Part Two: Creating Cogs and Gears in AE
Part Two: Creating Cogs and Gears in AE 5.5
CreativeCOW Adobe After Effects Tutorial
Creating cogs in After Effects (bought to you by the letter “V”)
Chris Zwar Chris Zwar
Entertainment Media
South Melbourne, AUSTRALIA

©2003 Chris Zwar and All rights reserved.

Article Focus:
This tutorial from Chris Zwar is a bit of a one trick pony, but it’s a trick that’s worth knowing. Cogs and gears are nice looking design elements and are popular in all sorts of backgrounds. If you do a search on the internet, it’s easy to find a range of techniques for creating cogs in Photoshop and Illustrator, and Illustrator even comes with a few included. This is part two of a four part series.

No Movie for this part Project files .sit Project files: .zip

---Part Two: Making our Cogs Look Nicer---

In our first tutorial, we saw how the Path Text effect can be used to create cogs of different sizes that can be animated with each other.

This tutorial shows how exactly the same technique can be combined with a range of textures to create cogs which look nice as well.

The textures included with this project were downloaded from various Internet sites which offer free textures. If you want to find your own textures, just go to Google and do a search for “texture free” and you’ll find heaps of useful links. Or you could run around with a Digital Camera and make your own.

Once again, the font which you use to make your cogs is critical in determining their final appearance; so don’t feel restricted to Arial Black. However, all cogs which you intend to animate with each other should be constructed from the same font.

Open up the project file we created in Part 1. (Or download the project files from the green bar above and follow along.)

This time our cog will have 36 teeth, so create a new composition which is 320 x 320 pixels in size, with square pixels.

Add a solid the size of the comp. This time, we’ll be building up our cog from different layers, so to keep things organized name the solid “teeth”.

Exactly as we did in our first tutorial, copy and paste the path text effect from our first cog, and when the dialogue box appears select the Arial Black font and type in 36 capital Vs.

In the path text effect settings, change the centre of the circle to be 160 x 160, which is the centre of our current composition. Change the X value of the tangent to be 160 as well, so we only need to change the Y value to alter our circle.

All our Vs are wrapped around the centre so drag the Y value of the tangent until we get something which looks more usable.

Because we need accuracy, ensure the layer is set to best quality.

When you think you’re getting close, zoom in to 200% to ensure the spacing is just right.

This looked OK at 100%, but at 200% we can see it isn’t perfect.

A value of 295 for the Tangent’s Y position fixes everything up nicely.

So the teeth of our cog now look like this:

Once again, we’ll add a new mask, change it to a circle, scale it to fit inside the teeth, and apply the stroke effect with a brush hardness of 100%. All of these steps were detailed in the first tutorial.

Now that we have our shape, we can add some texture.
I chose a fairly weathered looking metal texture, which I dragged into the composition, under the Teeth layer.

All we have to do is set the Teeth layer as a track-matte for the Metal texture.

Which gives us this:

Using this basic process, we can quickly begin to build up a nice looking cog.

I decided to add a central hub made of a different metal, so I added a new solid and called it “Hole in Middle”.

All I needed on this layer was a circle, so just as we’ve done before, add a mask, change it to oval, scale it down and apply the stroke effect with a brush hardness of 100%.

In the settings for the stroke command, change the selector to “on transparent”. This makes our solid transparent except for the stroke.

Adjust the size of the brush to suit – I settled on 11.

Choose another texture to your liking and drag it into the composition. I chose a much rustier, browner metal. Place the texture layer under the Hole in Middle layer.

Then apply the Hole layer as a track matte for the texture layer – just as we did earlier.

Which gives us this:

So we’re getting there.

Our Path Text tool can do more than just make teeth. We’ll use it again to make the inside of the cog more decorative.

Create a new solid and call it “Bracing”.

Apply the Path Text effect again and this time type in 12 capital Xs.

Your composition will look like this:

By now you should be pretty familiar with the Path Text tool, so type in the following settings:

  • Change the shape to circle.
  • Change the centre of the circle to the centre of the comp – 160 x 160.
  • Change the Tangent position to 160, 220
  • Change the Character size to 40, the tracking to .2, and the Vertical Scale to 150%.
  • Change the colour to white.

