[Harrison Low] published some 3D-printed linear actuators, which generated a lot of interest. He got a lot of advice from people on the Internet, and he took it to heart. The result: an improved version that you can see in the video below.
The original design used carbon fiber and Kevlar and was quite stiff. The actuators could move very fast, which was important to [Harrison]. However, they were also prone to wear and had issues with the force required to assemble them. He also wanted the design to be more modular to facilitate repair. The new design removes the bowden tubes, and the resulting actuator is both easier to assemble and easier to service.
One of the great things about 3D printing is you can iterate quickly, incorporating lessons you learn into new revisions. The old actuator, for example, failed after 39,000 cycles. The new ones were able to make 50,000 cycles and didn’t seem to be worse for the wear.
[Harrison] is looking at some future improvements, including using the motor body as one of the spools and switching to synchromesh cable. He’s looking for suggestions for the next generation, so be sure to share your ideas and experience.
If you want to make your own, the last part of the video shows detailed assembly instructions. It looks like they would be worth watching as the assembly isn’t trivial.