V.2 Flex Fingers, Swivel Thumb Prosthetic Hand

SummaryThis is the latest version of a work-in-progress prosthetic hand that incorporates flexible fingers, adaptive grip, flexible gauntlet, mesh palm and rotating thumb. The fingers, palm mesh and gauntlet are designed to be printed in flexible filament only. The filament used in the photos is TPU. You can size the fingers by scaling them before slicing. The photo shows a 125% gauntlet, a 120% palm with two 110% fingers, two 115% fingers, one 120% finger arranged in an approximation of an actual hand. The mesh palm is scaled the same percentage as the palm or can be printed larger for a bigger pocket.Print SettingsRafts: NoSupports: YesResolution: .3Infill: VariedNotes: The revised .stl files now utilize a ball joint attached finger/thumb. The fingers have been enlarged at the base, tapered to the tip and also incorporate a textured bottom for better gripping ability. Silicone "tippies" will also aid with grasping objects. The ovals are now mildly compressible to better conform to odd shapes. The thumb is made to swivel in its socket so that it can either oppose the palm or align somewhat parallel and still function according to user needs. The photo is outdated....

Palm is PLA with 30% infill printed at 200C with support touching the build plate. The fingers are printed on their side in TPU at 230C with 17% infill and support from the build plate. The gauntlet is printed on end with brim for stabiliity in TPU, 30% infill at 230C. The whipple tree, tensioner pins and wrist connectors are all printed in PLA. To eliminate "angel hair" from TPU ooze I used a heat gun. Flame also works but is neither as effective nor clean as the heat gun method.Post-PrintingAssemblyThe fingers print whole and snap into the palm with no further assembly except running a line from the fingertip through the palm to the whipple tree behind the palm. The whipple is then connected to the gauntlet. The thumb is a direct line from finger to gauntlet through the palm. Monofilament works best for actuation purposes. I used 50# monofilament for the fingers and 80# monfilament for the thumb. Also, I think that crimps work best for tying off the various lines. You can use either one line per two fingers (looping around one of the whipple sides for each pair, then the finger ends can be crimped) or individual lines crimped at the whipple. Fingertip crimps will fit inside the finger structure for safety. Care needs to be taken when adjusting the thumb in relation to the palm so that all fingers can fully close and re-open cleanly.How I Designed ThisCredit to:Vladimir for his Gauntlet and whipple designs and profbink for his "Osprey Hand"