There's a way to make HSTs I like better... put your square pairs right sides together. Sew all around the perimeter with a 1/4" seam allowance. Then cut diagonally both ways, and voila! Just because I'm lazy, I usually start with 5" squares from a charm pack, but you don't have to... you can cut your squares any size, depending on what size HSTs you need to come out with. This method eliminates the two diagonal seams, and the HSTs seem to be more stable (less stretchy). Your quarter-inch foot should be more than adequate for this method.