3D-Printed Linear Actuator Powered by a Micro Servo

If you’re building a robot and want a part to rotate, you have many inexpensive options. Choices for linear actuators, however, are decidedly more limited. Michael Graham (AKA “Engineer Dog”) found this out when attempting to design a coffee cup drawing robot, but instead of accepting this limitation, he created an excellent option himself.

What he came up with is a rack and pinion system that uses a micro metal geared servo to rotate a large gear, pushing itself along a rack. Impressively, this little servo setup can produce enough linear force to lift a roughly .5kg weight. As shown in the video below, it can move fairly quickly over its 80mm of linear travel, or be controlled to push gently when needed.

The actuator is assembled via five “Plastite” screws, which form threads when inserted into the 3D-printed material, producing a reusable bond that doesn’t require an extra tapping operation. An interesting feature of this build is that while you might assume that it uses a continuous rotation servo, it’s actually set up to move using only the servo’s standard 180 degrees of rotation. This not only means you don’t have to modify or obtain a CR servo, but can also take advantage of its feedback function, letting you know the actuator’s exact position.