Illustrator Tutorial - Create a 3D Cog Wheel - Part 1
This is a fairly advanced tutorial which will use tools and techniques you may not be familiar with.

1. Start by drawing a shape like the one on the right. To help you, make sure the Rulers are visible (VIEW...Rulers) and drag in a couple of guides.

The three circles are made by using the Ellipse Tool Ellipse Tool with Shift held down to create perfect circles.  Tip: If you place your cursor exactly where the guides cross and hold down Shift and Alt. and drag away from the centre, your circles will be perfectly 'centred'.

This will help you to draw the main circle and the central circle.  Draw a smaller circle above the centre point and the topmost shape (which will become the 'teeth' of the cog wheel) is drawn by using the Rounded Rectangle Tool Rounded Rectangle Tool.

Cog 1

Select this rounded rectangle, click on the Rotate Tool Rotate Tool and - with your cursor exactly where the guides intersect - Alt + click.

This will bring up the 'Rotate' dialog box.  Now, we will want to have sixteen 'teeth' on our cog.  The circle is 360°.  Therefore, 360 ÷ 16 = 22.5.

So, we enter 22.5° in the Rotate dialog box and click OK.

Cog Rotate



And to the right we see the effect - the 'tooth' has been duplicated at 22.5° to the original tooth.

That's fine, but how do we duplicate this action to create the rest of the teeth?

Cog Copy
With this second tooth selected, simply press Ctrl + D to duplicate the tooth.  The image to the right shows how we start this process and, if you roll over this image, you will see the finished result. Duplicating the cogs
Now we're going to do basically the same process with the small circle on our cog. Select this small circle, click on the Rotate Tool and Alt + click where the guides intersect.This time, we only want eight 'holes' in the wheel so, in the Rotate dialog box, enter 45° Rotate cog
Now press Ctrl + D until you have duplicated this smaller holes as the image on the right. Finished cog
Now press Ctrl + A to select all the objects on the cog wheel. Cog-Select All

We are now going to use a tool introduced in Illustrator CS5 - The Shape Builder Tool Shape Builder Tool.  Click on it (or press Shift + M).

Hover your cursor over one of the internal holes in the wheel (it will show a 'hatched' pattern), hold down Alt (a 'minus' sign will appear next to your cursor) and click.  The hole will be 'punched' out of your wheel.  Repeat for each hole until they have all gone.

Cog Exclude Holes
Taking shape! Cog without holes

Now with the remainder of the components still slected, look at the Pathfinder palette (WINDOW...Pathfinder) and click the 'Merge' icon.

The components will now all be merged into one object.

More on the Pathfinder palette.

Cog merged
Finally in this stage, if your cog wheel has a stroke, select all the cog wheel components and change the 'Stroke' in the toolbar colour picker to 'no stroke' by clicking the white icon with a diagonal red stripe.No stroke
  Part Two >>>
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