A 3DOF miniature joint based o two 13x4x5 bearings and two 6x12x4.5 thrust bearings.

Model uses M4 bolts for axes, M3 and M2 assembly bolts for assembly and anisotropicity Z pinning.

There are bearing variants for 13.1 and 13.5 to compensate for eventual hole shrinking during printing.The inset expander piece goes into an armature tube and is fixed shut by screwing in the axis bolt, which also has a friction nut on that keeps the thrust bearings squeezed into the runner tracks.A generic attachment piece at the end of the joint, for fixening to something mobile.Two washers go inbetween the two parallel attach point bearings. A bearing between bearing and center piece should also help mechanival stability, for plastic material.

Low polygon model with full assembly also provided.Photos are of a slightly different version.

Notes:

If misscaled, scale up 1000% or down 10%.

The M4 hole in the central piece needs threading done by an M4 threading tool.The same for the two M3 holes joining the attachment pieces.

The expander piece should also be threaded, but only halfway, or 2/3rd way, so it doesn't lose it's expansion function. Screwing in the axis bolt should take some force for a good friction force setting in.

There are small support elements added to the expander piece since I had problems with the edge flicking up during printing and generally the roundness, which is important, gets deformed without them. File them off after printing.

All objects placed in the files the way they should be printed. This is the optimum placement for anisotropy reasons, and for maximum precision on the bearing runner tracks.