Leo, way, WAY back, like circa 1974 we had a tour of the P.F. Avery company in southern NH. HOLY SMOKES!
They were fabricating nuclear pressure vessels for power plants out of stainless steel. The tanks were made by cutting huge rings of 4 inch thick stainless steel and then welding them together. The vessel had to be about 10 X 20 feet tall. They used these huge vertical lathes to machine them. The operator rode in a carriage alongside the cutting tool, which, IIRC was a 2 inch square shank with the biggest piece of carbide for an insert I have ever seen. The material was coming of in a ribbon and could have been used for a coil spring.
I just looked them up on line. It appears they took a serious nose dive when all the folks got upset about nuclear power and are now an itty bitty consulting firm of two people. Looks like they reorganized in the early '80s.
BTW Leo, I looked at the video of your machine. Very, very nice indeed! I am thinking that "rubber" on the bed is actually a pretty good idea, not sure what it would cost to replace it eventually, but still a good idea. When we moved down here I scrapped the base for my machine since it was cobbled up from parts of Machine #1 base. Much more rigid now. But it is still not welded steel. I like the size of the columns on your base. Stout comes to mind.
Low Profile CNC Router Vise