Glass?

[sopticals (Stephen)]

Hi all, is it possible to source glass of decent quality thicker than 19mm(3/4") float for mirror making anywhere in Oz/NZ? It seems that one is caught between a rock and a hard place with 19mm float being of a reasonable price,but too thin for a serious big mirror project (30"+),and the high prices elsewhere (China,USA) for 1.5"-2" thickness substrate. Any help appreciated.

[scopemankit (Chris)]

You could try and find someone with a large kiln to slump 2 thicknesses of 19mm together.

[sopticals (Stephen)]

Originally Posted by scopemankit

You could try and find someone with a large kiln to slump 2 thicknesses of 19mm together.

Hi Chris, thanks,I had thought of that option,but not sure if I would end up with an end product that would be free of strain etc. At this point in time I have ground out a number of mirrors in 19mm float. 18.5", 20.25", 22", 22.15", 25". The last three are polished out,each with a focal length of 117.5".The last two I am currently figuring.I have the 22.15" at around 1/2 wave PV at the moment (aiming for 1/4 wave on its first working), the 25" is more stubborn at worse than a two wave error. For a serious project I need more thickness,but at an affordable price,but yes, your suggestion is worthy of further investigation.

Anyone out there with further thoughts or suggestions? Your imput would be much appreciated.

[racecar (David)]

Have a look at my post here.

http://www.iceinspace.com.au/forum/s...415#post794415