Susan Carlson Fabric Collage: Top Tip—Take the Wheel, the Proportion Wheel, as Your Friend

An important step in creating your fabric collage is deciding how big the final piece should be. After you draw the smaller line drawing of your subject, you’ll need to figure out the percentage for your enlargement.

For example let’s say the pattern of your subject is ten inches in height and your want the final image to be thirty inches in height. That’s an easy one, right? Right? Right.

The enlargement percentage in this example would be 300%. But most of the time the math doesn’t math as easy as that.

Top Tip:

If math isn’t your friend, a proportion wheel can be.

Let’s say a student’s subject is a portrait, a good rule-of-thumb is to enlarge a design to the proportion where the eye of the subject is 2 inches or so in length. Eyes have a lot of detail in them so you want them large enough to be able to create that detail without driving yourself crazy.

So what if the eye measure on the initial drawing is 3/8ths of an inch? To get the enlargement to two inches, what’s the percentage for that?

Well, you can definitely use math to figure that out—my husband Tom, likes to take that tactic. However, since math and I have a respectful but distant relationship, my tool of choice is a proportion wheel (or scale).

I first ran into a proportion wheel in the graphic design classes of my college days and have been using it here and there ever since. It’s a handy tool to know how to use. The way a proportion wheel works is by matching an original measurement on the inner wheel and lining it up with your desired measurement on the outer wheel. Then you check the little window in the center for the enlargement percentage.

Here’s an example: Let’s take a look at a cropped version of my tripod pup Felix, from the photo above.

I’ve traced the photo onto an 8-1/2″ x 11″ piece of tracing paper. His eye on our left measures 7/8″ from side-to-side, as marked on the drawing detail below.

I’d like to enlarge the 7/8″ eye to the optimal 2″. I line up the 7/8″mark on the inner circle of my wheel—size of original—to the 2″ mark on the outer circle of my wheel. The percentage of original size, 230%, now shows through the cutout window—pointed at by the pencil, above—is the enlargement percentage for my drawing.

Keeping the inner and outer circles positioned as they are, I can now check to see what dimensions other aspects of my drawing will enlarge to. For instance, Felix’s side-to-side width in the original drawing is 8″. So if I find the 8″ measurement on the inner wheel, I can see that it lines up with the 18″ mark on the outer circle, the reproduction size.

In the same way, without moving the wheels from the 230% mark, I can see that the measurement of 10″ from the top of Felix’s head to where I cropped his body in original drawing, converts to 23″ top-to-bottom in the reproduction size. A 1-1/2″ nose enlarges to 3-1/2″, a 1/2″ tooth to 1-1/8″, and so on. It could be never ending fun. 😉

These particular calculations mean that with a 230% enlargement of my small drawing, I’ll have an 18-1/2″ by 23″ design for my collage of Felix. If that feels too large or small for me, I can keep adjusting and playing with my proportional wheel for alternative computations. My math buddy could become my best buddy.

Top Tip:

If math isn’t your friend, a proportion wheel can be.

For further information, see this post: Enlarging a Pattern for Fabric Collage: How to Do It at Home Online, first posted July 20, 2024. Among other tips, it features the short video below, giving another example of using a proportion wheel.