For C.J. Howard, a northern California-based climbing enthusiast, the most important climbing gear is his customized prosthetic foot that he designed with climbing partner and environmental/aerospace engineer Mandy Ott. Howard, a lower-leg amputee, started climbing with his standard artificial, but the prosthesis’ generic shape didn’t work well with the specialized footwear.
“C.J. and I were sitting on the couch, and he said, ‘It would be nice if I could have a foot that’s more suited to climbing,’” says Ott. “So I got out my laptop, opened an engineering CAD program, and on-the-spot created what he described, which was the shape of an aggressive climbing shoe with a downturned toe—like a banana. I just drew what he wanted. It was simple.”
To product the prosthetic, Ott immediately thought of an additive manufacturing process called direct metal laser sintering (DMLS), offered by EOS GmbH, that she had encountered in her mechanical engineering work at a major aerospace company. “I never even thought about fabricating it using traditional machining techniques because that process would result in seams in the foot or there might be nuts and bolts sticking out,” says Ott.
Ott contacted Morris Technologies, an Ohio firm that specializes in additive manufacturing and is the largest deployer of DMLS in the world. Ott said, “They completed the prosthesis just before Christmas, and when C.J. opened his surprise present and saw the new foot, he had a grin on his face that was priceless.”
The material that Morris engineers chose was commercial-grade titanium (Ti64) with superior strength and lightweight, important properties given the intended use. The finished five-pound foot was a single-piece construction, hollow (to minimize weight) and with no seams or fasteners.
Howard has had the opportunity to try out his new prosthesis in the field. His northern California test sites have included the granite of Tahoe’s Lover’s Leap, the single-pitch trade routes of Phantom Spires, sport climbing at Luther Spires, and the crevice and chimney systems of nearby Sugarloaf. He has also climbed with it on dome and crack routes in Yosemite.
“Designing a prosthesis for climbing involves a little bit of trial and error,” says Howard. “Now that I’ve used this one, I know what types of climbing it works really well on and what types it doesn’t.” The first design happened pretty quickly, Ott adds. “Both C.J. and I agree that there are changes that we would like to try out.”