Open source “split-flap” mechanical display

by deeyago • 5 years ago

293 90 5 years ago

techdragon• 5 years ago

This is just awesome on so many fronts. I love the automatic update of the BOM using GitHub actions, it’s such a nice touch.

Animats2• 5 years ago

Moving parts made of acrylic, though. Will not wear well.

Delrin, maybe?

It's now possible to buy commercial split-flap displays from China. $180/char.[1]

[1] https://splitflap.en.alibaba.com/

michaelt2• 5 years ago

For some applications you wouldn't worry too much.

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!

jiveturkey4• 5 years ago

eh? It's DIY. Make them out of whatever you like.

Animats2• 5 years ago

They're intended to be laser-cut, which limits the materials.

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.)

gibolt• 5 years ago

Related video on Flip Clocks from Technology Connections: https://youtu.be/ZArBfxaPzD8

s0rce• 5 years ago

After watching this video I feel like every website is showing me flip flap displays.

smnscu2• 5 years ago

I really enjoy Alec's videos and quirky humour. Beware though, this kind of channel is a massive, addicting time sink. Other similar channels that HN might appreciate (the first two are quite well-known, the last one I found recently and is definitely bingeworthy):

- 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

TonyTrapp• 5 years ago

Beware though, this kind of channel is a massive, addicting time sink

Luckily he only posts new videos every few weeks. ;) And almost every one of them is time well spent.

iCarrot• 5 years ago

Also check Ben Eater's for computer stuff https://www.youtube.com/c/BenEater/videos

jamestenglish• 5 years ago

Subscribed to all 3 of those, one of my new fav's

Stuff Made Here: https://www.youtube.com/channel/UCj1VqrHhDte54oLgPG4xpuQ

ziml77• 5 years ago

Tech Ingredients is another good one with nice, long videos: https://www.youtube.com/user/TechIngredients

mastax2• 5 years ago

- Marco Reps - Electronics, Metrology, Machining, etc. With a dry German sense of humor. Like electric This Old Tony https://youtube.com/c/MarcoReps

jedimastert• 5 years ago

Stuff like this is why I have difficulty giving up YouTube. I've given up basically every other algorithmic feed (except for HN, I suppose) but the amount of passionate and engaging education and curiosity content on YT will have me hooked for a while I suppose...

Benlights• 5 years ago

I've found that watching Alec's videos at 1.25X speed made them more enjoyable and listenable.

teh_klev• 5 years ago

I watched that last night. Alec's a tremendous educator and come a long way since his early videos (which are also still good). I really enjoyed his deep dive into how dishwashers work :)

gorgoiler• 5 years ago

Fantastic.

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.)

grishka3• 5 years ago

You can only flip in one direction, so the time taken to update is entirely dependent on the previous state. Worst case you'd need to display the previous character (B -> A for alphabetical order) and would have to flip through the entire alphabet to get to it.

nine_k• 5 years ago

You can only flip in one direction, so the time taken to update is entirely dependent on the previous state. Worst case you'd need to display the previous character (B -> A for alphabetical order) and would have to flip through the entire alphabet to get to it.

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.

agys2• 5 years ago

We made a small project with all the 6 letter words from the Italian dictionary (as an homage to the inventor and producer of the split flap display: Solari from Udine) ordered in a way to produce “the least effort”.

https://vimeo.com/250121964

aliljet• 5 years ago

I've long hunted for split flap modules on aliexpress and I know folks who buy old train boards to get these modules. I wonder if there's someone out there scaling up the manufacturing? I'd love to buy modules at under the DIY ~$50 mark and build cool stuff at home!

tartoran• 5 years ago

The randomness factor is quite mesmerizing, each flap search ending at a different timing along with the mechanical aspect make this a very fun thing to watch. Old tech was so cool..

gonehome• 5 years ago

I've always loved these - this company makes one that looks great, but isn't open source (there is an API that has yet to be released): https://www.vestaboard.com

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.

chrisdalke• 5 years ago

This is great! Love seeing hardware hacks like this on HN :)

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.

raverbashing• 5 years ago

Airports in the 80s/90s were all about those displays

The sound of Flap flap flap flap flap still in my memory

abetusk3• 5 years ago

Scott Bezek has a great video on "How a Split Flap Display Works" [0].

