Cribbing to frame shape?

[lensmanmd]

Thanks for all of the input. Some excellent points. I would like to clarify that I am not referring to edging in the generator, but, rather cribbing or shaping the lens something close to the frame shape in the generator. A few mm larger perhaps. Let the edger do the fine detail work.

Understood. Elliptical cribbing is the best surface option for your needs. Milling edgers will then take the surfaced lenses and crib them to the rough shape prior to beveling. This combination is the most effective combination.

[jefe]

Understood. Elliptical cribbing is the best surface option for your needs. Milling edgers will then take the surfaced lenses and crib them to the rough shape prior to beveling. This combination is the most effective combination.

It seems as though cribbing during the surfacing process is tricky and won't provide much size reduction. If the milling edger cribs -- and it does very well and quickly -- why bother trying to remove material during surfacing?

[lensmanmd]

It seems as though cribbing during the surfacing process is tricky and won't provide much size reduction. If the milling edger cribs -- and it does very well and quickly -- why bother trying to remove material during surfacing?

Better surface quality.

[JGor]

Yep,better surface quality. Less overhang during surfacing means the lens is not 'flexing' as much. The amount of movement depends on the material but overall cribbing will give better surface quality. Others have also pointed out that less surface area means less drag so the chances of slippage especially with the coated lenses is reduced.