Re: ATM Big scopes

[jgmoreau@lino.com (Jean-Guy Moreau)]

>-- [ From: Richard Schwartz * EMC.Ver #2.5.02 ] --
>
>>>>If you use unannealed glass, I wonder how much it increases the chances
>of cracking the glass while you heat it?  Just a wild and crazy thought.
>
>Not wild and crazy... expecially after I have been exposed to some of your
>OTHER thoughts.
>
>The annealing of the glass has nothing to do with it cracking under thermal
>stress.  In fact, one common brand of PYREX oven ware is actually made from
>PLATE glass that is tempered (i.e., it is cooled rapidly on the surface so
>that the surface is under compression).
>
>When you do your fuzing and slumping, follow the advice in Ric Rokosz' July
>1984 Sky & Tel article: heat slowly. For glass like yours, I suggest heating
>to 550 degrees C at a rate of 10 degrees per hour.  That means that after
>two hours of heating, you will still be able to reach into the furnace and
>handle it!   Since you will have big buck$ in this piece of glass, it pays
>to be conservative with it.
>
>You don't want to lose your tail for a piece of glass, and you don't want to
>lose your glass for a piece of tail! (paraphrased from Louisiana folk lore)

Why pay for thick glass if you fuse it, use 1/4", it is cheap, hey Richard !
You can then heat at 100 deg. per hour and save a lot of electricity.