My sister’s latest project is a figure sitting in a rotating bowl, stirring something in a bowl with the bowl the figure sits in turn orbiting on a platform. And just for good measure, the figure’s head goes up and down and there are orbiting lights around the whole thing. Due to the nested motions implementing this presents a challenge, which is met by things called slip rings, which allow wires to make it through rotating joints. The motions are all relatively low speed, and for this kind of thing you’d normally use gear motors. Unfortunately, gear motors tend to be noisy and that ruins the effect. So I ended up switching to using stepper motors. This involves more wiring, but fortunately small slip rings with 12 wires are available (on Amazon of course) at a reasonable cost.
The video below shows the outer bowl orbiting on its platform. There will be surround around the turntable hiding the mechanism.
The video below shows the man stirring and the bowl rotating. Depending on if they counter-rotate or not, the effective speed of the stirring changes. This video was taken using the gear drive motors so you can get a feel for how noisy they are.
The stepper motors have been retrofitted, but because of the complexity of stepper motor drive, running it with them requires a pretty much fully developed control system due to having to run everything through the slip rings.
More to come.
