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  • Sometimes you see, once you've spotted this you'll see it everywhere.

  • In graphic design you'll sometimes see a design

  • with like, three or more gears that are supposed to be meshing together

  • sometimes what you see

  • I-I guess I'll draw just sorta wheels like this

  • but they are supposed to have teeth like this

  • and then there will be another one here

  • and another one here

  • and this is supposed to be like

  • y'know three things that are working together

  • the students and the teachers and the parents all come together

  • to make this school work fantastically, or whatever it is

  • and you look at this thing

  • and if you think about what happens with gears

  • alright so-so if this one is going this way

  • then because these two the teeth are meshing this way

  • this one has to go this way

  • so that they, you know, because they have to turn against each other

  • and then whats this one supposed to do?

  • this one is saying that it's supposed to go around that way

  • and this one is supposed to [be] saying it's supposed to be going around this way

  • so nothing works, and so your school district grinds to a halt, or whatever it is.

  • If you happen to have a British two pound coin and you look on the back of it, you'll see there is this design

  • with gears, and various other things about technology and the industrial revolution

  • So, if you look closely, there's like 19 --well if you count them--

  • I guess you can't look and immediately count 19

  • But if you count them, right, there's 19 of these gears and 19 is odd

  • So like it goes this way, it goes this way, it goes this way

  • Odd means that it wont work. So, you know, your symbol of technological process, or whatever; it doesn't move.

  • So the question is, well, how do you get three gears that do move?

  • Is there a way to change the shape?

  • Like, you can't do in the plane, but if you go out of the plane, then what can you do?

  • So here's a few mechanisms that shows ways you can make this to go

  • So, these are, like worm gears. You get this, sort of, screw helix thing

  • And then the way that they work... Well you can see that it works and they are all, sort of, symmetrical around...

  • Let's see, maybe if you look directly down here, you can see that there is a symmetry between them.

  • RIght, so these three, sort of, worm gears... Because the way that they interact,

  • they don't have a direction in the same way as planar gears do (gears just on the plane)

  • and so you can get them to all work like this

  • although you do require this frame.

  • So this is another solution to the problem. It wasn't really a problem that needed solving, but there you go!

  • So this is, again, it's three gears that turn together, and they are, sort of, meshing with each other.

  • They have this other weird feature that they're all linking with each other. So they're sort of linked gears.

  • They stay in place. You can't actually turn one of them without turning all of them at once.

  • It doesn't move.

  • It's me and Saul Schleimer, it a guy who I work with these things.

  • So we made this thing and immediately people say

  • "Okay. Sure. You can make it go. But can you, like, drive it with a motor?"

  • And then, what we ended up figuring out is, like... So here's another, sort of, helical worm screw thing

  • and then. Whoops. So you can see that it's sort of climbing down and as it's going, it is making them go.

  • So, to answer the question about how do you make it drive itself...

  • So here's this, sort of, base that you can put it on.

  • And the gears just sort of slide in there. And then, if you pull this through, then it makes it go.

  • Or if you just turn it.

  • This helix thing turning is, sort of, the same thing as moving it, as translating it

  • So, if you turn it, it makes the gears go.

  • Or if you push it through, it also makes the gears go.

  • *grinding sound*

  • This is, sort of a... ...another variant on that same idea.

  • These gears aren't rotating gears, they are, sort of, sliding gears.

  • All of these have, like a, an axis of symmetry. So, there you go.

  • So... *scoff*

  • So these... I mean you can see these teeth that make it do that.

  • Let's see if I can do this weird thing. Let's see. So...

  • So the illusion, if I move it just right, is that the one I'm not holding doesn't move.

  • I don't know if you're getting that. So the one that I'm not touching is supposed to sort of hover in the mid air

  • And while the other ones move. It's, sort of, a weird effect because...

  • ...cause it doesn't look like I'm directly controlling it.

  • I don't know how good I'm doing that.

  • You can fix this in post, right? You can just stabilize on it?

  • Then you'll be fine! Right?

  • Brady: *giggles*

  • ...of the gaps between the primes as well. You see that some are short...

  • *ticking*

  • Oh, that was nice! That was satisfying! A nice long gap. It's really nice!

  • I mean, it's a bit of silly fun. There is no practical use to anything, but I love it!

  • *ticking*

Sometimes you see, once you've spotted this you'll see it everywhere.

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A2 sort supposed worm move helix teeth

Three Gears are Possible - Numberphile

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    林宜悉 posted on 2020/03/27
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