Unknown Domain

Twitter Display V2

Unfortunately almost all the files about this model were lost however it featured 3mm thick clear acrylic, with gears which were made using the Adobe Illustrator star tool and then capping the ends with the circle tool to make them less sharp and wearing.

I do have some images from the train back from the laser cutter and they used the same flaps as the original. The biggest improvement was the use of a stepper motor (from RS), connected via a ULN2003A to an Arduino and the accuracy despite the rush job was near 100%.

I do however have some images from the files I used to plan in, the first of which is an image showing (to scale) the stepper on the right, with a gear attached to its shaft, and connected to two more gears, providing clearance of the flap even at full extension.

This image shows how the gears and the stepper relate, and the flaps at the front at full extension (left).

The side panel where the gears were kept was originally designed to be two sheets of 3mm acrylic with a 5mm piece in the middle and 3mm gears such that the middle piece was to be cut with these three circles to make a space for the gears to sit in whilst holding them in a confined space to prevent too much wobble, in the end it ended up being a complete void to avoid any problems and reduce material count.

I think this is from version one but it ended up in version two's design files, it shows how the flap attaches into the sprocket wheels and shows a not to scale axel in the middle.

This final piece was used to measure the cap between the outer edge of the stepper hosing and the centre of the sprocket wheel axel, not sure why, presumably at the time I know how much clearance was needed to ensure the flaps didn't hit the motor and cause a jam.

With this design I also tried using Plasticard material which is styrene sheet material however the little legs snapped off from heat stress in about 1 second, while the polypropylene sheets didn't snap off unless forced or after 2 weeks of use, one in my degree show (v1) and one in the emerge graduate showcase (v2) where it died.

Twitter Display V1

The following is almost all the details you would need to manufacture the original display, including the original files, these are licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License, however I would suggest not building this except if you realise it won't work as anything more than an ornament, the accuracy of a servo motor is not suitable.

Speaking of servo motors it was supplied by Maplin, and was a generic model however it was hacked for continuous rotation. I used an Arduino Diecimila to run the motor for a random period of time and stop to make it look like it might if it worked.

The following is the vector PDF of the file used to cut the main structure on the laser cutter, the material used is 5mm acrylic from a supplier called Plastic Online, there is an error in the design which meant the servo mounting plate was useless and I replaced the square with the round hole for the axel.

The following is the vector PDF of the file used to cut the flaps on the laser cutter, the material used is polypropylene from a supplier called Sea White of Brighton.

The following is the vector PDF of the files cut on the Craft Robo which made the vinyl appliqués, materials from this site: MDP Supplies

More images of the unit in progress and after, and in action...

More4 Rebrand

In the past couple of weeks More4 did a rebrand and one of my favourite studios (Jason Bruges Studio) were involved. I cannot help but see the resemblance to Rebecca Baumann's work however the technique is the only real similarity. Although the technique in this case is my interest.

A great making of video, disappointingly little technical info but great video none the less.

Rebecca Baumann

Rebecca first contacted me in October 2010 looking for some help manufacturing 500-1000 split flap display modules however like me she had contacted Solari and they had been too pricey and she also asked about reclaimed units in the UK as she also had no luck in Berlin.

We spoke a little but nothing came of it, I just emailed her for an update but looked at her website and found she used another approach only recently, she used flip clocks and replaced the existing flaps with custom coloured ones.

She has produced two versions, Monochrome (blue) and Colour Field and it is something to beholden to.

It's interesting to see that a recent project by Jason Bruges Studio is very similar, either inspired by or working with Rebecca.


Emails from various people

Having had the Twitter Display v1 photos on my portfolio and being that Google is spartan of any useful results several people have contacted me over the years regarding my display, looking for help making their own, to name a few:

Two companies were interested in it for a office ornament...

  • RG/A
    Zoltan Csaki contacted me about something for the London office.
  • IDEO (Randy Plemel)
    Contacted me asking about something for the Chicago office.
  • Rebbecca Baumann
    Contacted me asking for help / advise on building a unit for her art project.
  • Media Lab Toronto
    Patrick Dinnen contacted me to get help working on his own Split-Flap project which I suppose is still in the works as there is nothing on his website about it.