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

[4] https://www.oatfoundry.com/split-flap/

[5] https://shop.vestaboard.com/products/vestaboard

murderfs• 5 years ago

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.

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?

abetusk3• 5 years ago

Laser cutting is straight out for the hobbyist, because of the chlorine, as you correctly point out. I think the way to do this is either with a CNC or with some die punch solution.

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.

mschuster913• 5 years ago

Laser cutting a bunch of sheets at once could be one option

Use a waterjet cutter instead. You'll have some issues with microplastics in the water, but these can be filtered.

thunderbong• 5 years ago

This HN post has been submitted by Scott Bezek linking his github source code

oxplot• 5 years ago

These screens are awesome. I did a design a few years ago, aiming for super low cost and easy build. Made a few units but it needs more refinement: https://splapr.com/

huhtenberg• 5 years ago

laser cut enclosure

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.

unionpivo• 5 years ago

Stay away from anything cheaper that 1k at the moment.

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.

leoedin• 5 years ago

My local makerspace has a really good laser cutter which members can use. It works well for that kind of usage as there's not too many ways you can kill it or yourself.

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).

thechao• 5 years ago

Do you have a suggestion? I feel like the last time I looked into laser cutting, it was either SEOd hits that were crazy expensive or shops that looked dodgy. Nothing in-between.

NathanielK• 5 years ago

For home gamers, keep in mind the price of the machine is only one part. Large laser cutters are expensive to ship (from china), and take up a big space. Most materials will also require adequate ventilation.

As others have suggested, jobbing it out or joining a makerspace is often the best choice for occasional use.

pault• 5 years ago

You can send your designs to ponoko for small batches. Much cheaper than buying a laser cutter unless you plan to scale up.

fortran77• 5 years ago

We need to vent our laser cutter to the outside. There's also considerable danger that what you're cutting catches on fire, so they need to be supervised. It's not just the cost of the machine--they're not just "plug and go"

theodric2• 5 years ago

I bought a 50*70cm "60"-watt unit online for about €2000 shipped. It is the size of a chest freezer. It works reliably, except that if you don't power it up with the laser armed, and instead flip the safety switch after power up, it will not fire the laser. I had one Hall effect endstop fail, but everything apart from the enclosure itself is COTS commodity stuff, so I just got a pack of new endstops on eBay and fixed it. Cooling with an Ikea tub full of water, vent with a hose out the window.

argvargc2• 5 years ago

Genuine question: what are some practical advantages of a split-flap display over, well... any other kind of dynamic character display?

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?

danohuiginn2• 5 years ago

Nostalgia, really -- I have fond associations of these with childhood train journeys.

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.

argvargc2• 5 years ago

That sparked an interesting idea: would these work in a zero-gravity situation (mechanically I mean), and if not, how to adapt them so they would?

(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.)

mjhagen• 5 years ago

I used to have one of these, but left it above the radiator. All flaps warped beyond repair :( So if you're going for resistance to harsh environments you'd have to source a better material for the flaps, at least.

gattilorenz• 5 years ago

similarly to an e-ink display, it doesn't take energy to show the current/last status, it's required only for transitions. If there's a blackout, the display is still visible.

goodpoint2• 5 years ago

If there's a blackout, the display is still visible

And dangerously out of date in airports and train stations.

When they break down they had to be covered to prevent misleading passengers.

CyanDeparture• 5 years ago

To me it's as simple as they look really cool and satisfying.

mschuster913• 5 years ago

- they don't require energy to maintain their state - a property which they share with eInk displays, but a split-flap display is unrestricted in size.

- 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

aubergene• 5 years ago

The contrast is very high, so easy to read in bright sunlight

prennert• 5 years ago

There is the advantage of extremely high resolution and crisp contrast. The digits can be printed in any colour and on (kind of) any texture you like. It scales also very well to very large displays.

numpad0• 5 years ago

They offer high resolution full color semi-dynamic display without needing any semiconductor circuitries.

