To read Part 1, go here.
So after you've sewn your diagonal line, open it up and line it up to the side of your quilt, to make sure it's the right length.
Looks like we're good to go! Trim away the excess fabric and sew down the gap. You're all done with the machine sewing part now. :)
When trimming away the excess batting, I used to cut right to the edge of the binding. A friend explained that doing it that way creates less-than-full bindings and can knock of points if you're showing your quilt.
To make the binding more fuller, you need to cut half an inch away from the edge of the quilt/binding. This half an inch number only works for 2.5" bindings. If you have a 2" binding, I think you need to cut only a quarter-inch away from the edge.
I trim half an inch from the binding all around the quilt.
To prevent bulky corners, you need cut it away at a 45* degree angle.
To read Part 3, go here.