what I do to keep my squares squared is I tape and hot glue both ends of a 12 inch metal ruler to the middle of my cutting board fallowing the grid lines. Then measure from the back side of the ruler the size of the quilt square and tape a 2 inch strip of heavy cardboard fallowing the grid lines. To use this quilting jig: slip the strip of fabric under the metal ruler and line the edge up with the card board strip then press down in the center of the metal ruler and cut the square. It is kind of like using a paper cutter. I also made a jig like this for cuting triangles.