Originally Posted by Sadiemae
You can make your beginning squares slightly larger and then square up your finished half square triangle if you can't get the perfect seam allowance.
I have the best result doing this, but if I really want to do it right and not square up after, I mark down the center of the diagonal, mark 1/4 inch either side then sew just inside the line, not right on it. this allows for the thickness of the fold and any thickness taken up by the size of your pencil when marking. Gee, after saying all that, no wonder I cut bigger then square up! :!: