Keeping a follower tracked to a cam profile is the classic headache of mechanical demonstrations. Ball bearings roll out of their grooves, wander off, and spoil the motion. The answer in this build is to use small magnetic spheres instead, set on the exterior groove of the mechanism, and they hold their position better than standard ball bearings do. That single choice is what makes the whole assembly read so cleanly.
There are two printed synchrotron assemblies in the project. The base plates come out grey with the cam tracks embedded in them, one track circular and the other a sinusoidal star pattern. The model was drawn in Autodesk Fusion and printed on a machine labeled Bambu Lab. Inside, slotted rotor discs drive internal magnet holders that measure 4 mm in diameter and 2 mm thick, each working with hidden internal magnets.
The operation is deliberately simple. The rotor is spun by hand, the radial slots push the magnets, and the magnets reciprocate radially as everything turns. Out on the rim, the spheres trace the cam profiles, following both the round track and the star. The whole thing is operated on a blue silicone workbench mat.
What is still open is the application. The maker suggests a multi-stage clock mechanism as a potential use, but the project stops at demonstrating the two assemblies. Whether the idea would hold up as an actual clock train is a question I would love to see explored.
Project by Proto G Engineering. Watch it on their YouTube channel: