May
2004

Well Equipped

Anyone who has ever fabricated a pair of rimless eyeglasses in an in-office lab knows the job requires a higher level of craftsmanship and is more time consuming than fabricating “full-frame” eyewear. The job has grown even more complex in recent years as more rimless styles have been introduced. Yet patients expect rimless frames to be as on-axis and as durable as any other pair of glasses. Consequently, lab technicians must balance the demands of craftsmanship with the need for efficiency.

“There is more artistry involved with these frames,” says Bryan Shaw, owner of The Rimless Connection, a Miami-based optical laboratory specializing in drill-mounts. “But that doesn’t mean you can take forever with each pair of rimless frames. You have to try to maintain a production flow.”

Drilling Lab
The first step in maintaining production flow standards for rimless eyewear may be creating a “drilling lab,’’ a separate space within the finishing lab that is distinct from the edger area and the bench—i.e. frame warmers, and mounting tools for plastic and metal full frames. “A separate drilling lab helps the tech focus on each job because there is more customizing,” says David Finley, lab manager of Dixie Eye Center in St. George, Utah. “It also keeps the tools organized in one place.”

One reason tool organization is more of a production issue is that there are simply more tools to organize. Optical equipment and tool manufacturers have responded to the growing demand and product selection by introducing a range of devices that reduce spoilage risk, thus improving production flow. “Obviously you can’t rush the jobs, but some tools cut down on time without sacrificing the quality,” says Finley.

The centerpiece to the new rimless fabrication lab is the drill. Gone are the days of using a hand-held, all-purpose drill and “guesstimating” positioning and angling of the holes. There are now more than a dozen high-precision, high-speed optical drills available, most priced between $1,500 and $5,000, that can ensure proper hole positioning so the lenses remain on-axis. In addition, the drills allow the operator to set the angle of the drill bit as it enters the lens so it conforms with the lens curvature, thus maximizing hole integrity. The mounting hardware can then be affixed flush to the lens surface so it does not compromise the stability of the mount.

“With the amount of rimless styles, both in volume and type, you need a system,” says Richard Homeier, owner/optician of Optical Perspectives in Estes Park, Colo. “The new drills take away the guesswork and helps in creating a system.”

Most of the new drills drill lenses with the edger-chucks in place. “This gives us an extra reference point,” says Amy King, lab manager of The Eye Place, Birmingham, Ala. “The lens stays on block, so if you edged the lens on-axis, you will drill the holes on-axis.”

An extra set of bits is an investment in-office labs are making to ensure production flow and low spoilage. “The bit should go through the lens like a hot knife through butter,” explains Daniel Seltzer, owner/optician of Optical Effects, Inc. in Tampa Bay, Fla.

“A dull bit is slower. You notice heat build up on the lens. You have to replace the bit right away, because it will just get worse. It creates stress cracks that will spread over time. I keep a complete extra set of bits, at least the ones I use most frequently.”

There is less sizing of the hole required due to the variety of drill bit sizes. What technicians discourage is making the hole bigger, even by a fraction of a millimeter, by post-drill filing, because in general the hole interior and exterior openings will not be as uniform as when they are made with a sharp, specification-sized drill bit. But drill-bit size accuracy does not preclude post-drilling filing to enhance hole integrity.

“I touch up everything with a file just to make sure,” says Shaw. “If I am smoothing it too much, it probably means the bit is dull and I will change it. Even with the notches, I make a few swipes with a file.”

Clean Holes
There are two jeweler-like instruments lab techs use for the finishing touch-up work on the drill holes. A “reamer,” which removes excess lens material from the interior of the hole and files or rasps, which can also remove debris but are generally used to ensure a smooth and even interior. Very narrow rasps or files help minimize any of the spider-web cracks sometimes caused by drilling. These tiny fissures, often not apparent to the naked eye, gradually grow into crevices, affecting both aesthetics and frame functionality. “I use a magnifying glass to inspect the holes after drilling,” says Finley. “You want the holes to be clean without any ‘chatter’ around them.”

With the screw and mount assembly, chamfering, sometimes called smoothing tools or burs, are needed to create a bevel around the hole so the head of the screw is flush to the surface of the lens. “I chamfer the holes,” says Seltzer. “This is an aesthetic point because you don’t want the screw head protruding, but it also makes the screw more snug and the stability of the assembly long-lasting.”

Hand-Held Finishing
Tension mounts use plastic sleeves or bushings that encase the tip (or post) of the frame pieces. The tension that holds the eyewear together is created by the compression of the plastic between the frame hardware and the lens. Post-drilling, tension mounts require that the bushing is inserted into the hole then cut flush to the lens surface. The sleeve is then opened so the tips of the frame pieces can be slipped into this plastic encasement within the hole.

In the past, sleeves were cut with a razor blade, then opened with a pin. Some tool manufacturers offer specialized cutters and pokers for a more “surgical” handling of the sleeve.

“These tools are worth the investment,” says Shaw. “Razor blades get dull pretty fast. These snippers go right up to the lens, so there’s little-to-no-risk of slipping. The pokers go right through. You don’t have to work the plastic to open it.”

Rimless frame growth has also meant new additions to the optical pliers family. Rimless adjusting pliers, typified by plastic or nylon jaws, often featuring indentations for screw heads and eye pieces, enable precise fitting alignment and minimizing scratching. “You don’t want to go through the whole process,” notes King, “then scratch the lens when you align the frame.”

With three-piece mounts the lenses play a greater fashion role, simply because there’s less frame. Any scratch is more apparent-increased handling means higher spoilage risk-and by definition, rimless mounting requires increased handling. Using these new tools can decrease the risk of spoilage during handling while making rimless eyewear production more efficient. “Finishing always has more spoilage than surfacing,” says Finley. “With our drilling lab, we are averaging about 25 minutes per job and our spoilage rate is the same as for any other frames.”

RIMLESS PROCESSING POINTERS
1 When ordering a lens, inform your surfacing lab when it is a rimless job. Edges should be no less than 2mm and no more than 5mm. 
2 Test all new frame styles, lens materials and designs in your drilling lab before dispensing the product. 
3 Use sharp drill bits, check with frame manufacturers to ensure you are using the right sized bits for each design.
4 Protect the surface of the lens with surface saver tape, which should not be removed until after mounting and final alignment. 
5 Inspect drill holes. Use reamers and files to make holes smooth, even and free of tiny stress cracks.

 

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