Unknown Domain

Shopping List

The following is a shopping list of items that I am currently planning to use for the split-flap control module controller PCB, it will be responsible for controlling the stepper, sensing it’s current position and receiving commands.

  • 1x MCU (Atmel ATTiny85)
    738-0681 – £1.42
  • 1x Stepper Driver (Allegro A3967)
    680-1797 – £2.80
  • 1x RS485 Line Driver (MAX1483)
    540-3000 – £2.47
  • 2x Reflectance Sensor (Kodenshi SG2BC) – Untested as yet
    455-0975 – £0.64
  • 2x RJ45 Socket (TE Connectivity 0-215877-1)
    290-0414 – £0.97
  • 1x 3 Way 2 Row Header Pin (RS)
    251-8137 – £0.15
  • 1x Disk Drive Power Connector (Molex 15-24-4441)
    670-4256 – £0.50
  • 1x Black Cat5e 0.5m Patch Cord (RS)
    557-026 – £0.72
  • 2x 4 Way Connector (TE 171825-4)
    718-8532 – £0.28
  • 2x 4 Way Housing (TE 171822-4)
    680-1219 – £0.23
  • 16x Crimp Pins (TE 170205-1)
    712-1602 – £0.10

External interest

It’s a funny thing that everytime I blog I get one or two people emailing for help, is it that blogging makes Google rate me higher and there are just vast swathes of people looking for someone making these split-flaps or simply coincidence, perhaps I am a fashion leader (who am I kidding?).

Anyways two companies are expressing interest in my work, neither sound like paid jobs but I guess if their experties can help me make my project a reality that would be cool…

I won’t name them this time but one is an another agency who want a reception centre piece, the other is an agency wanting to use it for an exciting client project. The latter project sounds more like it’s going somewhere as they have an actual budget for it and sound like they have experience making other cool projects too!

I am hopeful that my work might finally lead somewhere. What I often wonder is how I am going to make money in this field of work, I would love to do projects like this full time but with the benefit of an electronics engineer to speed up the projects.

If you wish to employ me please email me and that would be awesome.

Screen printing

I am not one for analog printing processes or indeed digital ones, come to think of it I am not one for print processes at all. But making this split-flap display requires a good chunk of knowledge in this area, as the flaps need to be printed onto and the traditional process has been to use screen printing with oil-based inks.

I am very luck to be in a position where I can easily do screen printing with professional facilities, free of charge, however they don’t really allow the use of oil based inks, which are apparently a dying art, primarily because of genuine health and safety concerns in the fumes associated with them and their related cleaning, thinning and retarding chemicals. Oil based inks work best because they are hard wearing and permeate into plastic like polypropylene better.

Trip to the printers!

On Tuesday I went to use the above facilities to do some tests with the kind help of a colleague who runs the facilities called Liz Wilson. She mixed up a bunch of potion inks using her screen printing mojo, and our first ink was to the following recipe:

  • 1/3rd Aqua Art Mix (white)
  • 1 Tbsp. System 3 Textile (glue/binder ? not sure)
  • 1 Tbsp. System 3 White Acrylic Ink

Liz’s special mix

This potion worked very poorly unfortunately, it was too think and so stuck to the screen leaving a horrible mess as you can see on the right. Also you will note it scratches very easily and is not opaque enough to look really white.

Liz’s special mix + 3 tbsp. opaque binder

Undisparaged we pressed on and then added 3 tbsp of binder to the mix, and then mixed it in with what was on the screen creating a probably about a 1.5 tbsp mix of binder. The results were again not great, but certainly looked better. At this stage we went for a new idea, we decided to use normal inks but try heat curing them, this is tricky as the melting point of PP is only 150ºC and the ideal curing temperature was some 280ºC!

50/50 acrylic / textile binder?

The first mix was a 50/50 between System 3 white acrylic ink and System 3 textile glue/binder stuff. This was much more opaque and seemed to be better instantly, we tried a high temprature cure without putting the heat press onto the plastic and nothing much happened, instead we dropped the temprature to a boiling 100ºC and used silicone release paper to stop it sticking, the results were good and the flaps were quite resistant to scratching too. I did a few test strips on real flaps to see if the heat press would smoosh the flaps out and cause them to become bigger, this didn’t happen however to get the scratch resistant finish desired I had to put it in for more than 90 seconds and they began to warp:

Scratch testing the 50/50 mix under various heat press durations at 100ºC

The final result of the tests with Liz were that I wasn’t happy with water based screen printing and the oil seems off the books for now, I had spoken to a chap called Chris Ratcliffe who advised using Apollo Inks or Screen Colours but it is all getting confusing and I think I need more help from Liz and others than I can really ask of them right now.

I am going back to my old system for now which is using vinyl stickers cut using a craft robo cnc cutter. The next thing is to get the beast back up and running as it’s been abused by students for 2 years and needs new blades and more no doubt!
UPDATE: Just remember that Liz suggested using Fujifilm Sericol Polydyne YD inks which I would have to buy, again like the others I don’t feel confident using them right now so I will hold off on screen printing as it’s just one more problem on the list of things in this project.

Split-flap Display – Prototype V3

At last, with the help from some friends I have built the long awaited third prototype of my project. The following details some of the design changes:


I decided to go with laser cut plastic gears like last time because the only decent range of timing belts and pulleys comes from McMaster-Carr and they don’t really offer a range of metric sized parts, which is a pain, there seems to be a real lack of mechanical power transmission parts. I am going to try contacting the 3D printer community about this as the gears are always super loose.

That aside the plastic gears work okay for now, and were designed using Matthias Wendel‘s Gear Template Generator software I still want to use pulleys but I need to find a better supplier that has the range I need. Why can’t I be an expert electronics engineer, mechanical engineer, computer programmer and designer all in one?


