The Lucky Paw Prosthetic Hand

thingiverse

This a variant of the Robohand / Mech-en Hand designs that I've been working on for my daughter who was born with a moderate case of symbrachydactyly in her left hand that left her with only a functional and normal thumb The aim of this design is to create a tendon driven mechanical hand that allows the use of her thumb The design goals for this have been the following: Fingers with 2 joints Fingers offset with respect to one another (not all parallel) No elastics in the design, push-pull actuation Scalable and printable to a very small size along with hardware that allows for this Complete freedom of movement of the wrist - deviation as well as flexion and extension Adaptive grip, allowing the fingers to adapt to the shape of the object in the hand Printable on a typical FDM printer without the need for support structures Its still a work in progress, and the design has come along this far thanks to the amazing internet community called E-Nable. Come join us!! https://plus.google.com/communities/102497715636887179986 For more information and amazing stories:http://enablingthefuture.orghttps://www.facebook.com/enableorganization Instructions Included in the files are the STLs for printing as well as the Solidworks source files. Also included are a couple of assembly animations to show how the hand is put together The idea of this design is to have 2 independent parts (palm and anchor) sown onto a flexible fabric thats comfortable in the capacity of a glove - I havent finished testing this portion yet, so any input and ideas would be more than welcome...... Full Hand.STL has all the files laid out for printing To put the hand together you'll need dowel pins. The pins go through the joints with an interference fit in the holes on the outside and the inside joint has a loose fit around it allowing it to rotate freely There are 2 smaller pins in the intermediate and proximal joints that act as stops preventing the finger from overextending The fingers have been sized for the following 2 dowel pin sizes 3/32 x 5/8 inch, Qty = 4 per finger 1.5 x 10 mm, Qty = 2 per finger Once the fingers have been assembled, they slide into the palm. Its designed to be really tight, if you use a lubricant, they'll go in with some light tapping, otherwise some light sanding would be required before inserting the fingers Tendon: This hand is designed to use push pull actuation so strings that work with the other Robohand designs wont work here I've tried a bunch of different cables and I'm the most satisfied at the moment with Nickel Titanium Cables. Theyre incredibly flexible, kink resistant and work very well as push pull cables This company called Aquateko makes fishing leader cables with this material at very reasonable prices and they come in a large range of sizeshttp://www.aquateko.com/category_s/21.htm The cable would need to be crimped at one end so it doesnt slip thru the fingers. The fingertips have larger holes to accommodate a crimp Route a length of cable from the fingertip. When it gets to the palm, you'll need to pull the cable thru here, then bend it back again to route through the palm The Anchor is designed to hold an individual anchor per cable and a spring. This is to allow for an adaptive grip and allow wrist motion even after the fingers are closed The spring sizes that the anchor was designed for are Free Length: 1.375" Outer Diameter: 0.187" For the anchor, you can use one of the following 2 solutions E/Z Connectors: Can be found in any hobby storehttp://shop.dubro.com/p/heavy-duty-e-z-connector-qty-pkg-2/aircraft_e-z-connectors?pp=12 You dont need the snap washer or the stem at the bottom, route the cable through and tighten the screw at the length you desire The other option is a bolt, nut and washer Drill a hole in the middle of the bolt shank, just below the head Route the cable through and clamp down with the nut and washer