Once in a while on here someone will tell a quilting story and it will include the phrase "...and then I found out my ruler was 1/16" off! Grrrr" or something to that effect.
I'm just curious. How do you end up figuring out that your ruler is off? Do you take another ruler and compare (if so, how do you know the other ruler isn't off)? Is there some sort of calibration device to check? Nobody has explained how they ended up figuring out that their rulers were off and therefore their measurements were off.