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Welcome to my prosthetic hand page!

As an intern at AIO Robotics, I designed this prosthetic hand to assist those with limb differences so that they may grasp objects by simply curling their wrist. This hand is completely mechanical, requires no electronics, and is tendon-driven. While its functionality is not revolutionary, this project exploits the use of flexible filament to remove the need for pins at the joints, making it easier to scale the prosthetic based on screw sizes without having to worry too much about the tolerances of 3D printer extrusions. Additionally, I built the prosthetic to uphold a streamlined look, retaining the tendons in channels and underneath a forearm shell. The resulting product looks pretty awesome to me. While this prosthetic has not undergone live testing with a recipient, I have posted the details of the printing and assembly to Instructables for anyone interested in expanding the outreach of this project. I am completely expecting a flaw(s) in some form or fashion, so feel free to make modifications as you please! I am also very open to suggestions.

Before I get started, I would like to give a quick shout-out to AIO Robotics for giving me the incredible opportunity to intern at the company and providing that exciting start-up vibe. Check out AIO's printer, the Zeus--I have yet to come across a printer that is as high quality and dependable as it is (seriously). Their emphasis on software really pays off. While the Makerbots, XYZ, and Airwolf printers I've used in my club keep breaking down, the AIO keeps churning away excellent prints, and there are more features to come. Furthermore, I would also like to thank the Tampa-based Handling the Future Organization for giving me the ideas, advice, and vision for improvement. Its members played a huge role in the direction of this project. Without them, I would have never created this prosthetic.

With that, continue on and enjoy!

Step 1: Materials List

These are the materials that I used for the prosthetic that I printed. Feel free to find alternatives to these materials if they are more convenient and/or less expensive.

  • Seattle Sports 1/2" Bulk Foam with Adhesive, Grey
  • Jaybird and Mais 30/31 Adhesive Foam: 1/4" x 5" x 2 yards
  • https://shop3duniverse.com/collections/3d-printabl...(I chose these over the ones on Amazon because they are all clear colored, great for maintaining the clean aesthetic I wanted. Same price, too. Check them out!)
  • MagicShield 500M 100LB Super Dyneema Strong Braided Fishing Line
  • Screws (refer to "Scaling the Prosthetic" step)
    • All screws are the same thread as what is dictated on the scaling chart (i.e. the default prosthetic only uses 6-32 screws)
    • Screws for fastening the lower palm to the upper hand (length on scaling chart)
    • Screws for fastening buckle clips to the inner forearm (0.25" long for default prosthetic scaled by a factor of 1.00)
    • Screws for tensioner pins (1-1.25" long for default prosthetic scaled by a factor of 1.00)
    • To find approximate lengths of tensioner pin and buckle screws for other scaling factors, multiply the length by the scaling factor.
  • Dowel pins (size dictated on chart)
  • PLA filament
  • 1.75 mm flexible filament (i.e. Verbatim Primalloy, NinjaFlex, etc.)
  • Tools: 3D Printer, scissors, files, sandpaper, screwdriver, Allen keys, hot glue gun, super glue
  • Optional but very helpful tools: drill press/hand drill, soldering iron
<p>how much it would be in case of cost estimation</p>
<p>The cost relies upon whether you have the printer, PLA filament, flexible filament, and other standard supplies. If you do, the cost is $20 - $30, depending on whether you buy the screws and pins in bulk or individually. If you don't, it might be a little more pricey--flexible filament is somewhat expensive at around $50 per roll. Hope this helped!</p>
<p>Great design and intstuctable! I'm not quite clear on how the user manipulates it, could you please elaborate on the function of the tensioner pins?</p>
<p>Yeah, sure! Essentially, the prosthetic targets those who are missing fingers but have some wrist motion. Upon inserting their palm into the hand and bending their wrist, the &quot;tendons&quot; pull on the fingers, causing them to curl. The tensioner pin make sure one end of the tendon is fixed and can recede into the inner forearm to increase the tension of the string. I'll put up some more details in the intro talking about how it works once I have the time to.</p>
<p>very cool, thank you for your response</p>
<p>It&acute;s great! </p>
<p>It is impressive!. Thanks</p>
<p>I'm impressed. Excellent Instructable. Thanks.</p>
<p>Awesome work</p>
<p>That is a really nice looking prosthetic hand</p>

About This Instructable

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Bio: I'm a UCLA mechanical engineering student passionate about building super cool things ranging from rubber band guns to robotic arms! Hope you enjoy my ... More »
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