With the tool from Missouri Star you sew your binding all the way around the quilt and leave a 12 inch place on one side. You should leave 10 inches of binding on each side of this 12 inches. You cut the binding on the Left along the angle on the ruler. You take the ruler and turn it the opposite direction on the Right and cut it going the opposite way. Flip the ruler from one side to the other. The updated tute on Uptube is very clear. Scroll down to the last tute.