This Mechanical Clock Is Pure Marble Madness

There era of electromechanical enlightenment ended with the proliferation of digital computing, which made such absurd design challenges and expensive manufacturing unnecessary. Why bother with a complex mechanism when you can program a microcontroller to perform the same task? But there was an art to electromechanical devices that has largely been lost as a result. To revive that art, Ivan Miranda is building a spectacular mechanical clock that is pure marble madness.

This clock displays the time using marbles — but not in the way you're thinking. You likely read that and imagined something like an abacus, with the number of marbles indicating the time. Miranda's design is far more interesting than that, because it displays numeric characters like you'd see on a digital clock. Black marbles make up the background and white marbles act like lit "pixels." That looks very cool in a still picture and is absolutely mesmerizing to see in action.

The appeal of this clock comes down to the size and complexity of the electromechanical design. The marbles roll through an endless loop, forming numbers and then falling back down into a pile to wait for another ride. The machine selects the marble color it needs for each "pixel" in the grid, then sends it down the track. The marbles collect at a gate at the bottom to display the digits, then the process repeats.

But as far as the machine knows, the order of the marbles in the hopper-like collection is random. It picks up a row of marbles using a clever elevator contraption, but doesn't know what color they'll be. So an Arduino board uses infrared sensors to detect the color of each marble in the row. If the marble in a specific position matches the desired color, it gets to continue on its ride up the elevator. If it doesn't, a small solenoid pushes it off the elevator and back into the hopper area.

By checking every marble as it moves up the elevator, the Arduino is able to control the order of marbles rolling down the track. It might take a while, but eventually the correct marbles will end up in the correct row positions in the correct order.

That process isn't fast, so the track has two gates. The first gate collects the incoming marbles. Then, when the time rolls over to the next minute, it releases all of those so they continue down to the second gate and that is where they show the time. Just before the minute rollover, the second gate releases all of the marbles back into the hopper to make room for the incoming marbles from the first gate.

This is an insane way to display the time and the machine is gigantic, but it is incredible to watch. It would be perfect for an art museum or the lobby of a particularly hip corporation.