Getting a 1/4" seam right is akin to passing your first driving test! Lots of practice needed. Two suggestions: (1) get another 1/4" foot that has an attached bar that helps feed the fabric; and, (2) try sewing two rectangles together, press, and measure to see if the width is actually 2 times - 1/2". You'll be surprised how many times it won't be correct. Practice! and, good luck!