While we’ve reported on e-NABLE countless times, with the latest being their new e-NABLE Community Foundation, as well as ongoing activities like assisting parents in taking on the 3D printing of their children’s prosthetic hands and preparations for their latest conference, the one thing we don’t hear much about is elbows. Right? Lots of 3D printed hands, and a smattering of 3D printed arm prosthetics, but we haven’t heard of anyone tackling that complex, three-boned, hinged joint in terms of a prosthetic. One has been created though–which came about indirectly through e-NABLE.
Jesse McCabe recently became part of a project to help a boy in need of an elbow. He’d had some experience working with a 3D printed hand that works with muscle sensors and was interested in delving further into the area of both robotics and 3D printed prosthetics (see video below).
“The idea came when I was following an E-nable thread on Facebook,” McCabe told 3DPrint.com. “A woman was asking the moderator if anyone had developed anything to aide someone who did not have an elbow and therefore [had] a way to actuate most typical 3D-printed mobility aiding devices.”
McCabe’s earlier work
In corresponding with the mother, McCabe found out that young Daniel had a bilateral condition, but that she hoped he could start with a 3D printed prosthetic for the left side first. The goal, as McCabe began virtually from scratch for a 3D printed prosthetic, was to see that Daniel would have ‘command control’ of his elbow, with mobility in the hand as well.
“I used Inventor Fusion for Mac to design the concept taking inspiration from Robotica on Thingiverse as the joints are grown ball-and-socket with no support structure and function with little to no post processing,” McCabe told 3DPrint.com.
Tackling both the fit and scale for a preliminary design, McCabe was curious to see if the NinjaFlex inner liner would work for Daniel in terms of comfort. That would allow for it to be inserted into the hard upper component via Velcro. He plans to integrate a servo gearbox, weighing a mere five ounces, into the design for the elbow allowing for mobility and 180 degrees of motion and axial twist, thanks to the ball-and-socket mechanism.
So far, he has created three hands and sent one fully assembled, leaving Daniel and his mother to assemble the other three. He has made:
- Two elbows
- One forearm
- One NinjaFlex inner upper sleeve
- Two outer upper sleeves
- Wrist pins
- Spare metatarsals
McCabe’s eventual vision for the total design is for the user to be able to wear something similar to a fanny pack, bearing a battery with the servo controller. With this complete system, he would be able to employ multiple muscle sensors and 3D printed parts for maximum mobility.
Because he does not want to see this project incurring any expenses for Daniel’s family, McCabe is thinking about launching a crowdsourcing campaign for the actuators and sensors. His first version of the prosthetic was created on a Solidoodle 3, with the next produced on a CTC Creator Dual.
What are your thoughts on this design? Have you worked on any projects for 3D printed prosthetics, or do you know anyone who uses one? Discuss in the 3D Printed Elbow & Upper Arm Prosthetic forum thread over at 3DPB.com.
