Wow, I'm having a hard time describing this. Pretend you're hand-quilting a circle. We all know how much fun that is, especially in a floor frame!!
I don't make a knot but pull 1/2 of the thread at the top of the circle then quilt down one side until it becomes uncomfortable, then start again at the top and quilt down the other side. It's a big time and thread saver. And I hope that makes sense!!!