Using CAD to improve free-heel skiing

By Michael Jermann, Assistant Editor

Jeff found early on that if he had a fall and his bindings released, it was important to use runaway leashes to keep his skis from becoming hazards to other skiers.

Jeff Cox, the owner of Bluebird Day Gear, has always loved skiing, especially telemark. Telemark skiing, often called ‘free-heel skiing’, is a form of downhill and cross-country skiing where the book is attached only at the toe, allowing the heel to come up from the ski.

While gearing up for a run, Jeff noticed that he often had to remove his gloves (or mittens) prior to connecting the runaway leash because the clasp was difficult to manage. After hundreds of times of having to remove his gloves and countless broken clasps, he decided he’d design something that was stronger and easier to manage—with his mittens on.

All modern alpine skis use brakes instead of the old-style runaway leash, but those still using telemark gear don’t always have that luxury, and the clasps on the leashes aren’t convenient to use or strong enough to be safe.

Jeff designed his new clasps using SolidWorks 3D CAD software. “From there it was easy to save the files in an STL format, then have the components uploaded through the computer to Solid Concepts, a service bureau that provided SLS (Selective Laser Sintering) parts for final form and fit testing. SLS is a process where a powdered material like nylon is sintered layer-by-layer using a laser, just as the name implies.”

Jeff tested his design in-house using several materials (aluminum, MDF, plywood, nylon cutting board…) prior to porting over to the SLS machine where the components produced were strong and accurate enough for Jeff to do final tests on how well they worked.

After that, the clasps were made out of stainless steel, rather than the typical die-cast zinc or extruded aluminum components. “The idea was to make the clasp stronger as well as easier to clip on and off while in bulky gloves,” Jeff explained. “The SLS parts worked perfectly for my purposes, and I didn’t have to do any post processing on the parts, either.”

Since that time, he’s also made available a reinforcement plate that helps to protect a skier’s rubber boot sole from wearing out. The plates are for older skis and are not supported by ski equipment companies any longer.

Jeff’s latest project is a durable heel lever that is useful for both touring and downhill travel. For downhill telemark skiing, the cable that goes around the boot provides spring resistance that gives the skier more control over the ski, and all of it comes through the heel lever acting as an over-center lever, keeping the cable on the boot.

His latest design tests are getting him closer to creating an extruded aluminum heel lever with what he calls its “touring mode.” The SLS glass-filled nylon parts provided by Solid Concepts were suitable for a wide variety of testing, which made it possible for him to locate some of the areas that needed adjustment.

Solid Concepts
www.solidconcepts.com