mechanical marble clock moves steel balls into pixel-like digits to tell the time

Robotic arm picks up steel balls for mechanical marble clock

Youtube channel Strange Inventions creates a mechanical marble clock that automatically moves the small steel balls into pixel-like digits to tell the time. Moved one by one by a robotic arm every single minute, the automated device is roughly the size of a chopping board, so it can fit on the user’s desk. Almost the entire structure is 3D printed in polylactic acid, which is a plastic made from fermented plant starch, usually corn or sugarcane. 

While it’s not the toughest material since it can warp or can crack along layer lines, it’s suitable for a mechanical project like this, the mechanical marble clock, especially since it’s lightweight enough to be moved anywhere. The color choices here are also colorful – gray and white as the main body, with accents of red and yellow – so it is immediately seen and adds vibrant shades to any space it occupies.

all images courtesy of Strange Inventions (Jens Maker Adventures)

Clock that works through magnet attached to a servo

The inspiration for the mechanical marble clock comes from Ivan Miranda, an engineer known for building enormous marble clocks at an almost architectural scale. The response project is quite the opposite, though, because the creator tries to see what the smallest, simplest, cheapest version of this idea could work. The result is an automated machine with a small robotic arm, which moves the marbles and is built around hobby servo motors. The arm picks up the steel balls using a permanent magnet attached to a servo, combined with a cam system, which is a mechanical arrangement of shaped discs that converts rotation into a specific push-and-pull movement. 

When the magnet drops and touches a marble, it picks it up. Then, a small separator ring pushes it down to scrape the marble free. There’s no electromagnet or complex electronics needed. It’s just geometry. The numbers displayed on the clock use a 3×5 pixel font, dubbed the smallest readable digit format, with each marble acting as one lit pixel in the grid. When the time changes, the arm calculates exactly which marbles to move, where to take them from, and where to place them. The whole update takes about a minute to complete, which means the clock is always, in an obvious sense, always moving. Creator Jens from the channel Strange Inventions (Jens Maker Adventures) documents the making in a video, an overview on how the mechanical marble clock is made and works.

mechanical marble clock automatically moves the small steel balls into pixel-like digits to tell the time

the balls are moved one by one by a robotic arm every single minute

the automated device is roughly the size of a chopping board, so it can fit on the user’s desk

almost the entire structure is 3D printed in polylactic acid

detailed view of the tiny steel balls

project info:

name: This Marble Clock Fits on Your Desk

channel: Strange Inventions (Jens Maker Adventures) | @strange_inventions