Micro Sawppy Beta 3 Suspension Rocker (Single Piece)

My rover Micro Sawppy Beta 3 (MSB3)’s suspension bogie attaches to its rocker assembly. Just for the sake of experiment, I designed and printed a single-piece rover suspension rocker. Rovers MSB1 and MSB2 had a complex multi-piece rocker design because its many mounting points were not coplanar and I couldn’t figure out how to align everything along 3D printing layers for maximum strength.

I redesigned the steering servo and rotational bearing mounting mechanisms for MSB3. As a result, it was almost possible to get everything lined up. The lone exception was that the front corner was still not easily aligned with the rest, but it could be a long sloping shape that spreads its load across a large surface area of print layers. It still won’t be as strong as if everything were lined up on the same layer, but it should not be an immediate structural disaster. It will, however, require printing with supports and accepting the rough surface that results.

I could help hide this poor surface finish, by aligning the print so it is on the inner surface of the suspension member. It’s not out of sight, however, since the front corner wheel stick out the front and thus this surface is always visible.

Every 3D printing slicer handles supports slightly differently. This particular test piece was sliced with MatterControl on default PLA settings and auto-generated supports. The flat portions (near steering servo and joint) had a rough surface but at least that section separated cleanly. The angled section (between steering joint and rocker pivot bearing) was a mess. That section of support did not separate at all, the surface visible here is a combination of forcibly tearing plastic apart and cutting the remainder free with a blade. I would not call this a complete success. Nevertheless the result does appear structurally sound. I would be confident using it in a rover design as there’s enough surface area across the diagonal section to hold together well, except under gross abuse.

This experiment proved that a single-piece suspension rocker is feasible. Practical, even. But I was not content to leave it at that and built a multi-piece suspension rocker in an effort to improve rover portability.

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