So, after a successful evening roll around the Homebrew Robotics Club meeting, I was starting to drive the rover(Which, in the spirit of other rover names, I've decided to name "Tenacity"), towards the door, when it skidded to a halt.

Yup, I broke another steering shaft.

What you see here is NylonX at 100% infill snapped clean off during a  turn, but not one it hadn't done earlier that night or day.  These parts can clearly support Tenacity's weight at rest, and even in motion, but they deflect and eventually break with use. So far, all the 3D-printed shafts, other than the shorter ones for the wheel/motor pods, have failed.

 If we look at the Sawppy Parts List, and in particular,  the 8mm shaft stock docs, we see that the drive shafts are spec'ed to 50mm long and the others are 60-84mm long. So, 50mm by 8mm is some sort of strain limit  for 3D-printed nylon parts, even if they're stiffened with carbon fiber.  The other thing worth pointing out here is that each of the failed parts is getting shear forces either vertically or horizontally. The steering shafts sit vertically, attaching the steering motor pod to the steering servo. The rocker-bogie shafts mount horizontally. So this isn't purely a matter of not being able to bear the weight of one whole side of the robot. Nylon does best when used to make parts with significant bulk, for lack of a better term.

So, where to go from here ?
I have a spool of PC(Polycarbonate) and, of course, the STLs for all the related parts, so I'm thinking about giving that a go. I also have some 8mm steel rod and access to a drill-press again, so I could go the Poor man's lathe route. Right now, just to get the 'bot back on it feet again, I think this is the best, quickest, route to take.

Unless, of course, Matterhackers wants to sponsor Tenacity a set of shafts with their new metal filament and sintering service. What do you think guys ? (Baby) Rover needs a new set of shafts(shoes) !

If you're not breaking things, you're not making things!