I noticed that most fabric is not on the bolt straight. After washing and ironing, I try to line up the 'straight of grain'. Sometime's I end up cutting 2-3 inches off of one end just to get a straight grain of fabric. When you try to line up the fabric on the selvage edges don't go by the cut edge. Just keep working the fabric until the selvage lines up evenly and it 'hangs' right. Then cut you square up line. If all else fails pull one of your threads to get you straight of grain. If your straight of grain isn't as true as you can get it, no matter how many times you square your fabric you'll always get the dog legs. Hope this helps. Good luck. Cheryl