Today we assembled the first full prototype of Chris’s arm! We are currently working through a few adjustments to the design and will assemble an updated version tomorrow evening.
The biggest change we made recently is modifying the design of the socket. Now the inside of the socket is open, with elastic bands stretching across to hold the upper arm in place. Additional elastic bands attach the top of the socket to the shoulder harness, to transfer some of the load to the shoulders and back. On the socket we bring next weekend, we will sew the elastic on rather than pinning it.
The end of the socket is connected to the forearm by screws, and the forearm is connected to the gripper thumb hand with a bolt. We also tried to create a natural angle between the upper and lower parts of the arm, because we hope to keep this device as inconspicuous as possible once we print it in a skin-toned filament.
We are using strips of Dycem, a non-slip material, to enhance the gripping capability of the hand. This weekend, we will bring two versions of the terminal hand with and without the Dycem lining to test whether this modification is useful.
Over the next four days, we will assemble the updated version of the arm, print extra sockets and terminal hands, and further prepare for the trip. We will touch down in Milot in just FIVE days!!