3D Print Yourself A Split Flap Display

February 20, 2025 by Lewin Day 7 Comments

Split flap displays! They’re mechanical, clickety-clackity, and largely commercially irrelevant in our screen-obsessed age. That doesn’t mean you can’t have a ball making one of your own, though! [Morgan Manly] did just that, with tidy results.

An ESP32 C3 SuperMini serves as the boss of the operation, running the whole display. The display is designed to be modular, so you can daisy chain multiple characters together to spell longer words. Each module has 37 characters, so it can display the alphabet, numerals 0 to 9, and a blank. Each module contains a 28BYJ-48 stepper motor for controlling the flaps, and a ULN2003 driver board to run it and a PCF8575 IO expander to handle communciation. An A3144 hall effect sensor is also used for positional feedback to ensure the display always shows the right character. The flap mechanism itself is relatively straightforward—a drum with all 37 flaps is until the correct character is reached, with the blank flaps hosting a magnet to trigger the aforementioned hall effect sensor. The flaps themselves are 3D-printed, with filament changes used to color the characters against the background.

If you’ve ever dreamed of building a flap-display clock or ticker, you needn’t dream of finding the perfect vintage example. You can just build your own! The added bonus is that you can make it as big or as small as you like. We’ve seen some interesting variations on the split flap concept recently, too. If you’re cooking up your own kooky electromechanical displays, don’t hesitate to let us know!

Split-Flap Clock Makes A Nice Side Quest In Larger Project

February 7, 2025 by Dan Maloney 2 Comments

Sometimes projects spawn related projects that take on a life of their own. That’s OK, especially when the main project is large and complex, In that case, side-quest projects provide a deliverable that can help keep the momentum of the whole project going. The mojo must flow, after all.

That seems to be what’s going on with this beautiful split-flap clock build by [Erich Styger]. It’s part of a much larger effort which will eventually see 64 separate split-flap units chained together. This project has been going on for a while; we first featured it back in 2022 when it was more of a prototype. Each unit is scratch-built, using laser-cut fiberboard for parts like the spool and frame, thin PVC stock for the flip cards, and CNC-cut vinyl for the letters and numbers. Each unit is powered by its own stepper motor.

To turn four of these displays into a clock, [Erich] milled up a very nice enclosure from beech. From the outside it’s very clean and simple, almost like something from Ikea, but the inside face of the enclosure is quite complex. [Erich] had to mill a lot of nooks and crannies into the wood to provide mounting space and clearance for the split-flap mechanism, plus a thinned-down area at the top of each window to serve as a stop for the flaps. The four displays are controlled by a single controller board, which houses an NXP K22FN512 microcontroller along with four stepper drivers and interfaces for the Hall-effect sensors needed to home each display. There’s also an RS-485 interface that lets the controllers daisy-chain together, which is how the big 64-character display will be controlled.

We’re looking forward to that, but in the meantime, enjoy the soft but pleasant flappy goodness of the clock in the brief video below.

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Split-Flap Clock Flutters Its Way To Displaying Time Without Numbers

November 5, 2024 by Donald Papp 18 Comments

Here’s a design for a split-flap clock that doesn’t do it the usual way. Instead of the flaps showing numbers , Klapklok has a bit more in common with flip-dot displays.

It’s an art piece that uses custom-made split-flaps which flutter away to update the display as time passes. An array of vertically-mounted flaps creates a sort of low-res display, emulating an analog clock. These are no ordinary actuators, either. The visual contrast and cleanliness of the mechanism is fantastic, and the sound they make is less of a chatter and more of a whisper.

The sound the flaps create and the sight of the high-contrast flaps in motion are intended to be a relaxing and calming way to connect with the concept of time passing. There’s some interactivity built in as well, as the Klapklok also allows one to simply draw on it wirelessly with via a mobile phone.

Klapklok has a total of 69 elements which are all handmade. We imagine there was really no other way to get exactly what the designer had in mind; something many of us can relate to.

Split-flap mechanisms are wonderful for a number of reasons, and if you’re considering making your own be sure to check out this easy and modular DIY reference design before you go about re-inventing the wheel. On the other hand, if you do wish to get clever about actuators maybe check out this flexible PCB that is also its own actuator.

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Classic 1960s Flip Clock Gets NTP Makeover

March 26, 2023 by Robin Kearey 14 Comments

Many of the clocks we feature here on Hackaday are entirely built from scratch, or perhaps reuse an unusual display type. But sometimes, an old clock is just perfect as it is, and only needs a bit of an upgrade to help it fit into the modern world. One such example is the lovely 1960s Copal flip clock (in German, Google Translate link) that [Wolfgang Jung] has been working with — he managed to bring it squarely into the 21st century without changing its appearance one bit.

