After Effects

Looking Back: Cogs & Gears

Original article: Creating cogs and gears in After Effects

Creative Cow tutorial - creating cogs and gears in AE
Creative Cow tutorial – creating cogs and gears in AE

This is a 5-part behemouth of a tutorial that I wrote a few weeks after finishing the morphing tutorial. I needed to animate some cogs for a corporate presentation and was faced with the problem of how to create cogs in After Effects. When I figured out a solution I was so pleased with myself I wrote these articles as a self-congratulatory exercise.

The original problem that I faced was – how do you get an image to follow a path without changing its size? I needed to have the teeth of a cog wrap around circles of different sizes, but without changing the size of the individual teeth. The solution I came up with was to use the Path Text plug-in, which allowed you to have text follow a mask shape, and use text to create the teeth instead of an image.   So the trick I devised was to build cogs and gears out of letters and punctuation marks…

Looking back this tutorial is dated in several ways but the most obvious is that the Path Text effect is now obsolete – replaced by Text Layers.  I think Text Layers were introduced with version 6.0, although it took so long for me to have the software upgrade approved by the accounts department that I eventually jumped straight from v5.5 to v6.5. The basic principle is still valid and so you could still use this process for creating cogs and gears but use Text Layers instead of the Path Text effect.

There is now a 3rd party plug-in available to distort an image along a path so you could make your cogs and gears that way – Rakka – but not everyone likes buying 3rd party plug-ins.

One thing that has always bugged me is that I rushed this tutorial out the door and the resulting cogs & gears don’t really look that good. If I had spent more time the end result would have been much better – the cogs & gears look flat (no texture) and the colours are garish (no colour grading) and so on…

… however the thing that has embarrased me even more is that I spend ages in part 4 describing how to use trigonometry to animate a piston, completely oblivious to the fact that Dan Ebberts had already posted a much more elegant tutorial on the same thing.  In fact the approach I use with trigonometry is actually incorrect and has a bug in the code, but since November 2002 only 1 person I’m aware of has discovered it and emailed me.

So to summarise:

– Path text is obsolete and you would use Text Layers instead

– The Cycore FX Rakka plug-in is an alternative approach to text

– The textures don’t look great and the colours need grading

– The trigonometry in part 4 of the tutorial is simply wrong, Dan has a better method.


With the release of After Effects CS6, it is now possible to use the same basic technique to create fully ray-traced 3D cogs inside of After Effects. This video tutorial at the ProVideo Coalition demonstrates the process…