My sister’s latest project is a man standing with an umbrella over his head, with rain pouring on him from the umbrella. Her first idea was to use real water, but I persuaded her this was a bad idea for multiple reasons (clogs, algae, mess, the list goes on). So, she came up with the concept of using wires painted with a black and white spiral. When these rotate, it should look like stuff coming down. There are thirty of these all needing to rotate. The sculpture is only about 12 inches across, so there is not a lot of space. So, I came up with a drive concept that involves using belt driven pulleys.
The base plate is 3D printed on a fused filament printer and the pulleys, which need remarkable precision, are printed on a resin printer. A pair of miniature ball bearings supports each pulley. The belts are made from NinjaFlex 3D printing filament. It works well for a while, but then it starts ticking. I think for some reason the pulley shafts are loosening up in the bearings and shifting as they revolve causing a tick. I am currently redoing it using O-rings between the pulley shafts and bearings, which will make the pulleys less sensitive to shaft size and provide a damper.
