slippage revisited...

**fjpod** · 03-29-2015, 09:59 AM

An old topic, but, new materials, new ARs, new equipment and new methods... It might be a good idea to hash it out again (especially since I am having trouble...ha).

We've had trouble in the past in our finishing lab with hydrophobic coatings. We always managed to work it out by using better pads, biggest block possible, sharp blades (we have an Optronics 7e). I even hear stories from people with the "better" wet edgers having similar problems. We have lowered our feed rate, rotation speed. We have tested our clamp pressure and it is fine. Ordinary and non-AR lenses come out fine.

Lately, we seem to be having trouble on high minus 1.67-1.74 with hydrophobic coatings. Could be a stock or surfaced lens... Not much trouble with poly, strangely enough. We've tried roughing down to a larger size, then reblocking for finishing....not much help.
I see Gerber/Coburn has introduced an edger that uses a drill bit to "cut" into the lens from the periphery while it remains stationary, carving away the periphery of the lens before finishing on a wheel. Anyone have experience with this system?

Anybody got a magic pad? Or some other cure? Has lens material and coatings gotten ahead of edging technology?

edit: Let's get the issue of applying the hydrophobic coating after edging off the table, Chris.

**PRECISIONLAB** · 03-29-2015, 11:34 AM

Based on your description of the edging process, you have an experienced staff. Perhaps disclosing which AR may lend to further comments and solutions.

Although most AR's have great hydrophobic coatings some may not have the protective "edge coat" which helps to reduce slippage. My concern is the fact that lenses are being deblocked and reblocked. If your deblocking the "edge coat" is being removed hence on reblock the pad is trying to adhere to the super hydro coat. Instead of running to a larger size we essentially crib lens in edger using the 002 onboard 58mm round shape and adjust size if MBS is larger. By cutting a round shape first there is less torque and stress to simply cut as apposed to cutting to shape.

**Chris Ryser** · 03-29-2015, 02:33 PM

Originally Posted by fjpod

Anybody got a magic pad? Or some other cure? Has lens material and coatings gotten ahead of edging technology?

edit: Let's get the issue of applying the hydrophobic coating after edging off the table, Chris.

In 1985 I came out with the first AR stripper and advertised it the then current optical magazines that you could remove AR coatings in 5 to 10 seconds in your office. I received a letter from the then not largest optical corporation in Tampa that they were going to take me to court, because AR coatings would not de-laminate ever.

In 1986 we had the first hydrophobic coating ever made. Our super slippery coating could be applied by a simple dip of 1 to 2 second twice in 30 second intervals. This application would be done as the last step just before inserting the lenses into the frame.

So actually there was never any slippage in the edger ever, due to a slippery hydrophobic surface.

Whenever needed and the coating got tired with time and age as all of them do, or rubbed off it could and still can be renewed any time you want.

Two years later we came out with the same product with an added anti-fog and anti-stat property, which then became a standard product for us. We call this one "Super Hydrophobic" and I still believe that nobody else has yet offered such a hydrophobic product.

Zero slippage while cutting and working with the lenses, once applied they are easy to clean and some also sold under that name. They also cost only a few cents to apply, as one bottle can do up to 200 lenses and more.

**jcasowder** · 03-30-2015, 02:05 PM

Sounds totally crazy and old-school, but when I have coatings where the lens likes to slip, I apply a thin coat of hair spray and let it dry completely before blocking. Then, I use a lighter or heat gun to heat the blocking pad a little. Makes it stickier. Since I started doing that, I haven't had an issue with slippage. Interested in hearing what others are doing to fix it, though!

**Don Gilman** · 03-30-2015, 03:55 PM

Way back we used to bench block our lenses using lead in a mold to fit the edger chuck and painted on a product call hydrosol?? to allow the lead to adhere better. Then we used hair spray and it also worked. Forgot all about it until your thread. Probably a great idea. Sometimes the old ideas...like songs, are the best. Washes off with water.

**fjpod** · 03-31-2015, 01:43 AM

Thanks for those suggestions.

For the moment. .. my labman tried a second rikki pad on the concave side of the lens. Seems to have held. He did the other lens without and it slipped. (Dumb move, huh? )

**ml43** · 03-31-2015, 02:28 AM

What type of pads are you using?

also, if the 7e is anything like the 2g, lowering the feed rate means nothing if the feed motor/servo isn't calibrated correctly.

Read the manual to see if there is a servo/feed motor burning in sequence, sweep calibration, troubleshooting feed rate, etc...

also, if it's always slipping in the same direction, you may need to check the axis bias as well.

**Tallboy** · 03-31-2015, 03:03 PM

Use Dynamic Labs Grip Xtreme tape (nothing is better)
Use Dynamic Labs Pro Edge Green pads

Or use their combo pad/tape product.

I have switched to it in 2014 when I started having issues again and I called around to some wholesale labs to ask what they were using, and like magic all slippage is gone.

The slipping you are getting on Hi Index might be because of the extra water in the cycle compared to poly/trivex.

I only use the tape and/or pads on the front of lenses, never front and back necessary (for me at least, and I edge on an 9000sx so that may be different for you)

I'm pretty sure the grip xtreme tape won all kinds of awards when it came out, it is amazing stuff SO MUCH better than any other "rikki" type tape.

**Slim** · 03-31-2015, 03:53 PM

I use the 3m pads... No rikki pads anymore. Any AR jobs I use a pad on each side. ( but mine is driven on both side, not sure that OP's does this.) There is a right side and a wrong side to the pads too... I peel off paper while on roll and apply the block, then lift that off.

Back when I had a horizon 3 and high minus hi index, id hand edge the top and bottom off quite a bit if I felt like it might be an issue. takes the "leverage"away thats causing the slippage.

**EyeSore** · 03-31-2015, 04:42 PM

Originally Posted by jcasowder

Sounds totally crazy and old-school, but when I have coatings where the lens likes to slip, I apply a thin coat of hair spray and let it dry completely before blocking. Then, I use a lighter or heat gun to heat the blocking pad a little. Makes it stickier. Since I started doing that, I haven't had an issue with slippage. Interested in hearing what others are doing to fix it, though!

Hey, I was going to recommend this very thing .