The Osprey Hand is a wrist-powered mechanical prosthetic that was built in Blender based on the low-poly interior and robust components of the original Raptor Hand, but now sporting an attractive fairing and a very durable and comfortable low-profile universal-fit bracer.
The Osprey is optimized for the use of heavy gauge nylon monofilament, which resists linear compression and generates little friction, so has excellent Bowden properties; the cables are pulled to provide flexion and pushed to provide extension. This device requires neither elastics nor springs nor any mechanical extension system.
Heavy gauge nylon monofilament is generally inexpensive, and available as landscapers' trimmer line, nylon or Bridge nylon 3d printer filament, and as deep sea fishing leader line. I suggest fishing line, since it is available in a variety of thicknesses. Running through joints, the monofilament doesn't abrade at all, so there's no "sawing" of printed plastic.
Elastic resistance is a major drawback to many assistive devices, because resistance reduces a device's grip strength. Furthermore, as an elastic-extended device approaches full actuation, resistance from elastics increases, so that it may be quite difficult for a user to grasp small objects. Also, most elastic materials degrade quickly. Designs which reduce or eliminate elastic resistance are a welcome development.
Pay particular attention to the new bill of materials. The Cyborg Beast, the original Raptor and the Raptor Reloaded hardware kits are not compatible with the Osprey. However, the Osprey does use the same hardware as the Gamma Raptor. Materials kits and tool kits should be available in the near future, so stay tuned.
In this version:
Pin-and-Proximal sets with varying tolerances ("A" is loosest; "D" is tightest) Make it easy to compensate for differences in print scale, extrusion settings, and thermal expansion. Learn about Peregrine's ABCD Key in the instructions document !
Palm v.2.1 The thumb has been rotated to better oppose the fingers. This affected the palm stencil, which was also updated.
Support material was removed from proximal phalanges. Let me know if you miss it. The hinge on the distals was bulked up, since it was a common point of failure under heavy lifting.
I added a new bracer/gauntlet. This fits the Osprey aesthetic better, and it has easier-to-remove support material. The old bracer will probably become part of the Gamma Raptor design.
Updated bracer and palm, and removed the old versions. Added 3/4" triglide buckle. Added proximal "key" to help determine which proximal tolerance best fits in the palm.
Update 2016-6-16 Instructions have improved a lot, so please have a look.
Replaced proximal and distal phalanges: improved mechanical performance.
Added a printable bracer stencil that will fit most clients just fine. After fitting, any overlapping leather can be trimmed if needed, but on most clients that won't be necessary.
Added sets of snap pins that are more compatible with PLA. The original pins were calculated for ABS, which is softer. So they were pretty difficult to insert in PLA builds. These PLA pins have longer tines that bend better.
Added D-Ring buckle. This is a good secure closure for the loose-weave nylon webbing.
Added pin tongs and a pin pusher, to help with the insertion and removal of snap pins.