i don't join at all.... i begin the binding strip with the end (2--3" extra) folded over itself perpendicularly...making a 45 deg fold with the end pointing at the center of the potholder/quilt....stitch all round and when you get back to the fold, move binding strip to the outside about 1/16th of an inch.... so the raw edges are a bit off the edge.... now seam down for about 2", cut off on diagonal (to prevent more bulk) and then fold the first end over, clip off extra and top stitch...looks perfect every time and the tiny 3/8--1/2" diagonal cannot come undone as it is sewn 2" inside... no wrestling, no wrong guesses.... it's easy, fast and looks perfect every time as the original 45 deg fold is all you see...