Open source “split-flap” mechanical display
github.com
github.com
- Smarter Every Day https://www.youtube.com/channel/UC6107grRI4m0o2-emgoDnAA
- Tom Scott https://www.youtube.com/user/enyay
- Practical Engineering https://www.youtube.com/user/gradyhillhouse
Luckily he only posts new videos every few weeks. ;) And almost every one of them is time well spent.
Stuff Made Here: https://www.youtube.com/channel/UCj1VqrHhDte54oLgPG4xpuQ
https://theluxurytraveller.com/2019/03/review-qantas-first-c...
The only two I could think of are:
- they don't emit light, so maybe there could be some kind of light-sensitive situation where this would be required (though in that case e-ink would surely surpass it).
- the sound passively-alerting those present to updates. It's not obtrusive or attention-getting like a bell or spoken announcement, so only those wishing to notice the updates can listen for the sound, while others can go about their business unperturbed.
Anyone know of, or could imagine any others?
I could just about imagine a genuine use case in some kind of hostile environment. You could probably make one of these very resistant to water/temperature/radiation, with the controller kept safely out of the way.
(And agree with the nostalgia - I'm sure for many the sound is associated with a quiet anticipation or excitement of embarking on a journey.)
After a flap has passed the upper lip, which is kind of holding it back to have a precise "flipping point", gravity will take care of moving it down.
No gravity, no flap. ;-)
Add rotary springs (is this a valid term?) to the flap hinges so they're forced down once released from the top edge of the frame.
In any case they probably won't work upside down.
And dangerously out of date in airports and train stations.
When they break down they had to be covered to prevent misleading passengers.
- assuming a fixed output selection, a split-flap display can also achieve far greater visual quality than other competitors like flip-dot displays
- defective units can be automatically detected (by comparing the position of the indicator magnet), whereas stuck pixels in flip-dot, matrix or LC displays require a human to spot them
You can simply fabricate the flap by cutting the flap to dimensions and affixing letterings onto them. That’s not possible with LCDs or LED arrays.
i.e. places where you want a very large display that's readable in direct sunlight.
If you were equipping a train station or airport in the 1980s, your options were split-flap displays, CRTs with sunshades over them (maximum size ~20 inches), a multi-CRT video wall ($$$$$$$$), a vane display (numbers only) or a flip-dot display. And a lot of places that were equipped with them in the 1980s still had them in the late 1990s.
These days you'd use an LED display, or a sunlight-readable TFT.
Many UK rail stations had them into the early to mid 00s. If I'm not misremembering, the boards at London Kings Cross were not moved to different tech until at least 2005. Manchester Piccadilly had them replaced around 2001 (at the time I was passing through there a fair bit, travelling between York & North Wales).
Part of the problem with the LCD signs is they show too much information. It’s not really an advantage to show the next 30 trains incoming on the big board when only the closest 2 or 3 have gates assigned. They also tend to be themed in colors that are harder to read (Amtrak does blue on white, which is harder to read than white on black). Some stations tried replacing the split flaps with single-character LCD displays to mimic, but they always ended up breaking faster (and never getting fixed) for some reason.
From what I recall in an article about these signs, industrial versions were ungodly expensive to begin with, but the real reason they’re being replaced is that the companies that originally made them are all out of business and you simply can’t get parts for them. It’s cheaper to replace an entire LCD panel than it is to fix one of the mechanical signs once and you don’t have to wait 6 weeks with a broken sign for parts to be manufactured.
- Image sharpness and contrast is excellent. You can read text on an old flip display far away that you would struggle to read on a modern LCD if you have mild astigmatism.
- Perfectly readable on a sunny day.
- They can show colored logos and symbols (e.g. train type, airline, highlight warnings)
- Better failure mode than LCD: single digits fail independently from each other and can be replaced. But it's less likely that the entire display fails.
- They are either working or stuck - no fading out like CRTs.
Also, contrary on what I have seen on LED matrices or other RGB/pixel based displays: they won’t display advertisement which otherwise manages to sneak in – too close to information.
Beyond just being a cool project, the detail in the README on Github is really amazing and I've bookmarked this as a great reference for releasing open-source hardware as a git repository. CAD files, a bill of materials, detailed usage instructions, etc.
It's also quite expensive, but has a clever design where the individual split-flap modules can be replaced.
There are also custom ones you can have made (probably even more expensive), but they're mostly targeting enterprise: https://www.oatfoundry.com/split-flap/
It'd be neat to have one you could hook up to some market API to make a little stock ticker.
