Finding thickness anywhere on a lens...

[Uncle Fester]

On behalf of ilan1204 do any of you know the formulas required to determine thickness anywhere on a lens?

As I told him in a pm the last time I did it was 33 years ago in school and I have forgotten how.:o

I do remember needing 2 or 3 points of thickness to start and then going from there. I don't think we ever had a frame involved however.
[edit- OK the smokes out of the room for now so I suppose you just need to add the "decentration in" to the formula to get the thickness assuming a minus lens.]

I'll be reading your responses until the room fills with too much smoke from my head.:)

Thanks

[lensgrinder]

You can use the sag formula(not approximation). For the diameter use the amount away from the OC. For example if you want to find the thickness at in the vertical and your B was 30 use 30 as your diameter. Keep in mind that if your raise is 4mm then your diameter is 22.