solutoin for cracks around the holes of poly lenses

[Jamesye]

Hi all,

I sold a 4 point mounted glasses with poly lenses for my customer.
After two weeks, she found some cracks around the holes.
I replaced the new poly lens. three weeks later, she came again. I found the same things happened.

Do you meet the same problem?

Could you give me any solution?

Thx lot

James

[optical24/7]

Drill Seal

http://optochemicals.com/


* don't work or profit from the above....unless Chris wants to send me some micro-tints :D

[chip anderson]

Either drill seal, or use Trivex/Phoenix.

[Chris Ryser]

Do you meet the same problem?

Could you give me any solution?

Thx lot

James

Vision Ease, manufacturer of polycarbonate lenses says:

http://www.vision-ease.com/product_specs/LensDrillRimlessMounts.pdf

and here are the details on "Drillseal"

http://optochemicals.com/products/info_drillseal.htm


use it right and have no more problem with cracking holes.

[HarryChiling]

Also chamfer the holes, and don't use drill seal use the edge polish Chris sells it's a bigger bottle and it works the same, sorry Chris. ;)

[Chris Ryser]

Another useful product for polycarbonate, also cost's more Harry

http://optochemicals.com/products/in...dge_polish.htm

[HarryChiling]

Another useful product for polycarbonate, also cost's more Harry

http://optochemicals.com/products/in...dge_polish.htm

It does cost more for the edge polish but it's also a much bigger bottle, anyway either way you go you can't really lose and both will work the same.

[Ocular Dexter]

You have to watch out for solvents issues when dealing with poly. Also, make sure your bits do not need repacing.

I would just use trivex, that way you don't even have to worry about it.

[HarryChiling]

You have to watch out for solvents issues when dealing with poly. Also, make sure your bits do not need repacing.

I would just use trivex, that way you don't even have to worry about it.

Great Point. :cheers:

[MarcE]

Use Trivex:

Forget to chamfer the holes? No problem
DOn't have any nylon washers? No problem
Drill bits dull? No problem
Overtightened the nut? No problem

Use Trivex and fugedaboutit.

[Happylady]

Trivex is a great material for drill mounts but Trivex can get thick in stronger prescriptions. Also it comes in very few progressives.

What about 1.67 or 1.70? Aren't they less likely to crack around the drill holes?

[APV Optical]

I have found Chamfering the holes and drilling perfect works just fine. Chamfering makes a huge difference as it rounds off all of the rough edges where solvents from cleaning the lenses will go and seep into the lenses therefore causing cracks/splitting in lenses

[AWTECH]

Trivex is a great material for drill mounts but Trivex can get thick in stronger prescriptions. Also it comes in very few progressives.

What about 1.67 or 1.70? Aren't they less likely to crack around the drill holes?

FYI: ICE-TECH makes a great backside Individualized PAL, so there is one you can add to your limited list. Our technology produces thinner lenses than a molded PAL. Slightly thicker Trivex in most cases is still a lighter weight lens, or at least the about the same weight for the same Rx. The specific gravity of Trivex is much less than 1.67

[Thumbs]

I have found Chamfering the holes and drilling perfect works just fine. Chamfering makes a huge difference as it rounds off all of the rough edges where solvents from cleaning the lenses will go and seep into the lenses therefore causing cracks/splitting in lenses

Don't forget, that when you chamfer the holes to use the proper chamfering tool and not a tapered file. The chamfering tool will only chamfer the inside edge of the hole and the tapered file will file the edge and into the hole. Because you chamfer both sides of the lense, using a tapered file wil give the inside of the hole a pointed hour glass shape. Which will eventually wear and the lenses become loose, especially in screw mounted rimless.

[Dougfir8]

I have a -4.75 Sph with little cyl. The drill mount Trivex lenses are two years old, and just recently they developed small cracks. I need a new exam anyway, and it's time to try the new LifeRx Illumina.

[Ginster]

You can use Hi-Index 1.60 it has the same tinsle strength as Trivex, 1.67 to 1.70 is not recommended. We only use this when Trivex would be to thick and never had a Problem, the labs usually will warranty for drilling.:)

[Ocular Dexter]

You can use Hi-Index 1.60 it has the same tinsle strength as Trivex, 1.67 to 1.70 is not recommended. We only use this when Trivex would be to thick and never had a Problem, the labs usually will warranty for drilling.:)

The only material that has a similar tinsle strength of trivex is poly. I don't see any major issues with 1.67 and drill mounts.

[RT]

Please note that there are multiple lens materials that happend to have an index of refraction close to 1.60. Yet these materials are chemically and optically very different, including the tensile strength. Some 1.60 materials have much higher tensile strength than others.

Do not fall into the trap of assuming that all 1.60 materials are the same.

[Chris Ryser]

Do not fall into the trap of assuming that all 1.60 materials are the same.

That is correct.....................but it is not the material that is the culprit of rimless mountings to crack............it is the way of doing it.

When I had my lab we mounted everything in glass lenses and had no problems even on the flint lenses. With technology so advanced we can see that the good experienced fingers that have the touch do not exist anymore. :hammer:

[HarryChiling]

Has anyone compiled the data on tensile strength? And if so how do I get it?

[Barry Santini]

Use Trivex:

Forget to chamfer the holes? No problem
DOn't have any nylon washers? No problem
Drill bits dull? No problem
Overtightened the nut? No problem

Use Trivex and fugedaboutit.

Marc, I have to say that I agree with you. Alot of mounting have exposed notches and holes. Drill seal, when applied to the notches, will often run off onto the outer edge of the poly, thereby creating a "smeared" edge/polish.

Trivex is the way to go where the mountings show sensitivity to poly fracturing.

Otherwise, its Silhouette bushing-mounts for me.

Barry

[optical24/7]

Has anyone compiled the data on tensile strength? And if so how do I get it?

Something like this?

http://www.optiboard.com/forums/show...nsile+strength

[chip anderson]

Of course one does see a posting here about someone's trivex getting cracks around the holes.

Chip

[Chris Ryser]

Has anyone compiled the data on tensile strength? And if so how do I get it?

chip anderson
Master OptiBoarder
Occupation: Optical Retail


Join Date: Jun 2000
Location: Ridgeland, MS, USA
Posts: 7,889



Thesile Strength?
Unless I missed something in science and metal shop classes. Tensile strength=force needed to pull a substance apart from side to side. Not related to impact resistance or scratch resistance. So why do we care or even bother to measure this unless we are making some sort of structure?

Chip

Explanation
The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. The definition of failure can vary according to material type and design methodology. This is an important concept in engineering, especially in the fields of material science, mechanical engineering and structural engineering.
There are three typical definitions of tensile strength:
Yield strength The stress at which material strain changes from elastic deformation to plastic deformation, causing it to deform permanently. Ultimate strength The maximum stress a material can withstand. Breaking strength The stress coordinate on the stress-strain curve at the point of rupture.


http://en.wikipedia.org/wiki/Tensile_strength

[Ocular Dexter]

Please note that there are multiple lens materials that happend to have an index of refraction close to 1.60. Yet these materials are chemically and optically very different, including the tensile strength. Some 1.60 materials have much higher tensile strength than others.

Do not fall into the trap of assuming that all 1.60 materials are the same.

I thought tensile strength was the same as impact resistant. I learned something new, thats why I love Optiboard. My question is what is more important tensile or impact? Look at the youtube video on impact resistance http://www.youtube.com/watch?v=rKEC4zDowXs