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Thread: High minus flat lens causing temple splay.

  1. #1
    What's up? drk's Avatar
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    High minus flat lens causing temple splay.

    I have an undispensed sunglass job that's on a flat base (~+2.00) in a Wayfarer-style frame (was made for plano sunlenses).

    The front itself isn't too distorted by the lenses...it still has about 5 degrees of faceform, but the temples splay outwards.

    The posterior part of the lens does protrude past the eyewire, and it seems to me that the lens is keeping the eyewire from rolling around the back of the lens, if you know what I mean.

    Questions:
    1. Is it the edge thickness? Does that happen?
    2. Is there a type of bevel that would help this problem?
    3. (Hey, if there is a bevel solution, it's a mirror and backside coated PAL, quite expensive, can it simply be re-edged, or does it need to be totally remade?)



    Also question:
    Should I just chuck it for higher lens powers and start going ophthalmic? Are they better suited for high power lenses?

  2. #2
    Master OptiBoarder
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    It is the backside hide-a-bevel that is usually the issue, sometimes size as well. I would take it to the handstone and change the angle on the back of the bevel on the temporal edge until it fits better. With the mirror, it won't be noticeable from the front.

    Order FF POW compensated lenses to match frame base curves, then adjust the back bevels and size as need for a good fit.

  3. #3
    What's up? drk's Avatar
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    Thank you!

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    Some edgers have a "follow frame " feature that greatly improve this splaying but at the cost bevel protruding out the front. The rear of the bevel should have 5 degree slope. Most dry edgers will have a blade available for this.

  5. #5
    OptiBoardaholic
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    Everyone above is spot on. A hide a bevel leaves the edge thickness of a lens behind the bevel straight out at a 90 degreen angle and that excess thickness is most of the issue. That wall of lens edge is holding the frame front flat and not letting the frame front relax around the bevel.
    Push your lab to pull lens bases as close to the frame front curve as possible and not to pull lenses based solely on lens power alone. Then see if they have edgers with a 5 degree slope as Chris says. Or better yet see if they have edgers capable of incline edging. Incline edging is when the whole edger blade or tool is canted during the beveling process. This canting is a calculation the edger makes according to the lens curve information the edgers tracer took after roughing the shape and the and frame curve information the frame tracer took when tracing the frame for shape and size. The calculation is variable and the edger makes adjustments as it bevels the lens through out the beveling process. Think 3D, with incline edging the bevel of the lens is being edged is being placed as close to the path and angle of the frame as possible at this time.

  6. #6
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    In a counter intuitive way, often with poor cosmetics—You coukd move the bevel apex extremely forward: This will often help avoid the splay.

    barry

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    This is a very difficult problem for a lab that receives hundreds of different frames to know all the issues each frame will encounter. If a lab is lucky enough to supply all the frames they have to fabricate the problem becomes much easier. We would run a test order with every new frame we would receive right eye -6.00 left eye +6.00. We also made an impression of the bevel on the frame using silly putty to determine the angle and depth of the bevel and if it was necessary to do an incline bevel. I believe only MEI has that capability. You can set the BC limitations in your LMS system so if an order came in with an Rx that could not go into the frame or if the dispenser requested a special BC the order would not process.

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    Ghost in the OptiMachine Quince's Avatar
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    Obviously, striving for the best lens fit is ideal but as for what the optician can do, I am in the habit of showing the patient how the frame will 'stretch' once their RX is inserted. I hold the frame so that the temples and pointed up and slightly flatten the frame front to show them how the fit will change. This can help alleviate surprises at pick-up and assure a good final fit.
    Have I told you today how much I hate poly?

  9. #9
    Master OptiBoarder DanLiv's Avatar
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    Quote Originally Posted by Kwill212 View Post
    I would take it to the handstone and change the angle on the back of the bevel on the temporal edge until it fits better.
    All the special bevel edging advice is correct. But to save the lens you already have Kwill is right, grind away that thickness at the offending upper temporal corner until there's enough room to bend that chunky endpiece into submission.

  10. #10
    What's up? drk's Avatar
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    I really appreciate the expertise that is brought to bear, here.

    Glad, as a dispenser, that there are people in manufacturing that know how to solve problems--that we create for them, sometimes!

  11. #11
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    I also need help with this, more of a visual learner. Can someone please do a video demonstration of this with commentary on the hand stone?

  12. #12
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    If you alter the bevel by hand you will get the lens in the frame but it won’t be pretty. Let the people who have the equipment to the job correctly in the long run the dispenser wins and the customer has the best they can be manufactured.

  13. #13
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    Quote Originally Posted by Opticia_n View Post
    I also need help with this, more of a visual learner. Can someone please do a video demonstration of this with commentary on the hand stone?
    +1 That would be very helpful!

  14. #14
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    I have a Hot Fingers and have, on occasion, pushed the hinges in a little to eliminate the splay.

  15. #15
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    Quote Originally Posted by Lensman11 View Post
    If you alter the bevel by hand you will get the lens in the frame but it won’t be pretty. Let the people who have the equipment to the job correctly in the long run the dispenser wins and the customer has the best they can be manufactured.
    Depends on how good you are on the hand stone I guess. Maybe I'm missing something here. What kind of magic bevel is an MEI going to put on the back of the lens that could be done on the hand stone in this instance? The back bevel just needs to clear the frame to seat the lens.

