Hi again Pete, and Hood, welcome.
I machine everything, ceramics, steel, nickel, you name it. I needed stiffness! The uprights are hollow, of course. But there is no vibration in this puppy! I can also get the head down at least as far as Shoptasks bridge. Now if only I could find someone who has used Mach3 with the Shoptask (TMG) CNC system!
turboman