A proportional scale is a handy tool to use when you want to figure out how much bigger to make a design drawing or pattern to fit where you want. It is a sliding scale with two wheels. The inner, smaller one gives the sizes of your starting drawing. The outer, larger wheel provides the comparable larger sizes of the drawing you want.
For instance, start with a drawing that is 8″ x 12″ and you know that you want to make it into a drawing 35″ wide instead of 8″. How big overall will the drawing be? Find 8″ on the inner wheel. Rotate the outer wheel until 35″ is directly above the 8″ mark. First, look over in the window to see the calculated percentage increase of 440%. You can then look at 12″ on the inner wheel and see that 53″ lies directly above it. Your final drawing will be enlarged 440% and will be 35″ x 53″.
This summary is taken from Design Explorations for the Creative Quilter by Katie Pasquini Masopust.
From The Tech Editors