ask the labs

Best Practices

Susan P. Tarrant

STAYING STRESS FREE

Q When fabricating and mounting drilled and grooved rimless lenses, which lens materials and techniques are best?

A When it comes to drilling:

■ Drill bits should be sharp.

■ Drill speed and peck rate should be optimized for each material.

■ Drill hole placement and size should be accurate, and the angle must match the front curve of the lens.

■ Chamfer holes before assembling.

■ Use tools designed for assembling rimless frames.

For setting grooves:

■ Cutters must be sharp. Grooves need to be inspected under magnification on a daily basis and the cutters changed at the first sign of wear.

■ Groove depth and width must match frame.

Trivex and 1.67 are the best materials for three-piece and grooved lenses. A 1.60 material is acceptable for compression mounts and traditional grooved frames, but should be avoided with notched rimless, metal groove frames, or anything that puts additional stress on the lens.

That said, 40 percent of what we drill and groove is polycarbonate. Following the above procedures gives you the best chance of success after dispensing. However, you still will have an occasional issue with polycarbonate because of exposure to keytones such as acetone, nail polish remover, and Loctite, to name a few.

— Paul Zito, president, Encore Optics, South Windsor, CT

OOH, THAT SMELL

Q Do you have any tips for dealing with the smell from edging various lens materials, particularly high-index?

A Dealing with odors from highindex products is tough. When we generate those materials, we vent the machines outside with dust/mist collectors. It’s not a 100 percent cure, but it sure helps a lot.

For finishing, we try to use dry-cut edging whenever possible on these stinky materials. Wet-cut edgers are more complicated because of mist collection and the need to vent to the outside (which also tends to vent your A/C or heat). With our dry-cut edgers we use self-contained vacuum systems for each machine.

To help to control odors, especially in smaller labs, put clothes dryer sheets inside the collection bag or around the filter. They have to be changed regularly, but it does help.

— Jon Jacobs, vice president, Superior Optical Lab, Ocean Springs, MS

If you have a question you’d like to have answered in Ask the Labs, send it to Susan P. Tarrant. Email: Susan.Tarrant@Springer.com. An archive of past Ask the Labs columns can be found on the Eyecare Business website at EyecareBusiness.com.