CAD/CAM
One factor that may be driving the development of improved stone-in-place technology is the need from some jewelry customers—including high volume buyers such as big-box retailers and home shopping channels—for lighter product with bigger stones. “They’re all demanding that everything be half a gram with half-carat stones in it,” say J. Tyler Teague, president of JETT Research in Johnson City, Tennessee. “As the requirements get lighter and lighter, you have to be able to fill the parts.” Because of this growing trend and the precise measurements required to produce successful product, it may come as no surprise that more and more models are being designed using CAD software. While initial designs may be done by hand and even preliminary models created the same, creating a model in CAD or transferring a design into the software allows for minute control over every dimension. And when the difference between success and failure can come down to the matter of a tenth of a millimeter, CAD becomes indispensable.
“A lot of people think you can just hand-make a model and be precise enough to wax it on a production level,” Teague says. “You might be able to get lucky, or if you overbuild the prongs, you could do it. But to me, to get good wax setting, you almost have to make the models in CAD. When prong setting, you can really plan out how thick the prong is versus the depth of the seat. That’s so critical to production wax setting.” And the smaller your stones, the more you need CAD’s precision. “If you’re setting stones that are 2 mm in size, and your inside dimensions are supposed to be designed for a 2 mm stone but you’ve got a variance of 2 mm to 2.1 mm—when it comes to [a stone this small], 0.1 mm is a big number,” Teague explains. “When you’re working with a 5 mm stone and you’ve got a variance of 0.1 mm, that’s not even significant. But as the stones get smaller, the space between the prongs and the size of the prongs is hugely critical.”
Two techniques where this technology becomes virtually critical to success are channel setting and invisible setting. “One of the most critical aspects of channel-set stone-in-place designs is the gap between channels,” says Ajit Menon of United Precious Metal Refining Inc., in Alden, New York. “All gemstones will have some slight variations in their sizes, so it is very important to maintain safe and tight tolerances on the channel widths. Too tight a grip will shatter or crack the stones when metal shrinks after casting. Too large a gap will result in loose gemstones that fall off during the manufacturing process. CAD is the only way to maintain these precise dimensions in your models.”
Where CAD really shines is in invisible setting, says Eddie Bell, president of Neutec USA in Albuquerque, New Mexico. “Its precision really helps to create good product,” he adds. “You’ve got a network of egg-crate shapes, so to speak. It can be done by hand, and the stones can be set by hand, but it’s time consuming. CAD/CAM really shortens the time it takes to make that kind of model.” The final word on CAD, according to Teague, is: yes.
“If you’re not yet using CAD to create production models, you need to get on board. With hand-set models, there’s just too much variation.” If you’re still not convinced that CAD/CAM is the way of the future for stone-in-place, just check out your overseas competition, says Menon. The technology has spread widely in parts of the world where stone-in-place is prevalent. “Mostly all large stone-in-place jewelry manufacturers overseas use CAD/CAM or stereolithography technology to make their models,” Menon says. “I have seen over a hundred of them in India.”
For those small-scale manufacturers interested in trying this casting technique but not prepared financially to delve into CAD/CAM, SRS Ltd. of Riddings, Derbyshire, England, has developed a new product called Clickset, which purports to make wax-set casting quick and easy. Clickset is a series of pre-formed metal jewelry components. The forms are assembled or soldered together to create a master model. From there, a wax is made and the process continues as normal. Each of the forms is pre-shrunk and pre-cut. (For more information about these products, visit www.srs-ltd.co.uk/clickset/Technical.)
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