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Re: ATM About making a glass blank
Look for casting, melting ...
I don't think anyone has been sucessful at making their own blank but there is a lot of information about why it didn't work.
"Michael D. Crawford" <crawford@goingware.com> wrote:
I would find it hard to believe that you could save money on even a 20" blank
by casting it yourself. You need a kiln you can get very hot and keep hot for
quite some time, and cool down at a precisely controlled rate. The equipment
for that is likely expensive.
Where you might save money would be if you made a number of blanks. Once you
have all the equipment then casting a single blank should be cheap. So if you
needed, say, ten 20" blanks I could imagine saving some money. You could pay
for the equipment by selling some blanks, but then it might be less effort to
just convince your boss to give you a raise.
May I suggest you find a low-cost blank at a swap meet or through a club? The
Central Maine Astronomical Society sometimes has blanks for sale. I personally
lusted after a full-thickness pyrex blank they had, but wasn't able to buy it
at the time.
On the other hand, I heard (probably on this list) that the Mt. Wilson 60"
mirror was cast from wine bottles. I think bottle glass would work fine, but
you would want them all to be the same kind of glass, and not a mix of
different types because you wouldn't be able to get them to blend evenly when
melted, which could cause warping from thermal expansion and contraction.
Mike
--
Michael D. Crawford
GoingWare Inc. - Expert Software Development and Consulting
http://www.goingware.com/
crawford@goingware.com
Tilting at Windmills for a Better Tomorrow.
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