I would highly recommend looking at 45's 2005 robot if you can find some pics. It was a very unique and elegant design solution to a turreted arm. The "turret" part of it was not at the base. They had tower structure with a shaft inside some bearings. The "shoulder" joint was at the top of the shaft. I was impressed, but then it IS the Technokats after all!
Matt B.
http://www.chiefdelphi.com/media/photos/21868