Summary

This is a chain of ball joints that are printed preassembled. It comes as an open chain or as a closed loop.

Print, and enjoy!

Instructions

The chain is made of ball joints that are printed pre-assembled. You will likely need to apply some force to break them free. The inner spheres are actually slightly deformed so that you can lock the joints in the chosen positions. If a joint does not lock, rotate it around the connector axis - it should become stiffer at some angles. Make sure your plate is properly leveled to avoid the outer and inner spheres to bond on the first layer: this happens if too much plastic is poured due to the plate being too close to the nozzle.

The provided 'csg' files can be imported with OpenSCAD and rendered into a stl - both contain 12 ball joints. The result is shown by the image rendered with transparency. This is a parametric model created with my own software. I will release the software soon (still working on it) but I include the script for reference - should be easy to convert to OpenSCAD.

Several assemblies are possible:

balljoint_chain.csg is an open chain
balljoint_cycle.csg is a closed loop

I provide stl files for the chain and loop of 8 joints (for some reason OpenSCAD has trouble with the 12 joints version on my computer). I also included gcode of the 12 joints version for my Replicator 1 -- use at your own risk (afaik the code may not work on a different printer).

I printed it in ABS, at 0.2mm layer thickness, 120 mm/s travel and 60 mm/sec print speed. These are the settings used in the provided gcode.

Have fun!

Preassembled ball-joint chain