Alize Lenses Twisting off Axis.

[edKENdance]

Seem to be caught between a rock and a hard place here so I was hoping you folks could help me. We receive the uncuts with the blue Azure on them. We follow procedure to the letter. Still they twist (5-15 degrees). This occurs predominantly with lens with a small ct. We are using Spartan edgers so we can not control the pressure settings. We've had problems in the past with crazing on these types of lenses so we use the light pressure setting. We think this could be the problem. We just started using the medium pressure on these jobs but we risk crazing. That's the rock/hard place thing.
Anyone know of similar problems or can offer any sollutions? Thanks.

:cheers:

[For-Life]

Seem to be caught between a rock and a hard place here so I was hoping you folks could help me. We receive the uncuts with the blue Azure on them. We follow procedure to the letter. Still they twist (5-15 degrees). This occurs predominantly with lens with a small ct. We are using Spartan edgers so we can not control the pressure settings. We've had problems in the past with crazing on these types of lenses so we use the light pressure setting. We think this could be the problem. We just started using the medium pressure on these jobs but we risk crazing. That's the rock/hard place thing.
Anyone know of similar problems or can offer any sollutions? Thanks.

:cheers:

First thing, do not clean the lenses under after you cut them. With the azure it is only on until you clean them and then it comes off.

If you are already following that may I suggest using a piece of transparant tape between the chuck and the lens. I used to use it on the ICE lenses if the lab forgot to send their stickies. The only thing is if you use this trick edge them right away, because after 15 minutes the tape stops working with it.

[edKENdance]

Thanks for the quick reply. Rest assured we are not cleaning the lenses beforehand. The tape idea has merit but I'm a little concerned about smudging or obscuring the axis dots. If you have to take the tape off than you're screwed too.

[Monkeysee]

Have you tried taking the blanks down in size on your hand edger before laying them out?

Strange that they aren't cooperating, (I have a gamma edger and haven't had any problems with these-but have a fragile lens setting---once I forgot to use it with a pr. of these though and they still came out fine?)

[edKENdance]

<b>MonkeySee</b> That's a great idea. Have you encountered any problems with the topcoat? Is this what you did to remedy it?

[Monkeysee]

<b>MonkeySee</b> Have you encountered any problems with the topcoat?

No, not with these, the overcoat that's applied so you can edge these lenses can be hard to clean off though-elbow grease required! I follow the technical bulletin essilor sent me and have had no problems.
Also have edged some ICE lenses successfully, after they finally sent out a bulletin, follow the same procedure pretty much for both lenses, (except for the stickers ICE lenses require)........never did try hairspray as was suggested on an earlier thread.....
:cheers:

[edKENdance]

The stickers for ice are pretty similar to the tape idea? Any problems with crazing at higher pressure?

[Thumbs]

To help see the lensometer dots better and without smudging the dots, I use and opaque ink marker and superimpose the dots to the back side of the lens. The opaque ink dries immediately and can be removed with alcohol. Opaque ink is simply put, white-out ink. Pens can be purchased at any office supply, craft or art store. They come in many colors, I prefer white, but do not purchase gold or silver because they have bits of metal in the ink and will strach lenses when removing. I, too, run Kappa and Gamma edgers and have no slippage when using the fragile cycle. You should also make sure the right-side rubber chuck in the edger is soft and plyable and not dried up and hard. If so, you can try cleaning with alcohol to soften or replace with a new one.
Hope any of this helps!!

[DPalmer]

Here is what we do we also have Spartan edgers.Double pad your blocks,use the light pressure setting put a leap pad on the back of the lens and take a replacement chuck pad for your large chuck and put it on your halfeye chuck.Seems like a bit of a pain at first but it works like a charm.That should do the trick if it doesn't i will be very shocked but it should solve your issues with crazing and axis. GOOD LUCK. Let me know how you make out.
Dan

[Optical1]

To prevent twisting and crazing (or ghost image) of Alize set edger on low pressure. Use a clear Dac edging for coated lens mask on front surface of lens to prevent twisting. Also, use a solid inside surface finish block from Precision Tool(do not use a block that has a circular cut-out or identation on inside surface). Also, use a solid blocking pad from DAC for blocking. Do not use a blocking pad with a small center cut out of the middle. Apply one of these solid DAC pads to the inside surface of the lens also. It is critical that you use the correct curve block for each Rx. This should eliminate the twisting and crazing of Alize.

[shellrob]

Our edger has been doing the same thing, but mostly with the polycarbonate lenses. I actually called the lab and asked them what they do since they use the same edger as us and they actually told me to spray the lens before hand with hairspray. Aqua net to be exact. It works most of the time but I find I still have problems after trying everything mentioned on this board. It's frustrating.

