Tool-less Corner Steering Motor Cover for JPL Open Source Rover

While building a JPL Open Source Rover, I would put the rover chassis in many different orientations in order to better access whichever part I was working on at the time. I’ve experienced recurring problems with the default corner steering motor cover popping off under sideways load, which happens when I have the rover on its side or on its back. The motors themselves are relatively robust but the wiring terminals at the end are fragile and difficult to repair if broken off. So I’d like to keep them protected as I work on other parts of the rover. I know I’m prone to accidental bumps that, thanks to Murphy’s Law, tend to impact the fragile and difficult to repair parts of my project.

Thus the motivation for this quick 3D printing project: an alternate design for steering motor covers. I had the following project goals:

  • Easy to print, without overhangs that would require support.
  • Tool-less installation and removal
  • Robust against sideways forces
  • Round shape to reduce chance of catching on obstacles.

In order to take advantage of nature of 3D printed parts, it was broken up into two pieces. The inner clip is printed at an orientation suited to clip onto the Actobotics aluminum rail without worrying about layer separation. The cap is printed at an orientation that makes it easy to print without supports. Separating the cap from the clip also makes it easy to create variants on the cap without worrying about compromising the Actobotics clipping capability.

With these caps installed on my corner steering motors, I was able to work in various orientations without worry of the cap falling off. I could also move the rover about and, thanks to the round surface, the cap is unlikely to catch on things and fall off. So even if a rover ultimately has plans for other caps, the round cap is still useful to have installed during construction and maintenance.

I’ve released this design on the JPL rover builder’s forum, hoping others would find it useful to build upon. The original CAD is a public document in Onshape, the read-to-print STLs have been uploaded to Thingiverse, and a video walkthrough explaining how it works has been posted to YouTube.

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