Proper Finish/Pin/Safety Bevel Dimensions?

[icare]

I'm seeing a lot of different dimensions to back-side finish bevels lately. It seems that many finishers are willing to provide what amounts to almost no safety bevel at all and I'm wondering what dimensions are actually required in finishing. Does anyone have a link or guide to finish bevel requirements?

I'd also be curious to learn if most finishers are providing a front bevel as a routine practice.

Thanks for the help! :)

[TLG]

Don't know of any guide but I'll offer the opinion of someone that's done finishing for close to 30 years:
There is no standard that I'm aware of, but basically you want a very fine finish bevel. If you go very heavy you will be left with basically a white outline of your lens shape which is not visually pleasing. Too light and, of course, you run the risk of chipping the edge easier.
Glass lenses will always require front surface safety beveling as the edger wheel leaves the entire edge, both front and back, with small 'chips' that MUST be taken out. On plastic lenses I never do the front UNLESS it is a rimless, especially a nylor type (the lens will chip much easier during insertion/removal if not done).

Some labs get real lazy on this because, frankly, if you receive the lenses already mounted you may have a hard time telling whether it was safety beveled or not. On my nylor rimless I'm also inclined to add just slightly more pressure on the back side to reduce sharpness in case the lens gets shoved into the wearers face.

[braheem24]

I'd also be curious to learn if most finishers are providing a front bevel as a routine practice.

Thanks for the help! :)

Usually front safety bevel for 4 base and lower beveled lenses or any semi simless, drill mounting or glass lenses.

[CME4SPECS]

Only glass needs the front safety bevel. Plastic on any rimless, I do front and back.

[Jacqui]

I do all materials, shapes & sizes front and back.

[finefocus]

I'm seeing a lot of different dimensions to back-side finish bevels lately. It seems that many finishers are willing to provide what amounts to almost no safety bevel at all and I'm wondering what dimensions are actually required in finishing. Does anyone have a link or guide to finish bevel requirements?

I'd also be curious to learn if most finishers are providing a front bevel as a routine practice.

Thanks for the help! :)

Enough pin-bevel so the lens won't actually slice meat, and no more!

[Chris Ryser]

I do all materials, shapes & sizes front and back.

Not only you should do this..................but everybody else should.

It is one of the first rules to know and do when edging lenses of any material.