Protection to ARC lenses

**sandeepgoodbole** · 05-24-2002, 01:48 AM

Protecting ARC lens from scratching due chuck marks or hand while Grinding is a big question.
What are the methods to avoid it ?

**JERRY HUANG** · 05-24-2002, 06:41 PM

In the old day, My formal supervisor taught me to place a layer of masking tape over the coated lens before edging. The blue type is avialable from Coburn.

**mleamaster** · 05-31-2002, 06:28 PM

I have used a standard blocking pad on the minus side of an AR coted lens very successfully. You want to avoid too much chuck pressure also as that can cause it's own set of problems. After edging be sure to rinse the lens off thouroughly. Any particles remaining after cutting can be deadly to the lens.

**Duane Metcalfe** · 06-04-2002, 07:31 AM

As stated before, use edger dots...blue 'surface saver' type tape cut specifically for edging and the like...available from any lab consumable supplier.

Duane

**mleamaster** · 06-04-2002, 06:01 PM

Actually the blocking pad will offer a little more protection than the blue tape will. The pad has more cushioning which helps protect the coated lens. It's best to leave the blocking pad covering on the chuck side, otherwise the pads adhesive will really stick to your edger's chuck.
Remember, one of the worst things you can do to an AR coated lens is stress/flex the lens. It will almost surely result in a coting striation or crack. High index lenses are by the way, more susceptible to this type of damage.

**Specs** · 06-04-2002, 06:53 PM

As mentioned earlier, I put a blocking pad (leap pad) on the minus side, but on the plus side where the block is placed, I use 2 pads for thickness to keep that block away from the lens.

**j_gustafson** · 06-04-2002, 09:53 PM

I use a Santinelli edger which does not allow me to adjust chuck pressure. Adding extra leap pads to each side of the lens does help reduce strss when edging 1.0 Hi Index lenses.

**Jubilee** · 06-05-2002, 09:59 AM

We were having a big problem with stres cracking on the Gentex Profiles. What worked for us was using a blue chip (the tape specific for edging) on teh back side, but we got a different chuck for our edgers. We have the professional and was able to get a chuck that was around 25 mm in diameter, with a rubber cushion instead of the metal rod for the length to where it attaches on the shaft assbly. So far it has worked really well. It take only a couple fo seconds to pop off the standard chuck, and to place this one on. So far since we switched to it, we have had no stress cracks on the profiles nor on the pentax lenses we use.

Cassandra

**jwolf** · 06-05-2002, 02:46 PM

A leap pad on the back of the lens works great, as it provides a cushion. Make sure you leave the paper on the leap pad so you don't pull the "O" rings off the chuck if your edger has them.

You will want to check your pressure as it is usually the culprit