Like most flip clocks from the 60s and 70s, the Copal clock uses a small synchronous AC motor to advance the digits. Because this motor runs in step with the mains frequency, it also acts as the clock’s timing reference. However the original motor had died, and a direct replacement was impossible to find. So [Wolfgang] decided to replace it with a modern stepper motor. He designed a small PCB that fit the original housing, on which he placed a Trinamic TMC2225 stepper motor driver, a Wemos D1 Mini and a small 5 V power supply.

Thanks to its WiFi connection, the D1 can find out the correct time by contacting a Network Time Protocol (NTP) server. Displaying that time would be tricky with the original hardware though, because there is no indication of which numbers are displayed at any time. [Wolfgang] cleverly solved this problem by placing an IR proximity sensor near the lowest digit, allowing the D1 to count the number of digits that have flipped over and thereby deduce the current state of the display.

There’s plenty of fun to be had with classic flip clocks like this, and with a bit of hacking any old split-flap display should be usable for your own clock project. If none are available at your local thrift store or yard sales, you can always roll your own.

What’s The Time? It’s Casino’clock!

July 30, 2022 by Sven Gregori 6 Comments

As the saying goes, nothing can be said to be certain, except death, taxes, and the never-ending inventiveness of clock hacks. No matter how tried and proven a concept is, someone will always find a new twist for it. Case in point: notorious clock builder [Shinsaku Hiura] took the good old split-flap display approach, and mixed things up by using a deck of playing cards to actually represent the time.

Technically, the clock works just like a regular flip clock, except that only the upper half of the split-flap is used to display the digits, while the lower half is showing the cards’ backsides. Other than that, the mechanics are the same: a set of hinges holding the cards are arranged on a rotor that’s moved by a stepper motor until the correct digit is shown (STLs available on Thingiverse). Aces low, Jokers are zeroes, and the queen strikes at noon.

At the center of it is an ESP32 that controls each digit’s motor driver, and retrieves the time via WiFi, keeping the general component count conveniently low. Of course, one option is to arrange the cards in their order to keep rotations at a minimum, but let’s be real, the flapping sound is half the fun here. So instead, [Shinsaku Hiura] arranged the cards randomly and mapped it in the code accordingly. You can see it all in action, along with some additional design information, in the video after the break.

For some more of his clock creations, check out this different flip clock approach and the Hollow Clock. But if the future is of more interest to you than the present, here’s a matching Tarot deck.

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Split Flap Display Tells Us The Word

March 2, 2022 by Bryan Cockfield 12 Comments

LED and LCD displays are a technological marvel. They’ve brought the price of televisions and monitors down to unheard-of levels since the days of CRTs, but this upside arguably comes with an aesthetic cost. When everything is covered in bland computer screens, the world tends to look a lot more monotonous. Not so several decades ago when there were many sharply contrasting ways of displaying information. One example of this different time comes to us by way of this split-flap display that [Erich] has been recreating.

Split-flap displays work by printing letters or numbers on a series of flaps that are attached to a spindle with a stepper motor. Each step of the motor turns the display by one character. They can be noisy and do require a large amount of maintenance compared to modern displays, but have some advantages as well. [Erich]’s version is built out of new acrylic and MDF, and uses an Arduino as the control board. A 3D printer and CNC machine keep the tolerances tight enough for the display to work smoothly and also enable him to expand the display as needed since each character display is fairly modular.

Right now, [Erich]’s display has 20 characters on two different rows and definitely brings us back to the bygone era where displays of this style would have been prominent in airports and train stations. This display uses a lot of the basics from another split flap display that we featured a few years ago but has some improvements. And, if you’d prefer restorations of old displays rather than modern incarnations, we have you covered there as well.

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A Flip Clock That Flips Up, Not Down

November 24, 2021 by Dan Maloney 3 Comments

The venerable flip clock has become an outsized part of timekeeping culture that belies the simplicity of its mechanism. People collect and restore the electromechanical timepieces with devotion, and even seek to build new kinds of clocks based on split-flap displays. Designs differ, but they all have something in common in their use of gravity to open the leaves and display their numbers.

But what if you turned the flip clock on its head? That’s pretty much what [Shinsaku Hiura] accomplished with a flip clock that stands up the digits rather than flipping them down. The clock consists of three 3D-printed drums that are mounted on a common axle and linked together with gears and a Geneva drive. Each numeral is attached to a drum through a clever cam that makes sure it stands upright when it rotates to the top of the drum, and flops down cleanly as the drum advances. The video below makes the mechanism’s operation clear.

The build instructions helpfully note that “This clock is relatively difficult to make,” and given the extensive troubleshooting instructions offered, we can see how that would be so. It’s not the first time we’ve seen a mechanically challenging design from [Shinsaku Hiura]; this recent one-servo seven-segment display comes to mind.

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