According to the book The Quilter's Ultimate Visual Guide: From A to Z-Hundreds of Tips and Techniques for Successful Quiltmaking (A Rodale quilt book) by Ellen Pahl "The lines have to be marked at a 45 degree angle to the vertical and horizontal lines of a quilt to have a true cross- hatching design." Read Scross Hatching on this page in the book
http://books.google.com/books?id=MQn...0angle&f=false (you have to scroll down to the bottom of page 190 for the info) ;)