buddy of mine edging Poly having issues

[Aarlan]

Any additional input would help.

A competitor down the way called me about having problems with poly lighten up a/r lenses. He edged a few jobs, and about 3 days later upon dispense, there were stress cracks in the lenses.

I ascertained and recommended the following:

• He's using a dry cut edger...I told him to check blade sharpness/replace with new cutters
• The frames are zyl (square) and he cold snaps so he contends they are not too big...I told him his tracer may be older and may not trace the square shape properly, thus putting additional pressure at certain points on the lenses...sort of like when the patterns we made were a hair off.
• I also recommended the Resolution poly lens...I was told by many on this board that this was a higher quality poly lens that would reduce/eliminate stress cracks...Are there any other brand names you would suggest?
• I also suggested he try trivex, but the power was a -5.00, and the trivex may not be thin enough for the price.

Any other suggestions? I know I should be dancing around with joy that my competition is having problems, but I am a sucker for helping folks out and teaching folks new stuff. I guess I'm a better optician than businessman.

AA

[High_Abbe]

Tell him to retouch the lens instead of tightening the screw so tight that the head pops off!!!!

[For-Life]

1. Double pad
2. Light settings
3. ALWAYS use a small chuck

[Aarlan]

Tell him to retouch the lens instead of tightening the screw so tight that the head pops off!!!!

Zyl Frame...see post

AA

[Aarlan]

3. ALWAYS use a small chuck

Wouldn't a larger block with the optimum curve be better to spread the torque to a larger portion of the lens? We used to have a problem in my other life with small blocks with poly A/R in small B frames.

AA

[High_Abbe]

Zyl Frame...see post

AA

My mistake.

[Aarlan]

Although he contends that since he cold snaps it in, it couldn't possibly be too big, but I'm not sure I believe that...Do you think that would cause undo stress?

AA

[Jubilee]

The block should have the same curve at the front of the lense, if at all possible. The idea is to have even pressure, and maximum contact while edging.

I wonder if he might be using a bit too much pressure popping those lenses in. Especially if the lenses aren't "quite" perfect in shape.

Cassandra

[High_Abbe]

Now that I think about it, it must have something to do with his edger. I mean I have never had anything like that happen with poly so quickly. It's usually a drill mount after about a year, or someone is using acetone to clean the lenses........

[Leo Hadley Jr]

If your friend is using metal blocks on a horizon, tell him to use the black flatter blocks and turn down the chuck pressure to about 50psi. This will cure the problem.

[For-Life]

Wouldn't a larger block with the optimum curve be better to spread the torque to a larger portion of the lens? We used to have a problem in my other life with small blocks with poly A/R in small B frames.

AA

When you have a large block you have the large block on the one side against the small clamp on the other. So the one side is pushing against the other and the other has nothing to push against. Then you get the lens bending over the chuck. With a small chuck you have equal pressure on both sides.

This worked for me

[fjpod]

I'd stress the blade. There is a tendency to want to stretch the life. You can get away with an old blade on CR39 almost forever. But when it starts to get a little dull (around 300 cuts) you are gonna start having poly and A/R problems.

[Rich R]

Cleaning solution may be the cause ?

[spartus]

Lighten Up lenses are pretty low quality. Resolution with AR is a good first step, cost- and quality-wise, but Crizal or Alize uncuts would be better still.

Second, does he have to cold-snap? Just using a little heat with a trusty Hilco frame warmer is significantly easier on the thumbs.

[Excel-Lentes]

Hi Aarlen,

I would guess it is the blade. I use the old Horizon II and I really stretch the life of the blades for CR-39 but I learned never to skimp with Poly and High Index. If I have one poly to edge I will change the blade and then change it again for CR-39.

I haven't seen stress cracks on lenses in zyl frames. Is this person putting an appropriate safety bevel on the lenses?? Where are the cracks located? Nasally, Temporally???

[SpecialT]

I would say that the chuck pressure or cleaning solution are the most likely culprits, but sometimes (particularly with AR) you just get a defective batch of lenses. Even with the newer AR coats, I have seen this happen.

[Aarlan]

If your friend is using metal blocks on a horizon, tell him to use the black flatter blocks and turn down the chuck pressure to about 50psi. This will cure the problem.

It's not a horizon, if I'm not mistaken. I used a horizon, and he has another dry cut...I'll ask him what he's using.

AA

[Aarlan]

Cleaning solution may be the cause ?

He told me they were in the tray and 3 days later the pt. came in for dispense.

AA

[Aarlan]

I haven't seen stress cracks on lenses in zyl frames. Is this person putting an appropriate safety bevel on the lenses?? Where are the cracks located? Nasally, Temporally???

Don't know actually.

AA

[fjpod]

Hi Aarlen,

I would guess it is the blade. I use the old Horizon II and I really stretch the life of the blades for CR-39 but I learned never to skimp with Poly and High Index. If I have one poly to edge I will change the blade and then change it again for CR-39.

I haven't seen stress cracks on lenses in zyl frames. Is this person putting an appropriate safety bevel on the lenses?? Where are the cracks located? Nasally, Temporally???

I'm using the 7E. I agree with you 1000% on the blades. I have never seen poly stress cracks along the bevel in a zyl frame or even a metal frame. I've not even seen stress cracks in drill holes with the 7E.

It's gotta be a dull blade "pulling" chunks of poly off the lens, leaving a split surface. We use the "disposable" blades which we run for about 300 cuts. We use about 50% CR and the balance is poly and hi-index.

[Ed_Optician]

THe horizon does have a good poly cycle but you can slow it down even more. I would set the machine 5mm oversize then take it down 1mm at a time til on size that should l;ower stress on the lens during edging. Use black chucks for higher - Rx or the equivalent plastic chuck. Use sharp blades in a high CR-39/high index market 1000 on hte resettable counter is about right. I am talking about the carbide inserts that Optronics retrues for you 2 sharpenings then replaced. If you can get them the diamond blade that optronics offers may help on poly too

Ed

[Aarlan]

I'm not sure how much I should be helping him, since the more folks he irritates, the more they'll come to me...Maybe I should recommend cleaning them with acetone...

That brings up another issue. I have an optician down the way that often needs help edging jobs in a pinch (he has no edger). I'm happy to do it, even though we are technically competitors. I don't have any problem doing it, but someone asked me why the heck I would help a competitor. Does anyone else out there help other professionals in your area when they are stuck? Order frames for them if they don't have an account, edge or tint a job or the like? Or is it just me being a good optician and a horrible businessman again.


AA

[For-Life]

why can't you charge him edging fees?

[Aarlan]

I suppose I could. Maybe a couple of bucks

AA

[popeyes]

The good you do in life will be rewarded ten-fold, even if its just knowing that you've helped someone in need. It may not enrich your pocket but it will boost your self esteem!