Your Xs should be evenly spaced between the teeth and the inside hub.
Next, add two masks, change them to ovals and scale them so that there is one on the outside of the Xs, and one on the inside.

Apply the stroke effect, set the brush hardness to 100% and adjust the brush size to suit. In this case, I’ve used a separate stroke effect for each mask so that they can be different sizes. You can choose which mask is being stroked in the pop-up menu.

As we’ve done before, choose a texture and bring it into the composition, just under our Bracing layer. Apply the Bracing layer as a track matte to the texture, which should give you something like this:

As a nice touch, we’ll add some holes to the inside rim, again using the Path Text effect. Cogs often have holes punched in them to save weight.

In the same layer – the Bracing layer – duplicate the Path Text effect which we used to create our Xs. This time, type some bullet points – 12 is a nice number. On a Mac, they’re option-8, Windows, alt-7.

Without sounding like a stuck record, you can use any font you want – so this is a great time to use some of those wacky Dingbats you thought you’d never need.

As we’ve done before, adjust the settings in Path Text so the bullets are correctly positioned – however this time we need to do two extra steps.

Firstly, click “Composite On Original” so our bullet points are added to the other stuff in this layer.

And secondly, because we’re cutting holes in our cog we need to change the colour of the font to black.

To make your bullet points evenly positioned, the following settings worked for me:
A Y tangent value of 124, a character size of 40, and tracking of –1.2

Because we’re using white for the solid areas of our cog, and black for the holes, we need to change our track matte method from alpha to luma. When we use an alpha matte, the back areas are still considered solid, they’re just coloured black. When we use a luma matte, the black areas become transparent.

Now that you can see everything, you may want to tweak your various bits and pieces to make it all look a bit nicer. It’s up to you.

I was happy when I got to this stage:

As a final touch, I decided to add two rings of a much brighter metal, one for the inside and one for the outside of our bracing. By now you should know the procedure fairly well, so we can skip some of the details.

So add a new solid and call it “Rings”. Add two masks and scale them so one is on the border of the bracing and the teeth, and the other is between the Hole in the Middle and the inside of the bracing. Apply the stroke effect and set the brush size to suit – I was happy with a size of 3.

Choose another texture for these rings – I went for a goldy type of metal. In this case, the texture was smaller than the image so I just scaled it up. Again, the texture layer goes underneath our Rings layer, and we set the Rings layer as an alpha track matte.

Which gives us this:

To top the whole thing off, I wanted a sort of uniform texture to go over the whole thing, to make the different components look more integrated.

Drag in another texture and put it at the top of the composition. Make sure it is large enough to cover the entire cog.

In the timeline, click the box with the T.

This is the Preserve Underlying Transparency option. This makes our current layer only visible over the layers underneath. Anything underneath the layer which was transparent remains transparent. Which gives us this:

Now we can see that out top texture layer has taken on the shape of all the layers underneath it.

We can now choose a layer transfer mode and a transparency option that looks nice.

I chose the “linear light” transfer mode with an opacity of 25%. To make it a bit punchier, I also added the “Brightness & Contrast” effect, and set the contrast to 15.

And that’s it.

By using nothing more than Path Text, with different letters and some bullet points, and stroking some circular masks, we’ve come up with a nice looking cog which will animate with any other cogs constructed with the same settings.

Now that we’ve used some very basic processes to create a nice cog, Tutorial 3 will show how to create some other interesting shapes – including a worm gear and a ratchet.

At this stage, I suggest you have fun and create as many different looking cogs as you can. As long as you use the same font settings, you can build up a library of still images which will all animate with each other.

---Finished here? Go on to the next part---

If you think that these cogs look a bit ordinary, then move onto the next stage, where we use exactly the same techniques to make more decorative looking cogs.

In part one, we look at the basic concept behind making cogs in After Effects, using the Path Text effect. This will demonstrate our “trick” in detail.

In part three, we extend the same techniques to construct a worm gear.

And part four demonstrates how we can use simple expressions to create amazing animations using the parts we created in parts 1, 2 & 3.

--- Chris Zwar

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