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.

michaelt2• 5 years ago

The traditional uses of split-flap displays were sports arena scoreboards, airports and train stations.

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.

vidarh• 5 years ago

When I was a kid our hifi-system had a split-flap clock built in (around 1980 or so)

tyingq• 5 years ago

Worth noting not all LED displays are sunlight readable. Typically, outdoor requires old fashioned through-hole, separate LEDS, and at least 1/4 duty pwm refresh.

dspillett• 5 years ago

And a lot of places that were equipped with them in the 1980s still had them in the late 1990s

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).

mastax2• 5 years ago

I had never realized that the original Sony Jumbotrons were CRT (one CRT per pixel) https://youtu.be/AclwH64eAkU

wayoutthere• 5 years ago

As someone who used to travel a lot by rail in the not so distant past, every station that replaced one of these boards was a downgrade. Most stations had maybe 1 or 2 of these signs with the rest of the smaller ones already LCDs, so it’s not like there weren’t already places to get the info you couldn’t show on a sign like this.

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.

theodric2• 5 years ago

Zero power needed to retain image, not encumbered by e-ink patent and manufacturing monopoly, simple and repairable, and you can build it yourself at home

goodpoint2• 5 years ago

- Visibility angle is much better than any other alternative. This is crucial when one big display is used in a very large room instead of many small displays.

- 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.

protomyth• 5 years ago

- oddly pleasant sound indicates change in data

agys2• 5 years ago

Readability and ultra low energy consumption (plus: they are awesome and produce a soft sound like a distant waterfall).

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.

0xffff2• 5 years ago

I wonder how their energy consumption actually compares. Electric motors moving relatively heavy physical cards is far from free. I wouldn't be surprised at all to find that an eink display beats the pants of of a split flap display in terms of energy consumption, but I don't have the necessary equipment to test it.

amelius2• 5 years ago

I'd buy a watch with this type of display.

dole• 5 years ago

How about an NFT watch with a split-flap that displays crypto?

https://robbreport.com/style/watch-collector/jacob-and-co-nf...

sva_• 5 years ago

Frankfurt airport has a huge split-flap display to show departures[0]. I love looking at it changing the data, and hope they'll never replace it with a digital one.

[0] https://www.youtube.com/watch?v=cj32w5z81Ak

rjsw• 5 years ago

The sound it makes lets you know when something has changed, you don't need to keep looking up from whatever else you are doing.

jcadam• 5 years ago

Still? Good to know :) Last time I went through Frankfurt was back in '06.

axolttl88• 5 years ago

They were installed as useful & beautiful features in the Qantas First Class lounge at Sydney International Airport, and are much loved:

https://theluxurytraveller.com/2019/03/review-qantas-first-c...

anonu• 5 years ago

I've looked into buying ready-made solutions. Vintage split-flap mechanisms go for close to $1000 per character on eBay. There is a company I found in China that manufactures these, but its still around $300 or so per character. Displaying a tweet would cost close to $100k after shipping, etc...

pg_bot• 5 years ago

https://shop.vestaboard.com/products/vestaboard?hsCtaTrackin...

aliswe• 5 years ago

Id like to make these in arabic ... Would deffo be a big challenge with all the shapes though.

mhb• 5 years ago

adkadskhj• 5 years ago

I wonder how easy and cheap i could make these? Would be neat to slowly grow a stack of these on the wall with some Pi controller and feed Wifi messages to it.

Not sure why i like it, but i do.

nonninz• 5 years ago

A nice coincidence, this was on my homepage of Reddit this morning: Smart flip clock with weather tutorial [1], [2]

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

singularity2001• 5 years ago

someone make an ebook reader of this (miniaturized of cause)

hinkley• 5 years ago

I wonder if there’s a way to speed up the rotation rate by making the stop adjustable. It matters more if you try to go beyond A-Z0-9

Open source “split-flap” mechanical display

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