A while back I read a reference by Don Lancaster (guru's lair;
The reference is as follows: "Described in the August 15, 1994 issue of Design News. Take a base plate and place six ball screws or linear steppers uniformly around a circle placed on it. Now lean each ball screw in 45 degrees or so and attach them to a smaller upper head plate. The upper head plate can easily assume all of the normal lathe or mill motions. But there are no precision sliding contacts anywhere! All bearing are plain old round ones. All forces are pure tension or compression with zero side loadings."
The description is clear enough, but I've got two problems. I don't see how there is no side loading. Agreed that MOST of the force would run down the ball screws, but to say "ZERO side loadings" seems a stretch.
Second, how would this become a practicle machine? If it can assume all the lathe and mill motions, then this would be a great machine for the home/hobby shop tight on space.
I've google'd on "virtual ways" and some other terms, but can't seem to get any other infomation or a picture of what such a machine would look like, let alone any information on actually building one.
So, what am I missing here? Thoughts and references are welcome.
Thanks, Kevin