Don,
If you can stand my monotone voice and watching paint dry, here is a vid of my prototype in action, the second cutting sequence shows how easy left hand threading really is. LH threading starts at about 3 mins 10 secs. Where this method scores is that you put the next cut on as it is running back to the start.
http://www.youtube.com/watch?v=8JFdNaBD5GM
John
