PIPBot 2.1: Fully 3D Printed "Print-in-Place" Robot

There is a category of 3D printed models called "Print-in-Place," which allows a fully assembled, working machine to emerge directly from the print bed, ready to use and fully articulated. This technique enables complex interconnections that are only possible when parts are printed in close proximity—though not in contact—but interconnected and sometimes fully enclosed by adjacent parts, much like a 3D puzzle.

Perhaps one of the best examples of what is possible using print-in-place design is the PIPBot 2.1 at https://www.3dhonza.com/pipbot. The complexity of this design is truly amazing, and includes interlocking tank tread components, gears, and mount points for expansion.

I have included a video of my completed print job which required about 30 hours (if memory serves). It printed flawlessly on the Bambu X1E, but failed on the Prusa XL, much to my surprise. After completing about 25% of the print job, the smaller parts, not yet enclosed by the upper layers, detached from the print bed. I tried adding glue stick to the print bed (generally not required with PLA), but to no avail. After many attempts, the best I could achieve was to delay the detachment.

My current hypothesis is that there is something about the gcode that is causing the nozzle to scrub the current layer, eventually pushing the smaller tread elements off the print bed. Considering the massive number of polygons in this model, it is possible that the Prusa Slicer has any issue with this particular model. I will be sending the STL file to Prusa for additional testing, if this is indeed the issue.

Next Steps

My plan is to add servos and sensors to test the durability of the tank treads over a few hours of operation for localization. The components of the treads and the primary axle lack bearings, so the PLA where there is direct contact will likely wear over time. More to follow!