equation to figure out maximum frame size

[rolandclaur]

If one knows the patient p.d. and the blank size available, is there an equation to determine the maximum frame size possible to cut out the lens without having to alter the p.d? In other words instead of determining minimum blank size for cut out, how would one figure out what the largest frame could picked out that would accomodate the patient p.d. and lens blank?

[lensgrinder]

You could re-arrange the MBS formula, but you still need an ED. Keep in mind that this formula is for an ED that is on the 180 line and does not take into consideration vertical decentration.

FPD = BS - ED + PD
FPD = Frame PD
BS = Blank Size
ED = Longest Radius time 2
PD = Pupillary Distance

[Rafael]

Hi,

use the attatched file as follow:

if you know the Blanc size.

Put you Data into the excel file, then you increase the frame size,
and look on the diameter results. you can increase till you are in you
Diameter you have.

Hope it can help you.