I posted this before but it is such a great method. For 2 1/2 inch HST cut two fabric squares 6 inchs. For 3 1/2 cut the squares 8 inchs. You can see that each size is a 2 inch difference. Then you draw an x from the corners. Sew 1/4 inch on each side of the lines. Press to set stitchs then measure in from both sides half of the square (for 6 inch sq it is 3 in) and cut in half both ways + . Dont move block, now cut on the drawn lines and you will have 8 HST. Use the Quilt in a Day trianle square up ruler if you only want to make one cut to square up. Otherwise square up as usual. With the ruler you lay the ruler line on the stitch line before opening the block and make one cut. Perfect HST every time.