I made two marble automata this month, based on a popular scrollsaw project design.
I learned a great deal making the first one because there were design challenges in miniature that weren’t obvious. Tolerances of a few thousands of inches made the difference between marbles going up the run on the pistons, or not. Consequently, so did the size of the “marbles”. V1 uses small glass “no hole” beads; V2 uses #12 snake shot.
Here’s a video of the machines working.
For V2, I improved the V1 design, but I also tried an S-curved return ramp. I naively thought I could use the Shakeoko to make that ramp. Well, not so fast, Kemosabe. The ramp design required using two different bits and this reminded me that the Shapeoko doesn’t retain alignment during bit changes - at least not with the tolerance that I needed.
I resorted to routing just the internal channel with the Shapeoko. With a lot of hand shaping, and then cutting with a jeweler’s saw, I got a ramp that I could use. And in all fairness, I don’t think I could have routed the channel by hand. Ain’t CNC great?