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Kinetic Chain Sculpture Built from a Bicycle

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I took an old bike, scavenged a 12-volt car seat-motor from another project to power it, and ran chain around the rear rim. I find it so mesmerizing it's almost dangerous to turn it on; I might spend an hour watching the various shapes travel through the moving chain. I didn't realize how cool this project would be until I had actually built and tested it.



Though this phenomenon is probably best described by pages upon pages of differential equations, my best simple explainantion is this: Think of a length of chain hanging and not moving. If you hit it, something like a wave will propagate away from the point at which you struck. Now fix yourself to a point on the chain, start it moving, and hit it again. From your perspective the wave propagates as before, at equal speed in both directions, yet from the perspective of a fixed external observer, the wave's speed and the chain's speed add in one direction along the chain, and subtract in the other. So for chain speeds close to the wave speed, waves will appear to sit at the same relative position or to move slowly along.

This "slowing down" effect is one of the reasons why I am so fascinated. In the moving chain, shapes that would otherwise change too fast to enjoy can be clearly seen.

The Exploratorium has a similar exhibit called the Lariat Chain.


might I suggest using some sort of rod to manipulate the chain instead of your fingers. hate to see them sliced off. other than that very very cool.
ewilhelm (author)  sgt_eldridge6 years ago
Not a bad suggestion, but the low-wattage motor tended to stall easily and really couldn't do any harm.
Make another with a chainsaw blade :D
These are great, my local science museum has a 10 foot one with thicker chain.

I made one out of knex once but the chain can only form shapes in one plain so it's not as impressive.
read the comments..dont you guys think making it work with black light would be cool..its like everything is dark except a glowing chain with weird patterns
COOL !!
love the way it looks slow motion
whats the rpm of the wheel?
extratooth24 years ago
 Haha, i love the socks with flip flops in the second vid.
ozetzioni5 years ago
Hey, I am building a pedal generator bike with a battery. at the end of the day i want to transfer the electricity i made of riding into a bigger battery and then use it for lighting equipment... anyone knows of a method to transfer the electricity from one battery to a bigger one without losing voltage or too much energy???
hlumbard6 years ago
What type of chain is that? I've seen similar things in a smaller scale using string in a hand held device.
ewilhelm (author)  hlumbard6 years ago
It's the chain that looks like a bunch of small hallow balls connected by straight pieces of metal. You can just make it out in the slideshow images.
You can usually find this stuff at bathroom hardware type stores. I've seen it labeled "shower curtain" chain, because many sliding-track shower mounting systems use it to hang the curtain... I think. Other than that, though, i think "hollow-ball-straight-pieces-of-metal" is a more functional title.
They have one of these at the Science Museum of MN. Its really fun to play with.
you know what the waves make me think of, in both the way you describe them and the way they look in the pictures. sound waves from a car. as the car gets closer the waves are closer to gether and as the car gets farther away, the waves spread out and the pitch sounds deeper. i bet you could paint on some IR reflective paint and use it for a synth of some kind.
Brennn106 years ago
That IS pretty amusing!
Gene Hacker6 years ago
I saw a huge one of these in the exploritorium. Very cool project indeed.
crapflinger6 years ago
does it make wild random shapes on it's own? maybe hook up some kind of cam or something off of the wheel hub that would introduce a "wave" randomly as the thing churned along? nifty! i really wish i had the time and space to set up some stuff like this....my dad would sit in a room for a month without moving if he had something like that
ewilhelm, you look cool :-) was this instructable filmed and done at the instructables office/ workshop/ place? :-)
ewilhelm (author)  GorillazMiko6 years ago
No, this is an old project I did - it dates to 2001 or so.
Oh, so you just posted it as a slideshow? Or you just never got the time to post it?
ewilhelm (author)  GorillazMiko6 years ago
I wanted to share the project, but I didn't take step-by-step photos, only pictures and video of the final things, so I made a Slideshow.
PKM6 years ago
I'd be tempted to paint half the chain white, the other half black to see the colour moving around the chain.. but I guess paint would make it not so flexible. UV security marker? UV makes everything cooler :) The other cool potential would be if you could synchronise a strobe light to the rate at which chain links pass a certain point, so the strobe would pick out each successive link at the same point and make the chain appear to be not rotating, or put a UV dot on every fifth link and strobe once every five links for a "dotted line" effect. Also, the low-res version of your avatar looks kinda like Jim Carrey and it's distracting me...
lilpunk13026 years ago
There's something like this at the Exploratorium in San Francisco, but instead of a hanging chain, they use a 1/4inch (ish) thick soft cotton string, run and run it vertically through a wheel. It behaved somewhat differently though, here we see the waves slowly move then "snap" off when they pass the bottom of the chain, but there, the string was shooting vertically, and whatever shape you contorted it to, it would keep as the string passes through. So the string shoots up, and as you shape it with your fingers it keeps the shape. It was quite stunning actually.