The proportion wheel is a tool used to figure out how much bigger you need to draw art, or how much smaller you have to make art to print it. It has three main parts.
You can set a proportion wheel in one of two ways.
1) You know the final print size, but not the original size.
Let’s use a print size of 4″ x 5″ as an example.
Find one of the final dimensions on the inner ring. Say 5″. Set the number in the window to the proportion you want to use (in the picture, it’s set to 150—that’s 150%)
Match up the number on the inner ring with the number on the outer ring to find 5” at 150%. It’s 7.5″.
So that’s one of the dimensions. Now, without moving the rings (because both dimensions are being sized up 150%), find the other dimension on the inner ring (4″) and then match it up with the outer ring. It matches up to 6″. so you need to draw your original at 6″ x 7.5″. If you’re metric, the same principle holds, of course.
2) You know what size your art is, and what size the final print size is, but you don’t know the reduction.
For example, let’s say the original art is 10″ x 15″ (a standard size to draw comics originals) and the final print size is to be 4.75″ x 7.75″ (which is the size of the print area in a digest-size minomic).
In this method, you line up the length of the original art (on the outer ring) with the length of the print size (on the inner wheel) and look in the window to see what number is at the pointer.
Then, you do the same again, but with the width of the original, and the width of the print size.
Why do you do this twice? Well, You saw that you came up with two different numbers. If the art and the printed page are not exactly the same proportion (and they rarely are) you will get differnt numbers for the length and the width proportion. You have to choose the smaller of the two.
Why is that? If you use the bigger proportion, so your art turns out bigger, it will run off the edges of the page when printed. Try it, you’ll see. So that means that for this exercise, you should reduce your art at 47%.
A few other considerations:
Remember that photocopiers can’t copy all the way to the edge of a page. They always leave some white space. The “print size” of a standard digest size mini, therefore, is not the full size of the booklet (8.5: x 5.5″), but is at least 3/8 of an inch maller on all sides. In other words, your print size for a digest mini would be, at the maximum, 7.75″ x 4.75″ You can go smaller, but you can’t go bigger, because your art won’t fit on the page.
If you want to use a “bleed”, i.e., images that run off the edge of the page, you will have to hand-trim your mini after you’ve bound it, which is a lot of work.