Could it be the Trivex?

[NCspecs]

I'm noticing a strange pattern of twisting when I am edging on my Santinelli Lex 1000. It seems to be mostly Trivex (always A/R, I do few jobs without) and it seems to be an issue with plus lenses. It's sometimes just one lens and sometimes the pair are spoiled. I haven't started collecting data just yet to nail down a very specific hypothesis but 4 similarly ruined jobs in a month spells trouble to me. I use standard issue 3M leap pads for blocking, occasionally I've used the pads sent by my lab for specific coatings such as EX3 and Purecoat but usually don't have an issue and the last few jobs had Crizal Avance on them. The edger was checked within the year to calibrate the chuck pressure. I use the ice tech digital blocker and I firmly believe in "slow and steady wins the race" when I am edging my own jobs. Anything I'm missing here?

[Wes]

Trivex is a lot tougher than most other materials, or at least it's tougher than anything else I've cut. I'm not familiar with that machine. Does it have a "trivex" materials setting? When cutting down materials that tend to slip, I cut them down in stages. For instance, if it's a 48 eye size, I may cut it down to a 52 mm circle, check to see if it twisted, then cut it to shape, leaving the size a couple mm larger, and re check for slippage. For really thick pluses, you may want to increase the chuck pressure: it shouldn't craze the AR on a high plus; high minus, it may.

[mdeimler]

Yup...what Wes said. Edge/crib them bigger, deblock, reblock and edge on size to prevent problems like this with Trivex

[nicksims]

I also use the Lex 1000 and the ice mini.
When you say "standard issue 3M" pads, are you speaking of the 1712NR? 1,000 per roll as opposed to the 1712N which comes 10 per plastic sheet. I run mostly slick a/r's and Trivex sometimes. It sounds like you use the "soft" setting- good. I've learned that if you are using the 1712N, they are specific as to which side touches the lens versus the block whereas this is not the case with the 1712NR. Could this be the issue?

I forgot to ask if you are using the high curve blocks with the ridges?

[CoolOptician]

We had a different patternless edger as well. On high powered lenses with Trivex edging, my husband said that he used the lens saver dots front and back, in addition to the 3M pads. He would cut the lens not more than 5mm at a time, and that way you can take your lens out and check for any rotation, and can re-lay it out if it still slips. The other thing he did with Trivex, on high powered lenses, was to clean the hogging and finishing stone after every cut. That helped to eliminate the rotation and preserved the shape of the lens (eliminates the rounded corners that can happen with such a hard material). We dispensed Phoenix only in three piece mounts, for over 11 years, and never had a lens break or starred holes. We had a man run over his rimless trivex with his 19,000 lb bucket truck. Broke an endpiece on the frame. Nothing else. To us, it turned rimless into tough, sturdy glasses, and was worth the extra trouble with edging.

[fjpod]

unusual for a high plus to twist...

in my mind, it's always a dull cutting surface, unless proven otherwise...

are you using blocks with a steeper curve to match the plus lenses? Full blocks or half?

[NCspecs]

unusual for a high plus to twist...

in my mind, it's always a dull cutting surface, unless proven otherwise...

are you using blocks with a steeper curve to match the plus lenses? Full blocks or half?

I am kind of curious about the cutting surface but since it's a fairly new edger and we pay for regular maintainance I didn't immediately go to that conclusion when I started to hypothesize about what the issue may be. I actually do make a point of using the steep curve blocks, they are half blocks though.

I am amazed that I didn't think to edge big and work down the job incrementally to avoid spoiling lenses. What a forehead-slapper! Thanks everybody, what a great, useful thread this turned out to be! I appreciate all the problem-solving.

[Flux3r]

I'm actually having the same issue with my LEX1000, but it seems specific to FT28 bifocals. i know my chuck pressure is set to 160, but other than that nothing seems to be out of the ordinary. i use the 1712NR pads, and even use the slip disks Younger sends us. I'm relatively new to this, so any advice would be greatly appreciated.

[Craig]

I do 95% trivex for the past 7 years with Santinelli and no slippage on anything once you get a new roughing wheel from Santinelli for trivex. It works better on all materials and is only a few hundred bucks and takes 5 minutes to change out.
I guarantee this is what is causing the problem and ft-28's are the hardest get get right. We now get them 100% and never use the slow setting.

[Barry Santini]

I have found the reformulated Super-hydro spray from Optisource to be excellent on difficult trivet FTs. Expensive, but high confidence in the edging results.

B

[Stan Tabor]

This could be the opening line of an optical remake of this song by the Irish Rovers...

https://www.youtube.com/watch?v=nVPu5v_S0Lk

On a serious note, get the roughing wheel talked about in this thread and a previous thread by Craig and forget about it.

[Tallboy]

I clean my wheel with a copper brush at the first sign of trivex gunk causing slippage, though I have a "new" 9000 without the godsend roughing wheel with holes and only cut about 25% trivex in house (most of my trivex are drills and I currently am sending them out to my beautiful drill lab), usually those trivex I cut are plus lenses and a lot of those are ft transitions.

My roughing wheel is only a year old though, so maybe that is your problem?

I only use the 1000 roll 3ms on the worst of the worst slippery ars, and am thinking about trying the optispray.