Originally Posted by thepolyparrot

I love these rulers, too. :)

My studio being what it is, the instructions are never with the ruler, but she keeps them on her free patterns page, down on the left side: http://www.quiltinaday.com/freepattern/

Just taking a wild guess, but at the point where you layer the HST's together, you might be lining up the seams, instead of the outside edges of the squares. That's the only thing I can think of that would make your blocks small.

If you can take pictures of your steps and how you're coming up short, maybe we can help you?