Here's a pic of one of these mills , they pop up forsale over here from time to time .
As far as I've been able to find out they were made up to mill 8'6" .
If you look at the pic you'll see how it works .
This one has been mounted on an axle .
Thanks for the pic. That would be pretty easy to make once you've seen it. I'm gonna do a search and see if I can find some video of one in action, Joe.