The housing was constructed of a thinner 2mm clear Perspex, last time I used 3mm, one disadvantage is that 2mm seems to shatter easily when dropped, also coloured Perspex isn’t readily available in 2mm thickness. It is also scary to cut in the laser cutter as you can see small pockets of fire under your work which are usually hidden by the opacity of the coloured material. I bought it from Hamar Acrylic, London and used a fantastic and cheap product they recommended for gluing called Plastic Weld, it’s basically a solvent that melts the edges, bonds them and evaporates leaving the two surfaces welded but no residue.o2


The idea for the catch came from a friend who suggested inserting a sheet of rubber rather than plastic that hangs down from the top giving it a ridged flexibility that allow the flaps to push against the catch until it flaps by without putting pressure on the sprockets.

The new design is dramatically bigger, by volume probably 100-150% larger! Next up I need to work on screen printing the flaps and the electronics I was working on before, having some trouble with inverted UART to RS485 signals, anyway here it is:



In an effort to remove my dependency on WordPress Multisite I am consolidating all my sub blogs from uni into this blog, they can be found as categories.

Learning Objective-C

The first programming language I ever learn’t to write, was ASP (not ASP.net) I had learnt a bit about HTML and was confused by CSS and JavaScript, but I wanted to experiment with including headers and footers, and with the idea of a user login system. I am quite sure the first try was diabolical, it I didn’t learn about password hashing until I learn’t PHP so there is no way that the passwords were hashed and I am not sure that I even used a database.

My days of IIS and ASP are long gone, I never use a PC these days and I don’t remember anything about ASP other than <% document.write(“Hello, World!”); %> (I think?). At some point I switched to PHP and like most new PHP programmers started writing and rewriting a CMS. Time passed, and my knowlege has improved, I now know bits and pieces of: PHP, C, JavaScript, and Java.

I bought my first Mac over the phone with my dad when I was at college in about 2004. It was a 14″ iBook with a Mighty Mouse, AppleCare Protection Plan and a AirPort Express base station. I don’t remember when I first got interested in learning to program the Mac but it wasn’t long after. I bought a copy of Aaron Hillegass’s infamously brilliant “Cocoa Programming for Mac OS X” (2nd Edition) book and got started. I didn’t know C then and hadn’t really understood Object Oriented programming either. The book was an extremely hard learning curve and even with my dad’s help I didn’t make it through.

Time passed and I tried again but got stuck again and failed, time passed and I bought the latest edition (3) of Aaron’s book and tried again, got further and understood more but still got stuck. A lot of time passed and I had been tinkering with little experiment projects all along, but it wasn’t until this summer that I knew I would have time. I bought a bunch of books in preparation for the summer:

That’s a lot of book, probably about 2,000 pages of book, but I am really commited this time, I have already completed the first book (Objective-C Programming) and really feel a lot more confident having learn’t it. I also think that the time coupled with previous attempts and reading other things has helped me to whizz through that book in about 24 hours worth of reading.

I am now on chapter 5 of the next book (Cocoa Programming for Mac OS X) and things are making more sense than I remember previous attempts did. I am hopeful that I can complete this book in the next week and a half to two weeks max and start playing about with some of the APIs, sadly the More Cocoa Programming for Mac OS X book isn’t out yet so my Amazon order is still pending, according to Safari Books it isn’t going to be published until October, so that is rather unfortunate. Aaron, fancy sending me a preview?

Either way I think I will hold off the Advanced book as it goes into networking and tasking which I think might be pushing it, and besides there’s tons of WWDC videos from Apple’s Developer channel to watch and I want to spend time on my Split-flap project, and a friend has come up with an idea for using flip-dots to make a QR code clock so we are going to try to make a flip dot, and we’ve ordered some samples from a polish company called Alfa Zeta.

Another email

Today I got an email I guess triggered by my last post pushing me up the Google-o-meter again? Perhaps co-incidence, each time I blog it seems to result in someone else emailing me?!?

This time more of a q&a email from someone like minded looking for help, I assure you I will be returning to my efforts this summer!

Hi there,

I came across your blog recently searching for info on Solari stuff. I’m doing a project here (New Zealand) with the Auckland City Council to install a split-flap system like this… hopefully? They’re keen and there’s some money involved but I haven’t heard anything back from Solari yet so have still been looking at other alternatives. Mine needs text, I’m planning to commission a writer to develop a speculative history about an actual train station here. It’s a very small station, but has a lot of historical baggage…

Anyway, wondering where you got to with your efforts? Did you ever get something made? Did you make it yourself? The info on your blog’s really useful, esp the link to Rebecca Baumann’s work.

Thought it was worth getting in touch,


Luke Wood

Signal to Noise by @lab_au

In an article by Filip (CreativeApplications.net) he writes about a project called Signal to Noise by LAb[au] which makes use of reclaimed and refurblished split-flap units from a station in Bruges.

A wonderful project, and as usual I have emailed them to let them know how much I love them, and if they know where I can get one, I so wish the UK Railways hadn’t destroyed theirs, I’d love to have a real one!

Perhaps this summer I will achieve this!?


IDEA: Google Image Search

I have an idea for a project where a whole room in a house / space is filled with products found by using the Google Image search’s visually similar option, I searched for this image:

And got all these interesting responses…

Google Search

Sketchup split-flap display

I thought it would be good to spend some time getting to know Google Sketchup, especially after watching Matthias Wandel’s amazingly clear video introductions on YouTube, it really helped a beginner like me move to the next level in understanding. Anyway, I made the following model of the original version one split-flap display because its simple but mainly because I still have the design, while the version two was made on the fly and I did keep the files on a purple USB stick I can’t find any more, if you see it, send me a shout!