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

# sagitta volume calculation

Started by
astrobeast1
, Mar 07 2013 06:14 AM

4 replies to this topic

### #1

Posted 07 March 2013 - 06:14 AM

### #2

Posted 07 March 2013 - 06:26 AM

Volume of a spherical cap = (pi/3)(s^2)(3R-s)

where s = sag, R = radius of curvature

Mike

where s = sag, R = radius of curvature

Mike

### #3

Posted 07 March 2013 - 06:37 AM

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

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

### #4

Posted 07 March 2013 - 06:47 AM

Let r=D/2, then

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

Mike

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

Mike

### #5

Posted 07 March 2013 - 06:56 AM

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

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