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sagitta volume calculation

Hello to all,
does anyone know of a source for calculating how much glass in volume is taken out from any given mirror blank when forming a sagitta =I am melting my own glass in preformed mould,s and wish to know if possible the weight of glass needed with some degree of accuracy.

many thank,s
Dan

heritage 130 reflector ,25x100 revelation binoculars on 3 pole mounts, 12 inch raiseable dob, 8 foot dome, twin hexadecagon 630mm binoscope, homemade binocular mirror mount, various binos,
Volume of a spherical cap = (pi/3)(s^2)(3R-s)

where s = sag, R = radius of curvature

Mike

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thank,s mike,
appreciate that=very quick !
was wondering if there,s a simpler method like a calculator which only requires an input of the diameter and the planned depth-thank,s

heritage 130 reflector ,25x100 revelation binoculars on 3 pole mounts, 12 inch raiseable dob, 8 foot dome, twin hexadecagon 630mm binoscope, homemade binocular mirror mount, various binos,
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Let r=D/2, then

V = (pi/6)(s)(3r^2+s^2)

Mike

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My maths aren't so good as your,s---did you suspect ?

I will see if I can use both calc figures to my benefit. thank,s Dan

heritage 130 reflector ,25x100 revelation binoculars on 3 pole mounts, 12 inch raiseable dob, 8 foot dome, twin hexadecagon 630mm binoscope, homemade binocular mirror mount, various binos,
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