already made a few mirrors from scratch (12.5" f5 is the latest) so I
> do have some experience but I'm certainly not an expert.
>
> Thanks in advance for your input.
>
> Peter
>
> P.S. I'd appreciate receiving links to other Internet sources of cheap glass