Robotic Gripper – Gear-Rack Pushrod Version

I. Inspiration

This design employs a composite transmission system combining a gear-rack mechanism with a connecting-rod pushrod, compatible with the SG90 micro servo motor. It is specifically engineered as an end-effector for small robotic arms, offering both a clear demonstration of the gear-rack transmission principle and practical functionality for grasping tasks in science-and‑technology‑oriented robotics.

II. 3D Printing Requirements

The main frame, gripper jaws, and pushrod are printed using PLA filament, while the gear-rack assembly is made from PETG to enhance wear resistance. A 0.3 mm meshing clearance is left between gear teeth, and a 0.1 mm fitting allowance is provided at hinge holes. The overall structure avoids large overhangs, minimizing the need for extensive support material during printing.

III. Structure and Assembly

The micro servo motor drives a pinion that moves a rack back and forth in a straight line. Two connecting rods synchronously pull the gripper jaws, enabling parallel opening and closing. The servo’s built-in locking compartment eliminates the need for additional fixation, and a standard mounting hole is reserved at the rear, ensuring stable gripping motion and compatibility with various small components.