Super-small Robotic Joints Don’t Exist? They Do Now!

[Tim] needed very small, motorized joints for a robot. Unable to find anything to fit the bill, he designed his own tiny, robotic joints. Not only are these articulated and motorized, they are designed to be independent – each containing their own driver and microcontroller.

6mm geared motor next to LEGO [Source: Pololu]
None of the photos or video really give a good sense of just how small [Tim]’s design is. The motor (purple in the 3D render above, and pictured to the left) is a sub-micro planetary geared motor with a D shaped shaft. It is 6mm in diameter and 19mm long. One of these motors is almost entirely encapsulated within the screw it drives (green), forming a type of worm gear. As the motor turns the screw, a threaded ring moves up or down – which in turn moves the articulated shaft attached to the joint. A video is embedded below that shows the joint in action.

[Tim] originally tried 3D printing the pieces on his Lulzbot but it wasn’t up to the task. He’s currently using a Form 2 with white resin, which is able to make the tiny pieces just the way he needs them.

[Tim]’s quiet about what the robot these joints is for will be like, but he did reveal that he foresees it using “lots” of these joints, so he’s been spending some time planning the wiring and communications as well as refining the design. We’re very curious about how it will all turn out.

People roll their own robotic joints and appendages when they have specific needs that can’t be met by current offerings, and the prevalence of 3D printing has made this process far more accessible than it has ever been before. For example, take a look at this unusual looking robotic appendage designed by [Kris] back in 2010; it’s worth a look just for how incredibly intricate it is.


11 thoughts on “Super-small Robotic Joints Don’t Exist? They Do Now!

    1. You can also get similar motors for just a few dollars on eBay. In my testing they are very similar unless you’re working near the limits. You can visually tell where Pololu has directed a higher quality product, but you have to be willing to pay for that too.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.