When he lost his job at a local manufacturing facility, Andrew Milarcik did what many former students do, he went back to school. “I had previously completed my AAS Mechanical Engineering Technology degree and thought that would be fine, but the company I worked for got bought out by a foreign concern and they really didn’t understand my degree,” he said. “So, I took a year to finish my bachelor’s.”
As part of his coursework at Kent State University at Tuscarawas, Milarcik enrolled in Advanced Manufacturing, a class where he had to complete a project of his choice. His choice was unusual, a low cost, easily accessible 3D printable prosthetic hand. But first, he had to get approval from his professor.
“What intrigued me about this project is it has no electronic parts. No batteries, no motors, no electric wiring,” said his instructor, Paul Dykshoorn, the engineering technology department head. “It is a simple solution to a complicated problem: How to build a prosthetic hand that has a wide range of function, that can be 3D printed anywhere in the world and assembled for a low cost, with easily accessible materials.”
Milarcik explained that the development of many prosthetics is relying heavily on cybernetics, along with the use of many special materials and electrical work.
“And that’s great, but there are a huge number of people who don’t have access to those resources and materials or the abilities to learn some of those higher skills. This is for them,” he said.
Since there is quite a bit of open-sourced prosthetic hand designs on the Internet already, Milarcik decided to choose one of those to start with as a base. “No need to reinvent the wheel,” said Milarcik. “[Its] legally allowed so long as it’s for nonprofit.”
The design Milarcik chose was one that the joints were made entirely of a homemade rubber product produced by mixing silicone sealant and cornstarch.
“The design is very interesting,” said Dykshoorn. “It allowed for a degree of flexibility without the need for springs and hinges.”
The goal of the prosthetic hand was to have three functions: make a fist, grip a bottle or tool, and hold a pencil or pen. The concept used to achieve this was a dial that could be turned with the “good” hand to achieve the three hand poses. Using the springs and strings, the dial would be twisted to either a “grip” “fist” or “writing” setting. In order to create a place for the dial; however, the open source prosthetic hand had to be modified.
“I used an open source software package that allowed me to punch a hole in the design of the prosthetic hand to allow the circular dial to be inserted into the hand,” said Milarcik. Turning the dial would pull the strings which acted as “tendons” to close the fingers.
Milarcik said the prosthetic hand worked reasonably well, but there was room for improvement. The issue with holding the pen was that the plastic fingers were too slick, but with the addition of a type of coating on the fingertips, he felt the hand could hold a pen quite firmly. Also, if he were to redesign the hand, he felt individual levers to control the movement of each finger would enhance the functionality of the hand.
“As I was staring at the finished product last week, I thought why didn’t I put individual controls for each finger instead of a single dial?” said Milarcik. This would require placing the springs between the “tendons” and the lever and consequently a new design of the hand. But it would enable the hand to do much more than the three functions he had originally aimed at.
But on top of improvements to his design, Milarcik believes word needs to get out that these free open source designs of prosthetics are out there and that building a prosthetic is within reach of many people, even those in the underprivileged areas of the world. Milarcik also believes there is more work to be done in looking at the 3D printing of prosthetic feet or legs.
But that will have to wait, as he found new employment in his field and is still finishing his coursework toward his bachelor’s degree at Kent State Tuscarawas.
To learn more about the Kent State Tuscarawas engineering degree programs, visit: https://www.kent.edu/tusc/engtech