Prepare to Be Mesmerized by Michael Klements' Mechanical 7-Segment Display

Michael Klements has “always been fascinated with flip displays, like the ones used in airports.” After seeing another project where someone had started creating a single-digit display with solenoids, he decided to build on this inspiration and make his own two-digit display with micro servos.

Klements’ contraption is controlled by an Arduino Mega in order to take advantage of its 15 PWM signals. This allows it to use 14 of these signals to flip the segments into place, rotating them into view as appropriate, then swinging to a less-visible 90-degree position when not on display. The technique is rather effective, owing in part to the bright green PLA that was used, and spray painted black on the back and sides to make it less visible when in the “off” position.

The design looks much simpler to implement than a traditional flip-dot clock, though as with any project there were a few challenges. Given the mechanical nature of how this clock works, Klements had to account for interference between the middle segment and two adjacent segments, programming them to flip out of the way to allow it to properly move. Also, the build seems a bit noisy, so a timepiece or other display made with this principle wouldn’t be appropriate in all situations.

Still, it’s a clever bit hacking, and more information along with its code is available in the Klements' write-up if you’d like to take a few of these ideas for yourself!