Talon Hand 3.0
by profbink, published
This is a remix of Makerbot's Snap Pin Robohand. Thanks go out to the designers of the "Complete Set of Mechanical Anatomically Driven Fingers", Ivan Owen of Mech Madness Designs http://mechmadnessdesigns.com/ ; Richard Van As of Robohand http://robohand.net/ ; Michael Curry, the designer of the Snap-Together Robohand ; and to all the collaborators at e-NABLE https://www.facebook.com/enableorganization
I've optimized the design to be more ergonomic/comfortable, and to use leather as an interface material. With 3 pieces of leather you can fit this prosthetic device to a person lacking fingers on one hand. This is a wrist-powered device, so the user needs a wrist to be able to actuate the fingers.
Version 3.0 includes many updates. Version 3.0 is not compatible with previous versions. I have removed the old files for several reasons, some of which I describe below.
The main change, and in my view the most important one, is that I'm doing away with the arm bars in favor of the Osprey-style low-profile bracer. The arm bars are two bars that run up the sides of the forearm. The arm bars and the cable anchor used to attach to the leather bracer via screws. But the whole notion is problematic.
The old configuration makes it difficult to estimate where the bars (and the anchor) should attach to the leather bracer. Another problem is that it doesn't accommodate different arm widths very well. And even when you can get a perfect fit, the arm bars violate a basic principle of prosthetic design. The "soft on hard, hard on soft" principle indicates that materials that touch the skin close to bones should be soft, and that hard materials should only be used on soft tissue, where it won't push against bones. The arm bars run right next to the ulna on one side and right next to the radius on the other. That is uncomfortable. But the hard plastic component of the Osprey bracer attaches to leather on a single, meaty surface on the back of the forearm, and soft material (leather with straps) surrounds the remainder of the forearm. Peregrine (my son and a user of both the Talon and the Osprey) has noticed an improvement in comfort, and I think that's why he prefers the Osprey now.
So with the 3.0 update, I'm pulling out the files for the arm bars and the cable anchors and replacing them with Osprey-type bracers. In fact, I replaced every component of the Talon Hand with updated versions.
Here's a clip of my son Peregrine putting on his Talon 2.2:
And here's he is playing at home:
After upgrading to 2.7, and some 2.0mm monofilament cables:
For more information or to get involved, visit http://enablingthefuture.org/
You can print everything with no support. I'd suggest adding a brim in print settings for the palm to control warping. Bed adhesion pads may be added to the palm in the future, especially if it is requested. Adhesion pads have already been added to the bracer.
Cable the fingers with heavy gauge nylon monofilament, which is available as fishing line or round trimmer/weed whacker line (like for landscaping) for the cables. This hand will open without elastics. The cables push and pull. The cables anchor in the bracer with set screws. Read and watch the instructions, and ask questions in the comments.
For Talon Hand version 3.0 and beyond, the Osprey/Gamma Raptor instructions are the most helpful, since the assembly process is very similar. The only difference is that you need a thin piece of leather for the "upper" of the Talon, whereas the dome-shaped palm of the Osprey takes foam. You should apply closed cell orthopedic foam to the underside of the Talon's cable guide to protect the user during heavy gripping. Here are instructions for the Osprey:
Outdated written instructions for previous Talon and Ody Hands are here.
Ivan Owen made a wonderful 3-part tutorial using the 2.0 version of the Talon. Many things have changed, but this is still a great video series for assembling this kind of device. Thanks Ivan!!
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Talon Hand 3.0 by profbink is licensed under the GNU - GPL license.
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