I originally got in touch with someone at Network Rail (Tom Chaffin) about their old units back in 2009 but even then there was nothing about, too late I guess, however he did have some photos for me but I can't find them any more, he did have a interesting little bit of information about the recent history of the units within the UK rail industry:

The split-flap indicators where widely used for customer information systems on the railway, but the final installations have now gone on National Rail – the last I was aware of was the large main departure board at Liverpool Street and some small displays in the ticket office at Lewis; I forget the exact date, but I think Liverpool Street has been replaced by LED panels for over a year now.  I know for sure that there are none left in service as the Network Rail maintenance standard to maintain them has now been withdrawn – the standard no longer has any use.


The majority of the flap indicators where supplied by an Italian company, Solari SPA and as such these indicators were often called ‘Solaris’ by railwaymen in much the same way as vacuum cleaners are called ‘Hoovers’ whomever the manufacturer is.  However, some flaps indicators were also supplied from a company, I think German, called Krone.


The newest indicators consisted of a number of modules, each module having 80 flaps – each module therefore being able to display 80 different sets of information, though inevitably there would be at least one blank in that set of 80.  Earlier modules had just 40 flaps.  The flaps were printed both sides with sets of information – this varied from a set of a group of stations split over the two flap sides to final destination split over two flap sides – i.e. the two together would show “Victoria” or similar.  The flap spindle was driven by stepper motors with electrical contacts or I think in some cases optical sensors being used to ascertain the position of the spindle and hence stop the motor once the module was displaying the correct thing.  One of the major disadvantages of flap displays was that every time the timetable changed altering train service calling points or final destinations changed or even for a train company name/branding change, new flaps had to be silk-screen printed and then inserted into the indicators ideally the night of the timetable change.  The new main departure boards such as those at Liverpool Street, Victoria and Charing Cross had the columns of flap modules pivoted top and bottom, so to change the flaps it was possible to turn the column through 180 degrees and change the flaps from the inside.  With older displays a tower or ladder was required to work from the outside.      The displays were built up of a number of modules, from typically just two for a single-sided platform next train indicator to many rows and columns of modules for a large departure board at major terminal station.  We never used flaps where one module was used for individual letters – hence this problem with having to change the flaps when the stations changed would not exist, albeit with the drawback of a far more complex and expensive display required, but airports did (and may even still do somewhere) have displays formed in this way.


One of the great advantages of flap indicators, which other alternatives have not fully addressed, though they are now getting close, is their readability under all lighting conditions and viewing angles.  There disadvantages was the need to change flaps, as above and the ongoing maintenance cost for something which is electro-mechanical.

Solari Udine

Way back in 2009 I spoke with a chap called Riccado at Solari Udine who gave me a approximate quote for them to build my project... €40,000!!!

However he was kind enough to provide a PDF diagram which was interesting, and a photograph of that particular unit in production which as it turns out was installed in an American University Library to show some of the Google search strings of students in the library (filtered of course).

He also provided a word document of how the display was controlled which was based on a PC running a small web server application which acts as the interface, like any modern web API really.

Salient Information Systems

I thought it was a long shot but late last year I contacted Salient who I had seen sold Split-Flap displays way back in 2009 and funnily enough the site hasn't changed since then, however they basically said:

We are unable to help with this product type in such a small quantity. The setup and production costs for this obsolete technology is enormous and requires a sizable quantity to make it worthwhile. Think Airport or Railway station fitout size project.


Public Private Art Install

By far the closest to a complete project, a fabricated display and control system was a project by Martín Bonadeo, which featured 7 characters


Video of the installation:

Setup of the installation:

Quote from Martín Bonadeo's website...

A 7 characters split-flap-type device (such as those used in airports and train terminals in the 70) is located at Telefonica Foundation's main entrance. Each of these modules contains 30 characters including the letters of the alphabet and some punctuation. The board has a total size of about 30 cm. x 7 cm. high. All characters are moved every 1 minutes to stay fixed in a new letter. Only the first and last module will not move but remain always in the same positions, the letter "P" and "O" respectively. The rest of the characters is constantly forming the words "publico" (public) or "privado" (private). This sign is shot and this image is projected from one of the windows to the sidewalk of the Plaza Vicente López (next to the fence). This image has a size of 5 meters wide x 1 m high. The characteristic sound of this technology produced by the board is also amplified and "projected" to the plaza.


More on how this works:


History of the Solari Board

This is a snippet of a video I captured when it was on the BBC iPlayer back in 2009 to save it before it gets lost for ever.

Selection of other videos for curiosity