My latest project is the “Time Weights” Clock.
As it sounds, the time is presented as the height of three moving weights representing the current time hours, minutes and seconds. The twist is that each of the weights are connected on one long continuous loop that is reeled in and spooled out on demand. The software determines the correct position of each of the weights based on the time and the geometry of the design, and turns each of the three stepper motors accordingly. It takes into account that each weight much also pass on the additional belt required by the more significant time element(s). Additional consideration is given to account for the difference in belt length around the stepper drive pulley and the weight pulley based on the vertical height of each weight.
An interesting mathematical problem to model and solve, indeed!
Here’s a (crappy) video showing the work in progress and the successfully operating spooling mechanism that was cobbled together from an old tape measure.
The video shows the spooling mechanism reeling in belt slack as the seconds weight crosses the minute boundary.
With help from Doug Commons, I designed and cut several sets of weight hangers on my CNC machine. These weight hangers connect to the belt pulley and allow for the attachment of the suspended plumb bob. In addition, a pocket hole is cut to allow the insertion of a rare-earth magnet that is part of the homing system that allows the clock to determine it’s “home” position. The parts have been cut in 1/4″ HDPE (High Density Polyethylene), 1/8″ acrylic, 1/4″ MDF and 1/4″ ply to try out different styles and to test different cutting techniques.
The hardware – still on the breadboard – consists of an Arduino Nano, a real-time clock, a 4×20 character LCD display and the three stepper motors driven by A4988 stepper motor driver modules.
Stay tuned and remember that time weights for no man!