Has anyone attempted or built a vertical mill? I curantly have a momus design mill and love it, but it is way too small. I would like to build a 5x9 for 4x8 sheets. I know there will have to be counter weights on the axis. Any other problems I need to be thinking of?

Here's a pic I found on the net, looks promising.
Click image for larger version. 

Name:	greenLean-600.JPG 
Views:	0 
Size:	111.3 KB 
ID:	248420