Cathy's Lucky Fin V3

thingiverse

<h2>Outline</h2> <ul> <li> This prosthetic hand model has no elastics for finger return (Push Pull / Bowden principle)</li> <li> Outside of the tendon cables, anchor and the screw for the tensioner, everything is 3D printed</li> <li> Once printed and assembled, the idea is to use leather straps to fasten the prosthetic to the hand - Refer to pics and video</li> <li> Remixed from a previous design, this is a revision to a model that I’ve been working on for my daughter</li> <li> Main design goals have been to create a prosthetic that allows full freedom of movement of the wrist (Radial/Ulnar deviation - side to side movement in addition to flexion/extension) and to eliminate elastics, thereby increasing the grip strength and making it easier for younger children to use</li> <li> The differences in this version with respect to the previous design are that the intermediate and distal phalanges are connected with dowel pin instead of the click into place the previous version had and secondly, the gimbal has been eliminated - In this version the wrist itself serves as the gimbal mechanism</li> <li> Video of my daughter strapping on the printed hand - https://www.youtube.com/watch?v=Quz7sEd8jfc</li> </ul> <h2> Specifics of this design </h2> <ul> <li> The intermediate and distal phalanges are connected with dowel pins. The idea is to use pla filament as the dowel pins (PLA+ is strong enough for this purpose) Currently sized to fit 1.75 PLA filament for a hand scaled to 86%, so you'll need to resize the holes depending on the size you need</li> <li> Another inclusion in this design are "tattoos" - The palm and proximal and intermediate phalanges have tattoo designs incorporated in them. Both tattoo and without tattoo versions of these parts have been uploaded</li> <li> The other experiment here is to see if the elimination of the gimbal makes for a more comfortable design - My daughter has a fully funtioning wrist so the idea is for her wrist to serve as the gimbal mechanism</li> <li> All other details of the design remain the same, so please refer to the descriptions in the previous versions for additional details. Parts from previous designs like fingers etc are fully interchangeable in case you prefer the click in place design the previous version had</li> <li> Also included are the mirrored Right Hand version of the palm - everything else should be the same</li> <li> All STLs and Solidworks design files have been uploaded</li> </ul> <h2> Assembly</h2> <ul> <li> The proximal phalanges have slots to slide the pins - align, push and they click into place on the palm</li> <li> The intermediate and distal phalanges are sized to use PLA filament (1.75mm) as dowel pins, interference fit on the outside joints and free movement on the inside. Size currently is considering a scale down to 86% that my daughter needs, so resize the holes according to the scale you require</li> </ul> <h2> Printing</h2> <ul> <li> The parts print well in the orientation as loaded in Thingiverse, printing straight up gives a very nice finish to the parts and requires minimal post processing</li> <li> Parts to be printed with supports – Intermediate and Proximal Phalanges, Palm</li> <li> Parts to be printed without supports - Distal phalanges (solid portion), Flexible pieces in distal and proximal phalanges (with flexible filament if using this option), Fingertips mould, Gauntlet and Tensioner</li> <li> I used PLA+, printed with 0.15 resolution, 25% infill and 2 shells</li> </ul>