Maker Ivan Miranda is no stranger to turning ordinary glass marbles into reliable timekeepers. His latest machine abandons fixed digits entirely. Instead of showing hours and minutes, a massive circular wheel slowly rotates while black and white marbles form continuous scrolling text around its outer edge.
The structure is almost entirely 3D printed. A large piece of black plastic forms a circumferential ring that fits on top of some steel ball bearings, allowing it to turn smoothly. A stepper motor arrives and spins the entire wheel in exact small increments, which is excellent because another device inside the ring also requires precision.
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It’s also powered by a stepper, and its task is to select the appropriate colored marble for wherever the wheel is. As the wheel rotates, the selector arm aligns with each succeeding slot and drops a black or white marble into place, resulting in a color sequence that travels around the outside of the wheel.
Marbles that fall off the bottom are captured and fed back up to the selector, allowing the item to continue functioning without requiring a constant supply of new marbles. IR sensors monitor the colors of the marbles as they pass by, and while early versions of those sensors found the workshop illumination to be a little too dim to work correctly, they were able to resolve the issue and the readings became constant.
However, the finished machine still requires some human guidance to get it started in the correct location, and if the black and white marbles are not balanced correctly, the letters can become a little crooked, with gaps in the lettering. Despite this, the text remains visible, and the display has no predetermined length.
The finished wheel is quite large, filling the workshop, despite the fact that it is essentially a collection of printed plastic components fastened together. Many redesigns were required to bring the channels, selector arms, and marbles back into a single, stable system, and the end result is a mechanical display that can, in theory, scroll along any message you choose as long as the marbles are circulating.
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