11 Replies Latest reply on May 14, 2017 9:54 PM by Jonathan Kuniholm

    Need help finding a blueprint for prosthetic arm

    André Santos

      Hello, im a student, im on my first semester of computer aided design and im using solidworks, i've looked all over the internet for some blueprints of prosthetic arms and its all very generic things, i need help finding something detailed with every little component and part.

      Im new to this, maybe i've been looking in the wrong places, can anyone suggest a website(s) for me to use to find the blueprint, or that knows where to find it.

      Thanks in advance for any help. 

        • Re: Need help finding a blueprint for prosthetic arm
          Paul Salvador

          imho,..that is a broad question.... there are so many,... types,..sizes, materials.. and functions for each individual needs,.. and ...over the hundreds of years... there could be thousands of versions?


          • Re: Need help finding a blueprint for prosthetic arm
            John Henderson

            Try these guys, and let us know what you think ?


            The e-NABLE community has developed a collection of different 3D-printable assistive devices that are free for download and fabrication by anybody who would like to learn more about the designs or fabricate a device for somebody in need.


            BUILD A HAND – Enabling The Future


            If that kind of thing interests you, please check out SolidWorks Students & Robots  - Somewhere to learn, play and hone your craft ?

            • Re: Need help finding a blueprint for prosthetic arm
              Jonathan Kuniholm

              Andre - the problem that you're having is not unrelated to the problem that we (I am an arm amputee) have in getting a good prosthetic arm in the first place. It's probably important for me to explain a few things: 1) The way in which prosthetic arms are attached to the body (suspension) is NOT generic, and is custom for each user, as residual limbs are even more variable than feet (and no one picks up a suitcase with a shoe). Unfortunately, while there are designs out there, the primarily 3d printable ones are uncomfortable to wear because they're plastic, despite customization, and the methods used to customize are crude and not likely to create a good fit. 2) The most used prosthetic arms are body powered rather than electronic or externally powered, and are unlikely to be what you were thinking of or looking for when you set out on this project. 3) The number of people who could use prosthetic arms (most don't) is so small that this "orphan market" is unlikely to generate substantial investment and/or sharing of truly useful or detailed designs. 4) The landscape is littered with efforts that claim or propose to be open, but fail to actually deliver on publishing their designs. 5) Because the good CAD programs (like Solidworks) are all closed and proprietary, there is no file standardization and sharing of the often large, binary, and not human readable files is cumbersome and don't lend themselves to open source repositories like github that host open source code. I've proposed a way that might work, and discussed some of the issues here (Another Open Hardware License... But is the future of viral open source hardware already here? | The Open Prosthetics Pr… ). As regards SW, I would be thrilled if Dassault would release a free version of their software that could only save models openly licensed in the cloud, forcing viral openness and encouraging design sharing. It would be a great way to encourage users and not cannibalize their for-profit business at all.


              All that said, there are some published designs out there for components like hooks and hands, and some complete arm designs out there if you look. Unfortunately, the only design that I've found appropriate for a transradial (forearm) amputee like me are, as you suggest, so crude, useless and likely uncomfortable and unsecure so as to make it not even worth trying. There's no wrist rotation of any kind, no Bowden cable operation of the hand, and the hand is opened and closed by bending the elbow, presenting obvious difficulties in use: The RIT Arm – Enabling The Future The eNable site, by the way, has other designs: BUILD A HAND – Enabling The Future Another is here: The Open Hand Project - Downloads  All of these, by the way, suffer from the same problems described earlier related to plastic suspension and weak materials that don't stand up to any real tasks of daily living.


              We welcome any contributions that you might make to prosthetic arms.

                • Re: Need help finding a blueprint for prosthetic arm
                  André Santos

                  Im taking a degree in orthopaedics, up to now( in my country, which is one of the few with a school that teaches orthopaedics in europe) everything was hand made in  orthopaedics, im in the first class to learn new methods such as cad,  and prosthetics is a big part of orthopaedics, so hopefully  there will be some changes and modernization in this field in the near future.

