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Re: ATM 12x12x0.8" astrositall blank
>I have a chance to buy an 12x12x0.8 inch astrositall blank.
>What's the largest size mirror I can make out of it,
>because of it's thickness?
12". :-)
Take astigmatism precautions at fine-grinding and polishing.
I have a small program that gives you the sagitta, weight of the glass
calotte removed
to make the mirror concave, its weight, remaining weight (sorry all is in
centimeters and kg) ...
Better view this in non-proportional font:
Diameter = 30.48 cm
Edge thickness = 2.032 cm
Weight of blank out of PYREX = 3.306 kg
Weight of blank out of SITAL = 3.736 kg
f/d f sagitta thickness PYREX SITAL
@ center Calotte Total Calotte Total
1.00 30.5 1.91 0.13 1.56 1.75 1.76 1.98
1.50 45.7 1.27 0.76 1.04 2.27 1.17 2.57
2.00 61.0 0.95 1.08 0.78 2.53 0.88 2.86
2.50 76.2 0.76 1.27 0.62 2.69 0.70 3.04
3.00 91.4 0.64 1.40 0.52 2.79 0.58 3.15
3.50 106.7 0.54 1.49 0.44 2.86 0.50 3.24
4.00 121.9 0.48 1.56 0.39 2.92 0.44 3.30
4.50 137.2 0.42 1.61 0.34 2.96 0.39 3.35
5.00 152.4 0.38 1.65 0.31 3.00 0.35 3.39
5.50 167.6 0.35 1.69 0.28 3.02 0.32 3.42
6.00 182.9 0.32 1.71 0.26 3.05 0.29 3.44
6.50 198.1 0.29 1.74 0.24 3.07 0.27 3.47
7.00 213.4 0.27 1.76 0.22 3.08 0.25 3.49
7.50 228.6 0.25 1.78 0.21 3.10 0.23 3.50
8.00 243.8 0.24 1.79 0.19 3.11 0.22 3.52