[edKENdance]

Shellrob, thank god for your post! I thought we were the only ones. Everybody's advice has been greatly appreciated :cheers:
I've implemented a couple of the ideas here and we had no problems yesterday. Mind you we only had a handfull of ultra jobs. We had one high index +7 with a -6.75 cyl that we even had to deblock and redot but it came out perfect.
I'll update this thread as things occur.

[shellrob]

I know how you feel. I do find that the higher the rx, the higher the chance of it slipping or breaking. I haven't tried double blocking though.


PS....man, that's a lot of cyl.

[Optical1]

Let me clarify my earlier post. Front surface of lens: to prevent twisting, first put a special DAC clear lens mask for coated lenses on front of lens. This DAC mask was created to stick to ultra slippery surfaces so lenses would not twist in edger. To prevent crazing use a solid finish block from Precision Tool(your block can not have any cut-out or identation in the center, it must be flat.(These flat surface blocks are available for different curves, make sure you clock your lenses before blocking and use the block that matches the curve.) Apply a solid blocking pad from DAC to the solid block. Make sure the pad you are using does not have a small circle cut out in the center like most do.
Back(Inside) surface of lens: put another DAC solid pad on the inside surface of the lens so front and back of lens are balanced. I had problems originally with crazing of Alize poly stock lenses because of thin centers, but since I have started blocking this way I have not had any problems.

Other posts mentioned hairspray. Hairspray to my knowledge was only recommended if the protective top coat(which is applied so the finish block will stick to the lenses for edging) was accidently wiped off or if lenses needed to be re-blocked for any reason.

[shellrob]

When I order uncuts from the lab with the ar on it, I was having a very difficult time edging them. They sent me the clear pads to use with our current blocking pads and that should do the trick. Well, it did on most of the jobs, so I noticed that it was still slipping on the high rx's and the poly lenses. So, I called the lab and asked them what I was doing wrong or what could I do to fix the problem, as you all know, my breakages were an expensive fix. Anyhow, that's when they told me to spray the lens with hairspray and let dry before blocking. It has worked on most jobs, but not all the time with the high rx's and poly lenses.

Optical 1: no one has told me about the different blocking pads or the different blocks. I'm going to have to try, as I don't know what else to do and sending those particular jobs to the lab defeats the whole purpose of having an edger to begin with.

[fjpod]

see my response to post: Surpass AR

[Judy Canty]

We're very satisfied with the Crimson King blocking pad from OptiSource.

[eromitlab]

Here is what we do we also have Spartan edgers.Double pad your blocks,use the light pressure setting put a leap pad on the back of the lens and take a replacement chuck pad for your large chuck and put it on your halfeye chuck.Seems like a bit of a pain at first but it works like a charm.That should do the trick if it doesn't i will be very shocked but it should solve your issues with crazing and axis. GOOD LUCK. Let me know how you make out.
Dan

I do the same thing with the leap pads when I edge certain fragile and slippery coats on my Triumph and have had no problems to speak of. It also helps if you only use black colored (i.e. semi-tec) or whatever flat curve blocks you might use when using a small clamp pad.

The reasoning behind this is that the small clamp pad pressure zone is about the same as the contact the block makes with the front surface; and therefore, the lens does not bow or twist enough to craze the coating or knock it off axis by too much. I didn't come up with this method (one of the fellas I apprenticed with did), but it hasn't failed me yet.

hope you have better luck in the future, edKENdance.

[edKENdance]

oh, thought I posted this already. Turns out the problem was not with the lens, it was with the edgers. Apparently the Spartans we are using have a bit of a design flaw that causes lesnses to be edged off axis. This compounded the confusion as we had just started to edge these lenses around the same time.

[DPalmer]

Please tell me more about the design problem in the Spartans and how you were able to fix it

[Refractingoptician.com]

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[egbert]

Hi guys -


I spoke to our lab about this. They said they rough cut the lenses 10 mm too big, then re-block, and re-cut. ( I know, it's a second step, but they said it helps avoid re-do's.)

egbert

[Chris Ryser]

Hi guys -
I spoke to our lab about this. They said they rough cut the lenses 10 mm too big, then re-block, and re-cut. ( I know, it's a second step, but they said it helps avoid re-do's.)
egbert

That has always helped...............and was used widely during the glass area. Coburn even had a special roughing edger for this purpose.

[QDO1]

some of the newer generation of edgers have 2 wheels that work against each other. this reduces slippage to zero!

[Chris Ryser]

some of the newer generation of edgers have 2 wheels that work against each other. this reduces slippage to zero!

That seem to be a good idea...............but how do you explain the wheels working at opposite sides side by side, and a thin edge lens sitting in the middle (gap) of the 2 wheels ?