Sanford class uses 3-D printer to create prosthetic hands

Ken Mammarella, Special to The News Journal

By 3-D-printing prosthetic hands, students in Sanford’s athletic training class are learning about math and anatomy, engineering and critical thinking, problem-solving and life among the underprivileged.

Their four prototypes will be sent to a charity that connects people who can't afford prosthetics to those who can print them.

As part of their research, they watched videos of people using mechanical body parts, with a particularly moving one showing a boy so happy at last to be able to draw with coloring chalk.

“He just wanted to be a normal 4-year-old boy,” said teacher Staci Krape. “I cried over them.”

Students in an athletic training class at Sanford School are learning to use a 3-D printer to build prosthetic hands.

The project began in January and quickly revealed something else: history. The earliest prosthetic dates back to the ancient Egyptians – “before time,” as junior Lily Wiesnegger put it.

And the future? “It's amazing how much they’re improving them,” said junior Lindsay Colgan, who was already interested in medicine and is now thinking about a prosthetics specialty. “They’re putting skin on them so you can feel more. They’re making them glow in the dark, like my retainer.”

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The 29 pieces in each hand took 18 hours to print from recyclable and biodegradable plastics known as PLA and PHA (polylactic acid plastic and polyhydroxyalkanoate). The engineering came in with understanding the biomechanics of constructing prosthetics; the math, with adjusting templates.

The students prepared the printed pieces for assembly by sanding off extraneous bits and knocking out chunks on larger pieces that were just for support during printing. Their assembly tools included tweezers, scissors, sandpaper and a Thwack 3-D-printed plastic hammer.

Lily Wiesnegger, 16, a junior at Sanford, hammers parts of a prosthetic hand together made from 3-D printers in her athletic training class.

Onto the problem-solving: Were they following the 10 steps in the right order? Why wouldn’t these precision-made items fit together? Maybe the solution, as sophomore Ryan McKeon figured out, was merely swapping two supposedly identical fingers. And was everything flexing correctly?

And this was just a prototype. They planned to send their four hands to Enabling the Future, a virtual volunteer network that connects people with 3-D printers and people needing hands.

Krape and co-teacher Sandy Sutty expect approval to take a few weeks, and then they’ll customize final versions. They need to add wiring, screws, Velcro, cords and foam to make the hands functionable and more comfortable. Motors are added elsewhere.

Enabling the Future figures these prosthetic hands use $35 in materials. Its e-NABLE network goes back to Washington resident Ivan Owen, who in 2011 created a functional metal hand for a puppet. When a video of it went viral, a South African carpenter who had lost fingers in a woodworking accident sought help. Then a request for a boy born without fingers on one hand. And so on.

The next leap was in 2013, when Owen released open-source, public domain designs. Since then, Enabling the Future figures about 2,000 hands and arms, mostly for children, have been made through its network, with perhaps as many outside of it.

“There are random strangers creating hands for children they will never meet,” enablingthefuture.org says.

15 year-old Lauren Park, a sophomore at Sanford School sands down a piece to her prosthetic hand together made from 3D printers in her Athletic Training class.

“E-NABLE hands open and close using the flexing of the wrist or elbow to create the tension to pull the fingers closed,” the site says. “These devices should be seen as tools and not a fully functional prosthetic device.”

Stronger prosthetics could cost $10,000 or more, according to the site.

At Sanford, the anatomy came into play with students being able to compare their printed hands with the STEM classroom’s model skeleton. And critical thinking rose in importance when students realized the work “was not just on one subject, but combining skills,” Sutty said.

As athletes themselves, the Sanford students appreciate the prosthetics’ potential to the body.

"They really benefit athletes so they can play like any other person,” said junior Lexi Fotakos.

And they have potential for the brain.

“I never pictured playing without all my limbs,” sophomore Kendra Warren said. “When I learned about other people adjusting, it was mind-blowing.”

(left to right)16 year-old Lindsay Colgan, and her classmate 17 year-old Lexi Fotakos, junior at Sanford, watch the start of parts being made for a prosthetic hand in 3D printer.