🚀 go-pugleaf

There exist CMM machines on a smaller scale - these are 3-D digitizers
capable of 1/10 mil accuracies. Large room size gantry robots have
also been built. Sandia Labs has one. There isn't any reason an
exising crane rail system couldn't be used. 

There are many large metal-working machines that have the kinds of
distances and sizes you need. Large horizontal boring machines,
planers etc are found in many older factories and could be retrofitted
for your use.

Chopping guns don't sound very accurate! A friend of mine is
rebuilding a large planar to hold multiple bridgeport heads and
adding DRO's for positioning - This will allow him to face and mill
very large metal pieces very accurately. The design and construction
of this is a fraction of the cost of a new machine capable of handling
these large pieces too.

There are large X-Y platforms built for all kinds of things. I've seen
one used as a large router for stress-skin house panels that works
very well. (I thinkit was featured on This Old House or something)

Making your 'urethane/metalic matrix bonded to stainless' sounds
pretty tricky - stainless is not easy to machine and is pretty costly.
Machine ways are usually cast and then milled - light lubrication
and they'll last for many decades with high accuracy. Welding
stainless is even worse.

				nivek

Kevin Dowling
Robotics Institute
Carnegie Mellon University
Pittsburgh, PA 15213
x(412) 268-8830