Strange, I use mine with regular 8.5 x 11 printer paper printed at 100% and it fits fine. The scale on the printed protractor measures precisely with a ruler. The toughest part of using this protractor is accurately cutting the spindle hole. I have been using the method proposed on the vacuumstate protractor with great results.
Basically, draw a 90 degree triangle around the center dot so that each side is tangent with the dot. Then use a utility knife to cut the two sides that meet the 90 degree angle, and fold the paper back at the hypotenuse. Now the hold is actually a triangle, but fits perfectly and snugly where it should be.
Basically, draw a 90 degree triangle around the center dot so that each side is tangent with the dot. Then use a utility knife to cut the two sides that meet the 90 degree angle, and fold the paper back at the hypotenuse. Now the hold is actually a triangle, but fits perfectly and snugly where it should be.