Hand

Given the torque and size constraints imposed by the wrist design, the hand had to remain under 0.3 meters in length. To achieve this while maintaining the desired leverage, I implemented a through-bore slip ring configuration. This allowed for an extended shaft length without increasing the overall hand length, reducing excess bending moments on the wrist. A single fastener secures the shaft to the wrist, enabling quick removal. The base features a hypoid bevel interface to work with the wrist Additionally, I reused legacy finger hardware and servos developed by previous Yonder teams to conserve resources and time given the quick turnaround.

The body is printed in black matte PLA and reinforced with 1/16" aluminum plates oriented perpendicular to the print layers, creating a strong quasi-composite structure. Plates were cut using a FabLight metal laser cutter. Heat-set inserts and press-fit brass bushings were installed at key locations, along with custom impressions for bearings and slip ring components. A milled ¼" slit in the .5" shaft allows slip ring wiring to route cleanly through the dead axle, enabling infinite rotation without entanglement. 

Assembly uses standard M3 and M5 fasteners, 0.5” ID bearings, brass bushings, and M3 heat-set inserts for mounting. The aluminum plates sandwich the main PLA body, with one plate removable carrying the servo and the other remaining static. Fingers are mounted via 10 mm bearings and spin freely, each featuring non-slip gripping pads.