I like this build, and that the author uses OpenRail with V-bar, or T-bar. Its pretty straight forward build and incorporates some bits of Shapeoko too. My 2 cents….not sure if I would build this, its running the author around $2G to build. I think I could pickup a used shopbot and retrofit that.
http://www.instructables.com/id/Customizable-and-Autonomous-CNC-machine/