See Derby Run! Faster!

The majority of uses for additive manufacturing (AM) aren’t likely to bring a tear to your eye, unless you just really love parts manufacturing. While figuring out new ways to build rocket engines using AM is impressive, it doesn’t really cause much in the way of warm fuzzies. Everyone loves a dog though, right?

It was about this time last year that Rapid Ready first reported on Derby the dog. Poor Derby was born with a defect that resulted in small forearms (forelegs?) and no paws. While the defect didn’t keep Derby from getting around the house, it did cut down on his outside play time. A collaboration between 3D Systems (3DS) and a certified orthoist resulted in a set of prosthetic legs that allowed Derby the chance to run and play on the grass, rather than just on the carpet.

Those legs were just stage one of the Derby project. When strapped onto the dog, the prosthetics looked kind of short, and gave Derby a head down, hunched appearance. His owner, Tara Anderson, a 3DS employee, intended the first set of legs to act like training wheels for Derby, to get him used to the idea of something being strapped to his body.

After Derby showed that he was fully comfortable with his new prosthetics, Anderson and 3DS went back to work to develop Derby 2.0. This time the legs would be scaled to provide Derby with his full height, as though he were actually standing on his own two legs, allowing him to look straight forward without cocking his head.

The original plan was simply to build an extended version of the blade-like prosthetics Derby had gotten used to, but that idea ran into a problem. When Anderson strapped them to his legs, instead of running around like he had the first time, he continued to lie on the ground and shook his legs like he was trying to get the things off. That reaction led the design team to go back to the drawing board.

Derby’s new legs developed into a kind of spiral design that included knee-like structures to give as realistic a feel of true legs as possible. In order to provide a little extra spring for his step, the new legs were also printed from nylon, using selective laser sintering. When the new set was strapped on, the team was rewarded with a wagging tail and soon enough Derby was off, running and playing just like any other dog.

“I can’t imagine tackling this case without 3D printing,” said Tara Anderson, 3D Systems’ project lead for Derby’s prosthetics. “The key to our ability to help Derby was being able to quickly and fluidly move from design to verification to end-use part, and back to design without losing any momentum. We were able to adapt our design to suit Derby’s evolving needs in real-time.”

Below you’ll find a video about Derby’s new legs.

Source: 3DS