121- Proportional Scale

Please excuse me if you are seeing a second copy of this post. I’ve been doing some website revisions, so this post might get replicated!

Last post I casually said I use my full-size drawing to determine what size enlargement I will need to make my photocopy. Copiers need to have a percentage number – but how do you figure that out? For that, I use a proportion wheel. It’s an absolutely essential tool!

Rotating the two disks until actual size and intended size match up will result in the percentage size difference. The numbers on the disks refer to inches, but that does not matter as long as before and after size are the same type of unit – millimeters, graph paper squares, etc. I have a three sided Koh-I-Noor engineer’s ruler with measurements in inches, mm, and different scales (1/4”, 3/8”, ½, ¾”) that I use along with the wheel. I use the side of the ruler that matches up best with the thing that I’m measuring and keeps the numbers as whole numbers – I find that easier than dealing with inch fractions.

I started using a proportion wheel as a graphic designer. No computers, so changing size of graphics needed photographic reproduction, sometimes requiring a courier to pick up and deliver originals and copies. An error in size specification could cause a major delay in production!

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