Trivex grooved mount minimum edge thickness?

[k12311997]

Lab people,

What should the minimum edge thickness on a grooved Trivex plus power lens be? I got a pair from Davis that are 3.2 at thinest.

thanks

[DragonLensmanWV]

I go with about 2.0 to 2.2 minimum for groove.

[gunner05]

I was thinking 2.0 as well. I wouldn't whine with anything up to 2.5 but over that, come on.

[edKENdance]

Having never worked with Trivex this is of some interest. With plastic 2-2.2 seems to be the standard. You can edge thinner but risk chipping. You can groove thinner with poly as well but it will fold/flex too much. Which one of these 2 outcomes is more likely to occur with trivex?

[PRECISIONLAB]

Sounds like Davis used a finished stock lens. 2.0 edge thickness would be ideal if grinding/surfacing.

[k12311997]

sorry should have mentioned that it's a progressive. 1.8-2.2 is what I'm used to from other labs with poly, I haven't used trivex much but am moving in that direction.

[WFruit]

As long as there is physically space on the edge for the groove, that's the minimum thickness. Practically, I'd say no less than 1.5, with 1.8~2.0 being the most common.

[eyemanflying]

1.8mm et is the ideal thickness.

[DragonLensmanWV]

Some edgers make a wider groove than others, and some can make two widths of grooves. I use the wide groove if the frame has no nylon inserts on the top rim.

[RT]

The minimum thickness is really a function of the thickness of the mount, and not the material. As other people have mentioned, 2.0 to 2.2 is considered normal. However, materials like poly and Trivex can be reliably cheated a little thinner as there is no flaking like you might experience with materials like CR39. A thickness of 3.2 would be much thicker than required.