If you’re a bench jeweler who loves her flex-shaft, you may consider adding a micromotor to your toolbox. That’s what San Francisco–based jewelry artist and Revere Academy instructor Ronda Coryell did recently when she purchased a Foredom K.1050 brushless micromotor—and it’s since become one of her favorite tools in the shop.
While the flex-shaft delivers high torque at relatively low rpms, providing maximum cutting ability with maximum control, the micromotor delivers high speeds (up to 50,000 rpm compared to the flex-shaft’s 15,000 rpm) with less torque. It’s brushless and features a supple power cord that makes it light and easy to use. While Foredom’s micromotors won’t do everything the flex-shaft does—they won’t take larger buffs, nor are there as many accessories available—the faster speed provides a smoother cut. This is especially useful for fine detail work; for example, a jeweler can run a 0.5 mm round ball bur at 50,000 rpm smoothly enough to sign his or her work.
One reason Coryell has largely switched to the Foredom K.1050—which she calls the “Lamborghini of micromotors”—is because vibration in the handpiece has been eliminated. The vibration can cause a bur or bit to “wobble,” she says. “If a bur or bit goes true and dead center, it’s one thing. But if there is vibration or wobble, it makes a different type of hold. The micromotor just offers more precision.”
She also likes the control box that comes with the K.1050, which allows her to choose forward or reverse, set a fixed speed, work with the variable-speed foot control, or opt for “cruise control.” The last is by far the coolest option, says Coryell, and it works much like the cruise control in a car. You hold the cruise control button and bring the foot control to the speed you want. When the control beeps twice, you take your foot off the pedal and cruise. To take control of the speed again, you simply tap the foot pedal. Just as the cruise control in a car allows you to rest during a long drive, the cruise option on the micromotor allows you to rest if you have a lot of metal or wax to remove.
Coryell’s favorite handpiece for the micromotor is the reciprocating hammer. Unlike most hammer handpieces, the K.1050’s starts only when you press it to the surface, so you can position it precisely before starting. In addition, you can adjust the stroke intensity—from soft to hard—and the striking speed to your liking. You can tap something only once if you want or need to. While you can use the reciprocating hammer for texturing metal, says Coryell, she finds it most valuable for stone setting, especially bezel setting. “It’s the most amazing hammer handpiece,” she says. “I can’t imagine what I’d do without it. It’s so controllable.”