Raptor Adaptor – A 3D Printed Hand For Wilhe

Before assembly

You must check the address before you ship!

Developing a hand for Wilhe at Rochester Institute of Technology

By Skip Meetze, e-NABLE Volunteer


“No, don’t call the Post Office” warned Brenda Schlageter, our shipping expert.  “It is not a good idea to try to get a postal or shipping service to change a package destination after it has shipped… especially if it is going out of the country.  The delivery service will then assume that someone is trying to steal the package (by having it shipped to their own address).  The item will end up in customs where it may spend the rest of eternity!”

The team who learned this lesson with me included Emily Sanservereno, Farrukh Mohiuddin, Eric Freeman, Jade Myers and Jon Schull, and our hearts sank when we learned that Wilhe’s prosthesis was headed for the wrong address.

It all started at the end of September, when several hundred people gathered at Johns Hopkins Medical Center to learn how  the e-NABLE community provides 3D-printed prosthetic hands for kids.  One couple made  the 4,000 km trip all the way from Colima Mexico to see if they could get a hand for their 6-year-old son, Wilhe, who was currently using a prosthetic arm with a harness that operated a pair of hooks for grasping things.

Before assembly

This type of prosthesis has been in use for more than 100 years, and it enables below-the-elbow amputees to open the hooks with a shrug of the shoulders while a heavy rubber band pulls them back together.   This enables the user to do most of the two-handed tasksthat everyone else takes for granted.

Standard trans-radial prosthesis copy
Wilhe had seen a video showing a child with one of the cool 3D-printed hands that e-NABLE was providing for kids all around the world, and he wondered if he could have one.  His parents brought his prosthetic arm to the Hopkins conference to find out.  They found that there were several research teams represented at the conference who were exploring the development of 3D-Printed arms, and they left Wilhe’s prosthesis with the Rochester Institute of Technology team to be used as a guide for making Wilhe an arm with a hand.

The RIT team was finishing the revision of an arm for a girl named Lusie at the conference.  It attached to her arm above the elbow and the fingers were actuated by a mechanism that pulled on strings when she moved her elbow.  The team had learned about some advantages in user comfort and control with harness-actuated devices, so students on the team began exploring designs that might work for Wilhe using his harness.  Eric and Jade began working on harness designs while Emily and Farrukh worked on adapting the arm.  Jon Schull had been working with the students on some harness concepts that used 3mm printing filament rather than woven straps to make a harness and I had designed some little tinker-toy-like fittings that could be created on the printer to hold the filament harness together.

RIT Arm and Lusie
After a month passed by, the team was worried about getting a good fit to Wilhe’s arm with him being too far away to cast a perfectly fitting cushion like they had done for Lusie  who came into the lab for a fitting. 

We were all concerned about so much time passing with Wilhe going around without his prosthesis!  During a discussion about options, Jon wondered if we could put a hand on Wilhe’s existing prosthesis.  I had developed a modular adaptor that let the standard Raptor hand work with the RIT arm, and we were planning to use that with Wilhe’s version of the arm, but no one wanted to take the risk of damaging Wilhe’s existing prosthesis.  I looked at the hook on the prosthesis and held it up next to the adaptor on a raptor hand and realized that the hook could actually fit inside the adaptor and hand!

 Having developed some proficiency with a free modeling software called Tinkercad, I set to work.  By Thanksgiving, we had a proof-of-concept model!  It worked without having to make any changes to Wilhe’s prosthesis, but it needed to be rugged enough to stand up to use by an active child and it needed to be repairable by Wilhe’s family if it broke.  Meanwhile, Wilhe’s dad was politely inquiring about our progress…

 The students helped me to keep the printers humming as we worked out the kinks in the design, and after making some documentation, we took the package to the campus post office on December 17. I posted the video describing how Wilhe’s family could repair the arm and how they could also return the prosthesis to it’s original configuration.  We shared the open-source design on YouMagine and on Tinkercad, so others could build on our ideas (although we recognize that Wilhe’s adaptor is custom made for his prosthesis and it will not fit other arms without modification).

 My proud email to Wilhe’s dad announcing our success got an immediate response… Oh No!  It was shipped to the wrong address!  We exchanged a few emails about what our options were, but it all boiled down to waiting … waiting… waiting… Until we had given up on Wilhe having a happy Christmas.

 But on Dec 23, we got the email announcing that the package had arrived!!!!

 Wilhe 5
Stay tuned!  There is more to come in the new year!

Coming soon


https://www.youtube.com/watch?v=91Pn5Bx2n6o&list=UUc8pda6kN0lr2oyegFkgdsQ   Skip”s youtube

enablingthefuture.org/videos-prosthetists-meets-printers-conference-2014/  Hopkins video page

https://www.youmagine.com/designs/wilhe-s-raptor-adaptor-terminal-device-for-existing-prosthesis  YouMagine Wilhe Adaptor design files

https://tinkercad.com/things/8rOq92c76jG-wilhes-adaptor-left-10-assembly tinkercad design files

https://www.youmagine.com/designs/the-raptor-adaptor-v1-0   Raptor adaptor Design files