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Thread: Edging Polarized Lenses

  1. #1
    Master OptiBoarder Joann Raytar's Avatar
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    Confused Edging Polarized Lenses

    I am looking for hints and tips on edging polarized lenses. For the most part polarized plastic and poly come out nice, but there are those few jobs that, when you are done edging them, show noticable stress marks at pressure points along the frame. The bevel placement looks right and the lenses aren't too big. I have even nitpicked until I have gone too far and handedged a lens too small but there are still signs of stress.

    I could see it if these were wrap frames and the lens base curves were too flat or the lenses too thin but ... why would a frame with a 4 Base front have these problems?

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    opti-tipster harry a saake's Avatar
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    Question lenses

    Jo , are you sure your edger wheel is in good shape and also that you have enough cool water on the wheel, also where are the stress marks showing up on the lenses, top, bottom, corners?

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    Master OptiBoarder Texas Ranger's Avatar
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    Smilie

    Jo, haven't had any of those problems since we went to dry-cut machines 7 yrs. ago. now use the Optronics 6E, really awesome unit.

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    Master OptiBoarder Joann Raytar's Avatar
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    We're using a Horizon edger also. The marks are showing up at the upper and lower nasal corners and both upper and lower tempral corners. Sometimes stress marks show up right where the bridge is soldered onto the metal frames.

    I have maybe seen one poly come back with a stress crack in over a year and a half. That's what's bugging me. If there was heat kicking up during edging, I would think we would have a problem with all of our poly's as well.

    I wonder if it has to do with shape. Are there any reasons why a Horizon would cut shape slightly off? It isn't a patternless and it appears to be on axis. I remember having a hard time with a very angular Tura frame years ago. The frame had some sharp corners and the lens just didn't line up right and made the frame look out of shape. I solved that one by touching the lens up by hand.

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    Bad address email on file OptiBoard Gold Supporter Sean's Avatar
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    Jo,
    Could it be the lens? .......as in type of lens fabrication?.....there are two ...far as i know that are out there. One being the laminated film between two plastic wafers. Or the new tech way of suspending the film within the mold(casting the monomer around the film)? Which makes the film become an integral part of the blank.Also known as In-Mold lamination. Just a shot in the dark.....what 's your thought on this?

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    Jo:

    Is your butt joint closed (the part where the eyewire closes, not to be confused with other definitions) without stress. Remember a lens can be a few thousands of a millimeter smaller than the eyewire without slipping. Other thoughts, undersize lens with a silicone frame insert (this would also provide a seal at the lanimation points.

    Chip

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    Master OptiBoarder Joann Raytar's Avatar
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    Chip,

    That may be a possibility I forgot all about. I see the eyewire is closed but that doesn't mean that the joint is closing properly. It is hard to explain but I believe you know what I mean. Stress is on the screw causing the ends to bend in not on the inside joint.

    Thank you.

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    since 1964 Homer's Avatar
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    Jo, are you saying that it happens on all polarized lenses or just some? All could mean the lens manufacturer!

    However .... being a strong believer in patternless edgers and noticing that your's is not patternless ... that is where I would look.

    While the dry edging may be OK, It has never been my favorite edging system. Nontheless, since I am not having problems with a wet system and Al is not having problems with the dry unit then it must be something else.

    We live in the 21st Century with products that are much more sophisticated (and I think better, generally) than we have had in years past. We also need 21st century edging systems - by this I mean 3-axis tracing and edging. Just as you have mentioned, patterns are noteriously off shape, size and axis. I am so glad to no longer have to deal with this on a daily basis.

    While you can do a good job with what you have by closely inspecting and removing form the eyewires, burrs and excess solder ..... conforming the "basecurve" of the frame to the bevel your edger left you with or very careful, meticulously hand edging each lense for shape and bevel placement ................... this is last century's technology.

    My suggestion is get into the 21st century and get a new patternless edger - you won't believe how much you can enjoy going to work again!

    :cheers:

    Homer

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    Homer is right about the patternless edgers, they will go far to reduce all sorts of edger related problems. One thing I have noticed is that poly lenses tend to show stress more than resin lenses do. I have to make sure that all tension is off the lens at the point of closure. Perhaps suggesting frames that have more
    pliable eyewires could help too.

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