Block burn when edging 1.67 lenses

[marc71]

Hi Everyone,

Lately we have been getting a significant amount of "block burn" when edging our 1.67 (with or without AR) lenses. We use nidek blocks and Optronics 7E edgers. We use the proedge pads and the block burn always occurs on the front side. Any suggestions would be great.

Thanks,
Marc

[PRECISIONLAB]

A similar problem was posted last week..see Blocking Marks..

Has anything changed in your process..ie different blocking pads, lenses from a different supplier..etc

Blocking pad marks are usually the reslut of chucking pressure. In the case of the 7e check your right side chuck to make sure it isn't worn...does it turn without resistance when testing by hand. As you know feed rates and blade quality can cause torque. Try a protective pad to see if this helps reduce front side marks..if not placing in a warm water bath should relax the marks you referenced.

[Reliable Optics]

Do you have the same problem with higher RX Poly?

[Pogu]

We get this very sporadically. I've wondered if it has to do with hardcoat integrity since it would happen in the middle of a bunch of jobs with no problem.

[marc71]

Thank you for the great feedback. We lowered the pressure on the front side and increased the pressure on the back so we don't have slippage. The problem was only happening on the front side and it happens no matter which manufacturer we use. Since the adjustment, things are working well. I will keep you posted.

Thanks!