I just got one too. The way I see it, is that if you want the circle to be larger than 36 inches, you have to add to the side with the 18 inch mark. Just extend the sides., or tape a piece of card stock on and draw the same increments as you have. This will make it wider at the outside and you'll have a bigger circle. The 3 inch mark is where the hole will be. For a 36 inch circle your strata only has to be 15 1/2 inches wide. The width of your wedge ruler.(if your strips go straight up and down. If you want to angle your strips, then you have to have a wider strata. you'll
You'll have a 6 inch diameter hole with 15 inch of material on each side for a total of 36 inch.