Erich Styger's DIY Split-Flap Clock Expresses Time with Vintage Motion in a Modern Build
Four-digit clock displays 52 characters in a beech wood enclosure built and driven by an NXP Kinetis K22 microcontroller.
This DIY split-flap clock project from Erich Styger is a compact four-digit display showing the time, short words, and color indicators using hand-built split-flap characters made from PVC sheets and vinyl decals. Anyone with access to digital fabrication tools like a laser cutter, 3D printer, and CNC router can build this strikingly expressive clock.
In the past, we covered a larger 20-character split-flap sign from Styger. It used a similar microcontroller board to power the steppers that spin the flapping digits. One critical difference between the older project and this one is the four-character display limit. However, an improvement to the DIY split-flap clock is increasing the individual glyphs on the flaps from 40 to 52. Now, each digit on the clock can display the English alphabet, numbers, additional characters (.-äöüéèà), and color blocks. Styger's colors include red, blue, black, and yellow. Since the characters are CNC-cut vinyl decals, you could make the characters be any symbol!
Styger controls the custom-built flap letters with a tinyK22 controller and custom breakout board. The tinyK22 has an NXP K22FN512 microcontroller. The board, originally available through Lucerne University's Applied Sciences and Arts department, appears in previous Styger projects. The custom split-flap controller is a carrier board for the tinyK22 that contains an Analog Devices (formerly Maxim) DS3232 real-time-clock (RTC), 12V input, voltage regulators, headers for controlling the stepper motors, and serial interfaces. The tinyK22 supports UART and RS-485, which Styger uses to communicate with other Split-Flap controllers.
While Styger has utilized medium-density fiberboard (MDF) in past projects, the DIY split-lap clock's CNC-crafted external enclosure uses 18mm thick beech hardware. Internal components, such as the split-flap structure, use high-density fiberboard (HDF) for their construction. However, those parts are not visible. The combination of black-on-white digits surrounded by the lightly tanned beechwood results in a handsome and sturdy timepiece with a distinctive sound when operating.
Styger continues work on other, larger split-flap projects. However, this scaled-down iteration is small enough for anyone with the right tools to build. For more information, check out Styger's blog post.