Very cool to see work an open source design.
Glyphs can be loaded in an arbitrary order. For a given corpus (e.g. city names, American English digraphs) how does glyph order affect the time taken to update the display? Is there an optimal ordering?
If your display could accommodate 5% more glyphs, which would you add and why?
(With apologies to anyone revising for an exam this summer.)
This only applies if you have only one copy of each letter.
You can consider having more copies of frequent letters mixed into the stack, if the stack's thickness allows.
So have the alphabet ordered in descending frequency. But put a second block of the most common characters half-way through. For each word you first calculate the slowest letter, which gives you a 'budget' of how many flips you will take. Then each letter uses that budget to get to the optimal location of the character it needs to display, probably as early in the alphabet as possible.
If you know which word is being displayed _next_, you can also try to get into the best position to move to in preparation.
The ideal alphabet ordering might be different depending on position in the word -- for instance, some letters are more common at the start of a word. And you could think about digraphs, taking advantage of Q usually being followed by U.
He also sells blank "flaps" on Tindie [1].
The documentation on how to build the Split Flap is also really awesome [2], including how to cut your own flaps [3].
I've been following this project for a while. It's pretty awesome. I estimate about $10 per character (as opposed to the $180/character (!!) another poster mentioned through Alibaba), with a large portion of the cost being the custom cut "flaps" (in small quantities). It seems like the cost could get in the $2-$4 range per character but I couldn't figure out how to do it without a significant amount of labor involved in cutting the flaps.
FYI, there's also a company called Oat Foundry that sells large split-flap displays [4]. I seem to remember the cost being in the $10k+ region but I don't see a price and I could be way off base.
Oh, interesting, I see Vestaboard also has a (smaller) one for around $3k [5].
[0] https://youtu.be/UAQJJAQSg_g
[1] https://www.tindie.com/products/scottbez1/blank-split-flap-d...
[2] https://github.com/scottbez1/splitflap/wiki
[3] https://github.com/scottbez1/splitflap/wiki/Cut-flaps
Laser cutting a bunch of sheets at once could be one option, but material selection might be a problem: PVC releases chlorine when laser cut, which will do all sorts of horrible things to optics/the meatbag operating the machine. Maybe a cutting plotter will work, since you're using really thin sheets?
Doing a single cutout of PVC with a CNC would be fine, but doing 40x23x7 is probably not.
Doing a die punch is maybe possible but I don't really know how to create a custom punch and what tooling to use.
But only if you were doing a bunch of signs!
Just don't use PVC blanks.
Use a waterjet cutter instead. You'll have some issues with microplastics in the water, but these can be filtered.
There is the wazer, but it doesn't live up to its hype.
Delrin, maybe?
It's now possible to buy commercial split-flap displays from China. $180/char.[1]
A score display for a sports team might only do one or two rotations per week.
Of course, for a clock or airport flight display, it'd be a different matter!
Those flaps and wheels really want to be injection-moulded from ABS, with round pins at the flap ends. That would be cheap if you were making enough of them.
(I miss TechShop. They even had an injection molding machine good enough to do this.)
the techshop 2.0 guy was a travesty.
Had a quick look and the cheapest laser cutter appears to be around $400. The next one is $1500 and then the price just keeps on climbing.
Any first-hand experiences with laser cutters? An option suitable for an (occasional) hobbyist use, but not a total junk either.
Generally speaking, for cutting anything above paper or balsa wood, you will need module that costs around $500, higher power modules need decent power supply.
There are some laser cutters from china that claim to have such power for less, but there is not jet "consensus" on any of DYI forums/reddit's that any of them are good jet.
Generally cheap machines have compromises which mean more work for you - less reliable, less accurate, weaker laser, worse software - all of that means a lot more trial and error, a lot more burnt material and a lot more stuff you just can't do.
If you want to laser cut thicker materials, but only occasionally, you'd probably find it much more cost effective (and low effort) to either outsource or find a makerspace which has a decent machine. Laser cutting is quite easy to outsource as it is very easy to fully specify what you want (2D drawing + material specification is all you need).
As others have suggested, jobbing it out or joining a makerspace is often the best choice for occasional use.
The sound of Flap flap flap flap flap still in my memory
It looks like in this other project they just 3D print everything?
[1] https://old.reddit.com/r/functionalprint/comments/mtq0k8/sma... [2] https://github.com/barlowtj48/flipclock
Not sure why i like it, but i do.
https://robbreport.com/style/watch-collector/jacob-and-co-nf...