Picture of T-hook: prosthetic design for 3D printing

Build a printable version of the Trautman Hook, an out-of production prosthetic device. 

This is derived from work by the  the Open Prosthetic Project. Here is the description from their webpage:

The Open Prosthetics Project is producing useful innovations in the field of prosthetics and freely sharing the designs. This project is an open source collaboration between users, designers and funders with the goal of making our creations available for anyone to use and build upon. Our hope is to use this and our complementary sites to create a core group of “lead users,” and to speed up and amplify the impact of their innovations in the industry.

This instructable will start with some information on their design, then we will make modifications to create a version that can be built using low cost 3D printing technology. 

Hopefully, we will end up with a robust working model that can be easily reproduced.  I probably won't get there with just this instructable, but I hope that this will be useful to others with the same goal.

I should note that I don't represent any of these groups.  I also make alot of mistakes.

This is entirely built on the work of the open source community, including:

Replicator G


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Step 1: Collect resources

  There has already been alot of work done by the Open Prosthetics group.  It is documented here.  

Open Prosthetics as already done design and prototyping work.  I am just building off their work in a way that seems compatable with the MakerBot 3D printing equipment.

Bre Prettis at Makerbot pointed me towards this project, he posted STL files here:

Availble resources include:
Previus work (drawings, photos) -
    (they have also posted their design files, but I can't seem to open them)
STL files   -
Patents    -  id=Asx5AAAAEBAJ&printsec=drawing&zoom=4#v=onepage&q&f=false

Step 2: Equipment and Software

Picture of Equipment and Software


Replicator G
kelseymh4 years ago
As I look at this, it seems more of a proof-of-principle rather than a fully functional T-hook.  The material used by most 3D printers wouldn't be strong enough to deploy on a Trautman, I think.  Am I right about this, or is there something I've missed?
marc.cryan (author)  kelseymh4 years ago
it seems more of a proof-of-principle rather than a fully functional T-hook

You are correct. As of 4-11-10 I do not have a functional device.  This instructable is focused on the design process using open source software and low-cost open source hardware.

RepRap and Makerbot use a filimanet of melted plastic to build up parts.  This makes a pretty good part, but I haven't tested the stength myself.

If I get more done, I will add it to this instructable.


Could this be used to make a mold instead?  Perhaps then cast something more durable? I know a lot of people have experimented with casting aluminum, right?
Could the sufficient strength be achieved if a 3D-printed honeycomb core was wrapped with glass fiber mats and brushed with some resin? It would probably be easier to manufacture a single copy this way instead of making a complete mold for casting.
marc.cryan (author)  bullschmidt4 years ago
Could this be used to make a mold instead? 

Probably  - but the real goal is a direct-to-manufacture part.   Something that can be designed, printed, and used in about an hour.

I have little experience with prosthetics, so I can't really say if this would be useful, but it seems worth a try.

Interesting question!  How does cast aluminum compare in strength to a machined part?
Asking the wrong guy!  I just connected the two without knowing much about either! 
Okay, thanks.  I still think it is a tremendous project!  There are 3D printers that use sintered metal (I saw a cool one at the Maker Faire a couple of years ago), so this technique is potentially practical for deployed prostheses.
dscott43 years ago
I would love to see it added to the 3D print group I have just started

lemonie4 years ago
You might want to say how this is designed to be used, it's not immediately obvious.

marc.cryan (author)  lemonie4 years ago
Agreed - I am not really sure myself.  I have been working from only images and files.  What I've made so far is not functional.

Here is an image of a similair device in use:

I think it's probably important to the project to learn how the device is to be used, and reference other models in production. You wouldn't want to succeed only to find people telling you there's something better on the market. Why is this design out of production?

kelseymh4 years ago
Sweet!  I have added your I'ble to the OPP and AT groups.