Hand

Given the torque and size constraints imposed by the wrist, the hand was designed to remain under 0.3 m in length while supporting the required grip force and structural loads. A through-bore slip ring configuration was implemented, allowing a keyed shaft to pass through the hand stem, enabling continuous rotation without increasing overall length and minimizing bending moments on the wrist.

Unlike Hand 1.0, the gripper assembly is fully modular and independently replaceable. The gripper can be removed and swapped without redesigning the hand stem, allowing future teams to integrate new end effectors while retaining the same wrist and slip ring interface. Additionally, the gripper fingers themselves are interchangeable, enabling rapid iteration and task-specific customization without modifying the core mechanism. This modular architecture separates the rotation, structure, and gripping subsystems, improving serviceability, adaptability, and long-term usability.

Structural and enclosure components were 3D printed in glass-fiber reinforced ABS using a Bambu P1S with a hardened steel nozzle, providing high stiffness and wear resistance. The 6061 aluminum slip ring housing tube was machined manually in the DIB machine shop, where I designed and used a custom radial marking jig to ensure accurate hole placement before cutting and drilling features by hand.

The gear and linkage components were water-jetted from 5052 aluminum in the MAE machine shop, then sandblasted and brushed to achieve a smooth, low-friction finish at bearing interfaces. The servo drive gears use stamped fine-pitch teeth to ensure proper meshing and torque transfer. This manufacturing approach combined precision machined metal load-bearing components with rapidly iterated printed structures, enabling a lightweight, modular, and serviceable gripper assembly.

The hand is assembled using M4 and M5 fasteners, with the slip ring housing secured by top and bottom aluminum caps featuring radial mounting screws for structural retention and service access. The gripper is built as a hybrid plastic–metal structure, with ABS-GF printed components providing mounting geometry and water-jetted aluminum linkages providing structural strength and load transfer.

All gripper joints pivot on M5 shoulder bolts with precision spacers (McMaster-Carr), ensuring proper alignment, low friction, and repeatable motion. The layered assembly approach separates structural load paths (metal) from mounting and enclosure features (plastic), improving rigidity, durability, and serviceability while allowing rapid iteration of the gripper mechanism.