How to make Flip Clock Numbers and build a "like"-counter around it? Answered
So I've got this client, who's absolutely crazy about the "FLIKE" (A physical like counter.). But he can't have it for another couple of months, and he'd like it to be a little more custom... Long story short, I might end up making a similar product in a few weeks.
it will probably consist out of 5 digits and if it's up to me (not sure what the client wants) I'd stuff them behind a long picture frame. Something like this but actually mechanical and not just a picture of it:
So I started googling every hardware piece I needed and it turns out it's a huge pain to find Flip Clock Numbers / Flip Board Numbers... whatever you want to call them. (What's the right name btw?) You can't just buy these things, let alone in a custom size.
So the idea is to build them myself. I found this on wikipedia, which gives a clue about the inside:
So I'm figuring out what needs to go in it to make this work. (I'll end up making an instructable about it)
The numbers themselves are going to be made out of vinyl stickers. You can easily buy those from ebay in about any size if you look for them. The stickers will be put on to plastic boards. But I'm not totally sure what kind I should get. They should be thin and must be able to stand up straight, yet "easy" to fold. I'll probably get them lasercut, but you should be able to cut them by hand as well.
Currently I'm thinking about gluing small metal or carbon rods on the back of those letters. Although I'm not sure if that would be strong enough. Would it be enough to file one side of the rods to get a bigger contact surface? (What do you guys think?)
I'm planning of putting the half letters in a drum of ABS or PLA. it should be shaped like this: |--------|
I'm thinking about 3D printing this. But no idea how it'll do...
One side of the drum will be connected to a small stepper motor (5.625° with 1/64 reduction). I don't have real experience with stepper motors, but this resolution seems more than sufficient. The other side will be connected to a metal or plastic positioner. Each digit might end up with it's own "unit" so I can swap them separately if they'd break. I've got great experience with lasercut plexi, so I might use that because it's more accurate than wood and I might have some lying around.
I was first thinking about 1 stepper motor and a set of gears. I decided not to do that in the end because I don't have good experience with making gears and I can never find the right sizes online. Also, it'll make everything way more complex.
So each motor will have it's own controller connected to it. Those controllers would have to talk to an ATMega or something. (I'm planning on using an arduino to prototype, but then just swap the chip and make a stand-alone version without usb etc)
The ATMega has to be connected to the internet of course to get the current number of likes, so I'd connect it to a raspberry pi via I²C. I'm not familiar with the GPIO pins on the pi so I figured this would be a save and convenient way to handle this. The ATMega is robust, and I love the Arduino bootloader. A sketch is written in no time, but I have no idea how to start writhing this code for the GPIO pins.
So why the Raspberry Pi? First off, this thing might end up being wireless, and since a wifi module for the arduino costs as much as a Pi, I figured this would be easier. The plan is to make the pi run python script that could ask the number of likes from the facebook API. Once returned, it'll send +1 or +5 or +10 over I²C. The arduino shifts the numbers to the correct position and replies with the total number it's displaying (3012 for instance). The PI can then recheck if everything is in sync.
As for the set up. Since we have Pi, we can put on a LAMP stack (I know, this is overkill, but it wouldn't hurt either). So for initial set-up, we'd connect the counter to ethernet, browse to it on a different computer via "http://counter.local". And we'd be presented with a web interface. You'll be able to set the URL of the page u want to get the likes from, set and reset the number that is displayed on the counter, and the WIFI settings.
The WIFI settings can be saved in the wpa_supplicant.conf file and on reboot it'll automatically connect to this network. From now on the whole system is manageable over wifi via a html interface. For debugging I might enable ssh though.
So I guess you've got the whole outline now. I'd like to get your feedback on this! And this for the mechanics, electronics, and software side of things!