Robotic Arm – Simple Device (Compatible with 10 mm Diameter End Effector)

I. Design Inspiration

Inspired by the principle of parallel-jaw grippers, this design employs a pair of meshing gears to achieve synchronized opening and closing. It is specifically developed as an end-effector for small DIY robotic arms, featuring a rear sleeve that accommodates a 10 mm diameter connecting rod secured with M3 fine-thread screws, and compatible with SG90 servo motors. This makes it an ideal attachment for robotics courses and STEM‑based mobile robot projects.

II. 3D Printing Process

The main frame and gripper are printed using PLA filament, while PETG can be selected for the gears to enhance wear resistance. A 0.3 mm assembly clearance is left at the gear-meshing points, with all parts having a uniform wall thickness of 2 mm. The design avoids complex overhangs, requiring only minimal support structures on the small curved surfaces near the gripper tips.

III. Assembly and Functionality

The rear cylindrical section features a standard 10 mm mounting hole for direct insertion onto the robotic arm’s linkages. The servo motor is mounted in a side-mounted slot; a single servo drives a set of gears, enabling synchronized opening and closing of both gripper jaws. The arc-shaped gripper jaws are designed to accommodate various small objects.