ATM 38"glass/cutting/slumping/etc

[Kreig McBride <kmcbride@memes.com>]

Regarding my 38" x 3/4" glass "Blank". Thanks to those who responded with 
ideas and comments. My intent is to stimulate conversation about large 
thin mirrors. Larger and thinner than what might have been done before 
requiring new techniques and technologies, or further refining what 
others have already accomplished. I eventually will need to decide if 38" 
is realy too large (foolish) and a smaller mirror is more practical 
(successfull).
   A project like this requires a lot of interesting and exciting 
problems to solve, involves many different people and recources (good). 
The first problem I have encountered is figuring out how to remove the 
glass from my van (bad).
   I am inclined to try the diamond bit in a router on a circle cutting 
jig to cut a circle. The proposal to spin the glass and use a stationary 
cutter was appealing at first untill I realized that spinning a door 
sized chunk of glass might get to be a bit too interesting.
   Several of you have hinted about a need for 10", 12", 15" blanks. I 
appreciate your needs and requests. Right now just the effort of dealing 
with the 38" blank will keep me busy. (We do give away a few blanks at 
the Telescope/Optics Workshop, but that is another story (free 
advertiseing here)).
   Still interested in comments on very thin/large mirrors, glass 
cutting(circles/thick glass), and flotation cells(flotation, RV cement, 
bubble pack, etc,) and slumping/fusing.

Kreig McBride
Bellingham, Wa
Telescope/Optics Workshop
March 19,20,21  1999



R. Dugan wrote:
> 
> > I picked up my 38"x 66" glass sheet today................
> 
> Kreig,
>         I am new to this group but I saw you post and thought I would throw my 2
> cents in. In Mass there is a person who builds unobstructed reflecting
> telescope systems. (DGM Optics) In conversation with him he stated that he
> grinds the whole mirror system out of one solid blank. He then gets the
> individual mirrors he needs out of the one piece. He CNC machines the
> mirrors out of the main piece of glass. It would seem to me that this would
> be the most accurate method of cutting your blank. The only problem may be
> the sheer size of the blank you have.
> 
> Let me know if this has helped.
> 
> Bob
> 
> Bob Dugan
> bob@garden.net