Thanks mhollifiel for that video....it is well worth watching...I sort of do this but tear off 16 or 17 inches then line up selvages and fold but cut the normal way. I think her way of doing it in reverse makes sense and is more accurate. i don't think I can cut 4 layers but I can certainly do 2. ....referring to site below:
https://www.youtube.com/watch?v=NoBKOv3Azzw