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Good morning, being new on this forum I am looking for enthusiasts in Italy with experience in the manufacture of an RC telescope. I plan to build a 400mm RC. Ho 3 normal glass slabs with almost 400mm width and 15mm thickness. To cut 3 disci doesn't seem a problem to me (water jet). It is possible with fusion to merge these three slabs into a 45mm thick slab? You can already give a curve by doing “slumping”.
Thanks in advance!
StefanHi Stefan, welcome among us
Melt the glass and give it a concave shape “quasi” spherical by mold softening is possible, I also had it done for a meniscus of 20 mm thick.
Unfortunately, following the merger, the accuracy of the shape will not be adequate for the optical needs of an astronomical mirror, so it will take a long and difficult job of regularizing the surface to the required tolerances, before proceeding with the parabolizzazione of the mirror.
Having available 45 mm thick, I think it is more “sustainable” ( it's faster ) dig glass according to classic methods, whereas in 400 mm diametro, the depth required for an RC, it is not yet at prohibitive levels, it will be a matter of digging “solo” an inch of glass, more or less…
Anyhow, realize the hyperbolic short focal primary, it represents only half of the work, then you need to make the hyperbolic secondary, certainly more complicated undertaking than the primary himself, whereby, if you do not already have good experience in the manufacture of mirrors, I feel strongly advised against such an approach. Better to start with a Newton, which allows good results and great satisfaction even in the first processing !
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