The Mark VI Fin Gripper - Black Ram Hand. This hand was designed to use the The Fin Ray Effect giving the wearer the ability to pick up soft or odd shaped items not able to be grasped by rigid claws or fingers.
Each Fin Grip finger must be printed with a flexible material (I have used Ninja Flex for this one). I am not able to print flexible filaments on my printer so I used 3D Hubs to order the parts. The filament should be between 60-80 Shore A hardness (85 Duro shown which was still a bit stiff).
The hand is mechanically wrist powered and requires that the wearer have enough palm to push against the device. It converts the rotation of the wrist into a linear sliding motion to activate the end gripper. When the wrist is bent down the slider pulls back, closing the hand. When the wrist is straightened the slider pushes forward and the hand opens.
As can be seen the fingers flex around the object and then hold the part. There is a 2 finger "pincer" version and a 3 finger "Tri-claw" version.
14 x Bolts
10 x Nuts
3 x Fingrips - Print in Flexible filament or resin (60-80 Duro - Shore A)
3 x Hinges
1 each of the remaining parts.
If the fit of the parts is tight, lightly sand back the parts with a file.
The Black Ram Hand was designed not to be a replacement for current prosthetic hands, but to be an assistive technology tool/platform for allowing someone to design and use their own specific manipulators for individual tasks specific to that person. This is in the same way that Robotic grippers and end-effectors are designed for a specific goal. The Black Ram Hand is designed to help those with missing fingers or conditions such as Dupuytren's Contracture.
Hand in action