About

This is a small gripper for 180° micro servos, such as the TowerPro SG90. The gripper works by using a rack and pinion to move one of the gripper arms.

The gripper is easy to assemble and only requires one screw. The micro servo clips into the gripper. The gripper has screw holes for attaching it to other parts or surfaces.

Design

From a mechanical viewpoint a pinion and gear gripper has a few advantages over a lever or hinged gripper. It has fewer parts, is easier to assemble and it applies a constant force throughout its movement. Its disadvantage is that the gripper opening is smaller.

Parts

There are three parts to this project which need to be assembled together post printing. Only the spur gear requires a M2 screw to attach it to the micro servo.

• Pinion gear
• Gear rack
• Servo mount

The piton gear has 14 teeth and the gear rack has 11 teeth. Both have a pitch of 20° and teeth height of 2 mm.

Assembly

The micro servo need to be set to 180° before the servo is attached to the gripper. The rack should placed on the servo mount with the gripper arms in the closed position. Then clip the micro servo to the gripper.

Acknowledgements

• Gripper partially based on the design of Simple 3d printed 9g servo gripper by brunoip
• Servo holder partially based on Servo Halter mount SG90 klipps by Robokalle