messing with split flap displays

It’s funny how ideas you have can stall the instant you don’t know what something is called, then SUDDENLY you accidentally see some article or random tweet or something about the very thing you were interested in and it makes a spark that drives you to DO something… for me that name was “SPLIT FLAP DISPLAYS”… I had no idea what they were called (and hadn’t tried hard to find out really) but always thought. Yeah, those are cool.


Split flap, flip flap or Solari displays (after the Italian manufacturer) are those big old noisy electro-mechanical displays you used to get at big stations and airports until the late 90s. Many have now been replaced with LED displays. These old displays have a lovely aesthetic and make an amazing noise.

I would like to make one. I first started thinking about this when I saw “Listening Post” at the Science Museum a few years ago. It’s well worth a look. I got to see it on my own which was quite chilling in a way. Anyway it uses LED displays rather than split flaps but they have used the split flap noise and programmed the LEDs in a way which mimics these displays. I also have memories of the split flap display at Kings Cross, in the early 1990s I did a lot of rail travel through London to Portsmouth and other Navy stations around the country. It was really my first time travelling around alone in big cities and I remember being fairly bowled over by the display at Kings Cross.


There is a wealth of video and other information out their about these much loved boards. I was reminded about them when I saw this “from the forums” Ada Fruit blog post about a DIY version by Ada Fruit forum user “SonicalFlair” who made this interesting thank you video. Amazingly someone I already know fairly well has the top search result on Google for Split Flap Display with his numerous blog posts about them. Tom Lynch who is one of the founders of South London Makerspace and a fellow conspirator in the Maker Faire scene, his being the Elephant & Castle Mini Maker Faire seems to have a huge amount of information on them on his blog.

Anyway I thought I’d have a go at knocking a concept up on the laser cutter. I’ve used birch ply and polypropylene sheet for the flaps. I quickly knocked out some vinyl letters to give the idea. I need to tweak a load of things and actually drive the flap drum (that’s what I call it) around properly. On my concept it just friction of the axle driving it around. I’ll very likely use little steppers next. I’ll probably blog about it too.


In my video below you’ll be amused to hear I’m driving this by turning the axle and it’s gets stuck at H… it’s okay really it only goes up to M.

here is a picture of the drum inside it’s housing. The top bar on the box folds the top flap in place.



Should you care to do so you can down load my prototype (or concept as I call it) on thingiverse but it is very much a WORK IN PROGRESS! I hope to achieve more though the steppers I want from China might take a month apparently (and quite reasonably it is China after all).