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# Animating a chain and sprockets in AE

COW Forums : Adobe After Effects

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 Animating a chain and sprockets in AE by jim branstetter on Jan 25, 2010 at 8:26:51 pm

Hi All.

After viewing Chris Zwar's great tutorial on animating gears in AE ( http://library.creativecow.net/articles/zwar_chris/cogs2.php ) and after trying it out. I wanted to try to connect the gears using a chain, similar to this link but in 2d not 3d (

)

Any Ideas, suggestions, tutorials?

Thanks a bunch.

Jim

 Re: Animating a chain and sprockets in AEby adam taylor on Jan 27, 2010 at 10:04:37 am

Carl Larsen did a useful tutorial showing how to use expressions to accurately rotate wheels to look like they are rolling across a surface. I seem to remember they also worked for different sized wheels
I'm sure those expressions could be useful in figuring out your problem.

http://library.creativecow.net/articles/larsen_carl/vehicle_rig.php

Video Editor/Audio Mixer/ Compositor/Motion GFX/Barista
Character Options Ltd
Oldham, UK

http://www.sculptedbliss.co.uk

 Re: Animating a chain and sprockets in AEby Ryan Hill on Jan 28, 2010 at 9:35:53 pm

It's going to be a lot of trig to figure it out.

Each link in the chain will pass through four states.
1) On the first gear
2) Passing from the first gear to the second
3) On the second gear
4) Passing from second back to first

If you can solve the total length of the chain, you can solve the speed each link will move around the chain's path in terms of the speed each gear rotates.

To solve the chain length, you need to solve the length for each of those four parts. The angle around each gear that the chain passes along will add up to 360, so if the larger is 190 degrees, the smaller will be 170.

The tricky part to me is how to figure out what those two angles should be.