That was what I assumed the reason would be, but 20,000 is a hell of a
lot of rods to join! Ask around and you might find a machine which
doesn't need modifying. I've seen machines designed to butt weld metal
strips, rather like a giant band saw blade welder. I think they called
them "rim welders", but only because they were on a wheel production
line. I don't know there proper name.

Chris.