                  Thanks for the help

                    • Re: Need help finding a blueprint for prosthetic arm
                      Jonathan Kuniholm

                      I'm of mixed feelings about the interest in prosthetic arms, education and 3d printing. On the one hand, it's great to have some attention paid to a neglected area. On the other hand, breathless and non-rigorous publicity given all of the really hardly distinguishable efforts that are mostly focused on 3d printed hands of exactly the same design is discouraging. I'm aware of numerous trips to emerging economy clinics (Haiti, India, e.g.) that bring piles of 3d printed copies of these hands, where the recipients over and over tell the donors that these things are useless and not appropriate for real use, only to have the same thing happen again.


                      (EDIT: maybe best course of action is to model the Becker Lock Grip or Imperial. This is plenty hard modeling and would relieve you of a design project that you'd have to complete in the course of learning to model.)


                      If you want to do something truly useful, make an incremental improvement and modernize a great product that's been used for many years, I'd recommend this project:


                      Update of the Becker Mechanical "Lock Grip" or "Imperial" Hands:

                      The Becker Lock Grip is my favorite anthromorphic hand. The current owner is the inventor's grandson, and the hand are still being sold: http://www.beckermechanicalhand.com/

                      While I love the hand, it has some limitations, notably the wideness of the grip at full open, the fixed thumb position, rigidness of the palm, etc. I don't believe that the owner has any intention to update the design, and the patent expired so many years ago that there's no question of legal barriers to creating an updated version that preserved any of the features or workings of the original.

                      Here's the original patent: Artificial fingers and hand mechanism | The Open Prosthetics Project


                      Imperial Hand Inside Views: http://www.swisswuff.ch/tech/?p=934

                      Other posts about the Becker on Wolf's site: http://www.swisswuff.ch/tech/?cat=67


                      If you're interested, I can describe what I think might be reasonable design goals and a list of improvements, and we could create a project page on Open Prosthetics. In short, I think that someone could do a design for very low-run manufacturability that used COTS parts (try identifying tapered springs that would work for the fingers, e.g.), perhaps some 3d printing or prototype injection molding, and added features like a positionable (opposable) thumb that would open and close with the fingers. Note that this remains a voluntary opening device that would need to retain sufficient grip strength to be useful.


                      Anyway, as was pointed out before, even this is a real design project that is likely beyond the capabilities of a new CAD student, and further confabulates the somewhat conflicting goals of designing something new and simply learning to build a model of an existing product. Perhaps a still somewhat difficult goal but much easier than new product development would be to create a model of the Becker hand itself, as accurately as possible (and perhaps not including features such as the wood composite and deerhide cover of the original).


                      An additional point: obviously existing CAD models by others are NOT appropriate to include in your work in learning CAD, which should be entirely your own and represent something new, even if the new model is one you created of an existing and unmodeled device. Additionally, since you are posting this in May, I can't imagine that you have much time left to do a good job on this project.


                      Again best of luck, and I will try and help if I can.



                  • Re: Need help finding a blueprint for prosthetic arm
                    J. Mather

                    André Santos wrote:


                    Hello, im a student, im on my first semester of computer aided design and im using solidworks,

                    I think this project would be too advanced for a first semester CAD student.

                    Has your instructor approved this as your project.


                    I think someone with the skills adequately developed to take on this project would not have to ask for help.

                    I have seen a lot of examples by students trying to take on the challenge of designing a prosthetic that frankly, the results are rubbish.

                    I recommend you select an easier project. and consult with your instructor on the appropriateness of the selection.

                      • Re: Need help finding a blueprint for prosthetic arm
                        André Santos

                        Its complicated because im getting a new degree in something that mixes health and engineering, im in the first class ever ( in my country) to take it, ive had 3 semesters of pretty much med school, and then they told us se had to go to an engeneering school to take some classes, and cad is one of them, and they are expecting us to have the same preparation has people who had 3 semesters of engeneering and mechanical/eletrical design and things like that, but yeah my class is divided in groups each one with a a diffrent prosthetic, mines the arm, it was assigned by the teacher.

                        Im hoping that he ll be nice to us when evaluating the Project xD

                      • Re: Need help finding a blueprint for prosthetic arm
                        Roland Schwarz

                        I had it right here at my fingertips... seems to have slipped from my hand...