Getting a centred line in Illustrator

In Illustrator 10, you can easily get a line centred between two other lines using the align palette. If you don't know how, this is how you do it:

1) Create a simple vertical line. You can use the line tool set to 90 degrees or just hold shift when drawing with the pen tool to constrain it to the 90 degree angle.

2) Make a copy of this line and move it aside a good length. These two lines will now act as your border/edge lines.

3) Now make a another copy of one of the line and put it roughly in the middle. For the sake of the tutorial, I changed the colour of this centre line.

4) Select all three lines and click on the 'Distribute Objects: Horizontal Distribute Center' button in your Align Palette.
If you haven't got the Align palette open, you can find it in you top menu under Windows > Align.

Now your middle line is centred exactly between your border/edge lines.

Basically, if you had 5 lines in a row, they would distrubute evenly. This is a handy tool for setting up quick custom grids of measuring reference tools.

Easy, huh?

So, everything is peachy keen here BUUUTTTTTT what if you have two curved lines and you want a curved line in between. For example, below is a quick dagger blade I am drawing.

What I want to achieve is the red middle line as shown in the image. You can just draw it simply but you can get a more accurate version the following way.

1) Just quickly, I have created the two outer lines which are the edges of my dagger blade. You will notice that the lines are both different colours. That is to show you that the two lines are separate not joined. This point is crucial because the blend tool, which is what we are going to be using, works by mixing two separate objects.

2) So, select your two lines then go to Object > Blend > Blend Options.

3) Change 'Smooth Color' to 'Specified Steps' and enter '1' as your number.

4) Nothing has changed yet because you haven't applied the blend yet (I supposed I'm doing this a bit in reverse for now... Oops!). So go to Object > Blend > Make Blend.

5) Viola! You have your centre line. Now all you have to do is to expand the blend and set the colours of your lines to black (or whatever colour you originally intended them to be.

If you wanted your dagger to have flat sides then set the number to '2' instead of '1' in step 3.

Also, when you make a blend, you might get something odd like below.

This is because when the blend is calculated, it uses the first point in the path as a reference point EG you drew the first line from top to bottom and the second line from bottom to top. To fix this, you need to select the blend tool in your tool box and select the two reference points manually, which should fix the problem.

Finally, if you want a bit more of a precise ratio, say you want the line to be a quarter of the distance to one edge instead of exactly in between (IE at half the distance) then just set your steps to '3' then, when you expand the blend, you delete the other two unnecessary lines.

I hope you enjoyed this tutorial and found it helpful.

Regards,

Mix Mash

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