Thursday, February 20, 2014

Pi-powered T-shirt cannon

I went to a baseball match in Phoenix, Arizona a few years ago. (Go Diamondbacks!) It’s a remarkable cultural experience if you’re not American: and I am grateful to the man next to me who put up with a stream of questions (“Why has that number just gone up? Why isn’t he MOVING? Why does it stop every ten minutes? What is that giant plush hotdog thing? What sort of country carpets its stadia and serves beer at games? How is his leg doing that?”) not by killing me, as he must have been sorely tempted to do, but by sharing his packet of salted sunflower seeds.

I was reminded just how superficial my understanding of American institutions like baseball (or monster trucks, or roller derby, or that thing they call “football” that isn’t) is, and how much of that understanding has been gained entirely from watching The Simpsons. That baseball match had everything: dancing mascots, footlong hot dogs, an organ playing “Take me out to the Ball Game”, and a t-shirt cannon, just like the one that killed Maude Flanders. (This is not a spoiler. Maude Flanders died nearly fifteen years ago.)

Since that baseball game (where none of the t-shirts made it in my direction) I have had the odd daydream about owning a t-shirt cannon. It’d be great. I could use it to clothe people a long way away. David Bryan and a Raspberry Pi have made it all possible.

You’ll need a lot of PVC tubing, an understanding of both Pi the computer and Pi the irrational number, a compressed air tank…and sprinkler valves. Dave’s cannon’s not just a hobby project: it sees regular use at Minnesota Rollergirls events.

Dave has written a superb how-to, with detailed diagrams, parts lists, some help with the maths you’ll need, an explanation of how he came to the engineering decisions he made, all the necessary code, and much more. I must check up on the legality of letting the work experience kids near compressed air: we could use one of these ourselves for events.

Thank you Dave! (If you like the way Dave does things check out his cat feeder, which we featured here last year) – and RIP Maude Flanders.

 

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