Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics Engineering = Taking what you have and making what you need.
"Many a night I saw the Pleiads, rising thro' the mellow shade, Glitter like a swarm of fire-flies tangled in a silver braid." Tennyson: Locksley Hall
Quote:You'd probably have better luck making your own glass from scratch rather than trying to melt and recycle glass that may or may not be the exact, same formula. If it is, good. If it isn't, you produce an expensive paperweight that warps and bends with temperature variations. The glass should be of a uniform type throughout the structure of the blank. The only way to guarantee this is to make the glass, which you won't be able to do with your kiln. You need large crucibles and furnaces for much higher temperatures. You have to melt and stir the mix(es) in the right proportions, and even though you might know the ingredients there might well be proprietary steps that are still trade secrets. This would be something that has "Caution, May Cause Death" written all over it.
Quote:make some slumped meniscus mirror blanks, either from thin pyrex blanks
-DannyMy warehouseMy Channel
Quote:I think that's a very good idea! Slumping plate glass is not a difficult project, and the generated curve would be a huge time-saver.
Quote: BTW a while back I found some large candle holder glass at Bed Bath and Beyond. These are a bit larger than 8" in dia. and 3/4" thick in the middle, with a 1/2" high wall around the sides to hold the (large!) candle. I wondered if two of these could be melted to make a 9-10" mirror blank.
Quote:Quote: BTW a while back I found some large candle holder glass at Bed Bath and Beyond. These are a bit larger than 8" in dia. and 3/4" thick in the middle, with a 1/2" high wall around the sides to hold the (large!) candle. I wondered if two of these could be melted to make a 9-10" mirror blank.
Or maybe they could be re-annealed to higher usable specs?
Quote: Might be a business model there... since I don't know of anyone selling cellular blanks.
Quote:From what i've read on world kitchens site, the pyrex formula has not changed in 45 years. Interesting.
Quote:I had always assumed that Pyrex was borosilicate glass, and there was never any mention of the soda lime composition. There's got to be a reliable test to tell one from the other. Refractive Index? Abs/trans spectrum?
Living at a dark site, I make scope when I have the inclination. I also do woodworking, cycling and other outdoor activities