My knickers are in a twist

[drk]

We are receiving PALs from our lab that are "twisted", usually outwards (temporally).

We feel this may be due to "slipping" when edging, and we think that most of these are AR coated jobs.

I believe I've heard people talking about this, here.

Is this remotely possible? Do you AR coat before edging (I'd guess yes)?

[CME4SPECS]

DRK, slippage usually causes them to twist up and down not inwards and outwards

[opty4062]

Could it be a blocker issue? Oh and thanks drk for the mental image of your knickers...

[ml43]

most labs will ar coat and hydrophobic/oleophobic coat before edging.

it is possible to edge first, then ar coat. but sometimes you get defects near the edge.


they probably have an edger that is out of calibration for axis, or they may have recently changed leap pads, or hydrophobic consumables

[Jubilee]

Problem with finish blocker? Is it with a particular lab?

I noticed one insurance lab was sending me lenses that were technically on axis in lensmeter, but when I looked at the markings they appeared about 10 degrees off. The lenses were a freeform design so I know they were stamped as part of processing. The third time I sent one back someone called and said the lenses weren't off, the PAL markings were but actual lens was fine. The corridor seemed to be inset appropriately, as one can eyeball without the correct equipment. Since they refused to remake them, I dispensed them. So far, so good : /

[Robert Martellaro]

Could it be a blocker issue? Oh and thanks drk for the mental image of your knickers...

I haven't cut a lens in thirty years, but it seems to me that if the lens was slipping, it would do so in a symmetrically, nasal up on the right, and temporal up on the left. If true, then it's probably equipment calibration or user error if the reference marks are temporal up or down on both. The lab manager should be notified asap.

[Golfnorth]

I haven't cut a lens in thirty years, but it seems to me that if the lens was slipping, it would do so in a symmetrically, nasal up on the right, and temporal up on the left. If true, then it's probably equipment calibration or user error if the reference marks are temporal up or down on both. The lab manager should be notified asap.

That is exactly how the lenses would turn out if it was a slippage issue on the edger.

Regards,
Golfnorth

[Hayde]

An old edger model with new AR coatings will do just that, DrK. (Yes, the AR is applied to the uncut.) There's a number of newer blocks or intermediate adhesives that are sold to help this, but in my experience it's hard to get consistent reports of their efficacy. Any individual lab just has to trial-and-error how to resolve the issue.

If it's a new problem with an old lab, my first guess goes to 'breaking in a new lab guy.' Then 'new lapse in CS inspection.' (Somebody's on vacation.) Then 'new AR.' Then 'aging edger.'

Either way, keep a log of the jobs exhibiting the symptom. Hopefully you're making them redo the lenses at no cost to you. But if they're not swift enough to fix it on their own, call your lab rep to rattle some sabers if you need to.

[sharpstick777]

We have modified our edgers to hold blocking pads on both sides of the lens, Precision Optical makes custom blocks just for this purpose. Its the only way we found that is 100%. sure we use more blocking pads though, but it loads cheaper than twisting a 1.74 Transitions VII S series lens.

[Jubilee]

It is good to note that if the lenses are being turned in the same direction, both nasal up or down, then the problem is the edger. Either way, you need to make the lab redo em :)

[Chris Ryser]

Any slippage is due to the hydrophobic top coating (whatever name you want to call it) which is a super slippery coating that fills the pores, microscopic mountains and valleys, so dirt can not penetrate into the valleys.

These coatings are part of the big profit to be made when using AR coating equipment. Time has shown that these coatings are being worn down by the eternal cleaning action of the consumers, cleaning their lenses a few or many times per day.

There are ways to get around the slipping action in the bevel edgers without any fancy super glue pads. Just order your lenses without the Hydrophobic coating and apply it in your own store in seconds, for a couple of cents a pair. there are many OptiBoarders that are doing it. Saving money, time and frustration.

You can even reapply the slick coating when it wears down, while your customer waits, for free, or a charge as you prefer. Think about it that it could save you money, time and frustration, by ordering lenses AR coated without the slick coat and apply it yourself, and investigate this matter a bit closer.

[drk]

Optiboard is awesome. Never go away, folks. The world needs you.

[Chris Ryser]

\

Optiboard is awesome. Never go away, folks. The world needs you.

Yes drk ........................without OptiBoard you would be back in the optical middle ages and would have to take and believe all the advice from the next slick talking optical sales rep whose only intent is to push some products to make his commission.

These days you ask a question and get a hundred different answers, because everyone develops his own theories and thinks that is the only right one.

[drk]

A small price to pay for organic information.