  16. #16
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    The MEI can can control the height of the bevel as well as the angle of the hide a bevel and you can do that on a particular part of the lens just to clear the temple. You may also put a T BEVEL OR A V to match the shape of the groove on the lens. Sun glasses usually have the back the frame higher than the front. That is to prevent the Plano lens from causing an injury on impact. Some sunglasses have a square bevel for the same reason as well as not have to put a bevel on the Planos. The MEI can duplicate all those requirements.

  17. #17
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    Yes clearly an MEI is the bee' knees, best around, do just about anything edger. I think it's an incredible machine. It can certainly tackle difficult jobs faster and easier than just about any other way, and it can of course do different types of bevels that can't be done on a hand stone. But we are talking about a 2 Base lens in a wayfarer type sunglass here. It is a simple and quick job to adjust the angle on the back of the lens for a perfect fit with no ill side effect, and the end consumer isn't going to know or be able to tell if it was done by a $120,000 edger or a hand stone.

  18. #18
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    Some Wayfarers made for Plano lenses as was stated unfortunately require a special edge type. In particular the model that comes with Plano glass polarized lenses it was never meant to be Rx’d but it happens all the time.

  19. #19
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    Quote Originally Posted by Lensman11 View Post
    Some Wayfarers made for Plano lenses as was stated unfortunately require a special edge type. In particular the model that comes with Plano glass polarized lenses it was never meant to be Rx’d but it happens all the time.
    +1

    @Drk says to the patient that the frame will sucks next time and he/she change her/his mind.

  20. #20
    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    Quote Originally Posted by Kwill212 View Post
    Yes clearly an MEI is the bee' knees, best around, do just about anything edger. I think it's an incredible machine. It can certainly tackle difficult jobs faster and easier than just about any other way, and it can of course do different types of bevels that can't be done on a hand stone. But we are talking about a 2 Base lens in a wayfarer type sunglass here. It is a simple and quick job to adjust the angle on the back of the lens for a perfect fit with no ill side effect, and the end consumer isn't going to know or be able to tell if it was done by a $120,000 edger or a hand stone.
    It is, but like all advanced edgers, including the Santinelli, the operator needs to have advanced knowledge as well. A tool is only as good as the one that wields it.
    Now, the MEI does require programming, even the EZFit.
    That said, once the machine is programmed and the operator is trained, magic can happen.
    In my hands, a 2 base lens for said Wayfarer will fit perfectly. In the hands of a few of my trusted acolytes, I can sleep at night. Others being trained, not so much, yet.
    Not just the Wayfarers, but many of the new sun frame designs. I’ve always said that if manufacturing opticians designed frames, we wouldn’t be having these discussions.
    I bend light. That is what I do.

  21. #21
    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    Quote Originally Posted by Lensman11 View Post
    The MEI can can control the height of the bevel as well as the angle of the hide a bevel and you can do that on a particular part of the lens just to clear the temple. You may also put a T BEVEL OR A V to match the shape of the groove on the lens. Sun glasses usually have the back the frame higher than the front. That is to prevent the Plano lens from causing an injury on impact. Some sunglasses have a square bevel for the same reason as well as not have to put a bevel on the Planos. The MEI can duplicate all those requirements.
    +1
    I bend light. That is what I do.

  22. #22
    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    Quote Originally Posted by Kwill212 View Post
    Depends on how good you are on the hand stone I guess. Maybe I'm missing something here. What kind of magic bevel is an MEI going to put on the back of the lens that could be done on the hand stone in this instance? The back bevel just needs to clear the frame to seat the lens.
    MEI can be programmed to varying angled bevels, step bevels, inclined bevels, or a combination of the above. Hilco C2s are T-bevels with a step back. WileyX are V bevels with a step back. Some suns are Ts of varying widths, some with step backs, some without.

    Enable Z data on your tracers, and even the 7EX becomes better. Your Santinelli, Weco/Briot, mr Blue, etc become smarter. But their abilities are still reliant upon the operator.
    I bend light. That is what I do.

  23. #23
    What's up? drk's Avatar
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    I know this is a bit far afield, but why oh why can't some frame manufacturer make a line of sunframes that are designed with Rx lenses in mind.

    The collection needn't be humongous.

  24. #24
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    We would actually use modeling clay to make an impression of the frame groove. Then we measure it with a vernier and recreate everything. You can’t possibly do this with every frame so we chose only to fabricate sunglasses we sell there is never any issues under these circumstances. Once stored in your data base it works like any other order.

  25. #25
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
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    The central problem with most acetate frame bevel grooves is that the frame front is milled flat.
    Then frame wrap is introduced, effectively moving the frame’s rear bevel groove shoulder further “inside” than the corresponding front part.

    The solution would be to undercut the rear section when milling the frame front. But then this would be an “extra” process in acetate manufacture.

    For molded nylon fronts, there really is no excuse.

    B

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