Minor update,  installed the 5/8" acme screw for the X axis using a 3/4" push bearing in the uprights.  NEMA 17 motor connected with a 6mm to 5/8" coupler. .  Z plate has 2040 openbeam installed.  Next step is to mount the Y axis acme bolt,  motor and hardware.  

This is the current state of my CNC build. The X and Y axis are complete, using 12mm Rods and bearings.  I am waiting for delivery of some 20x40mm Openbeam to start the build on the Z axis.

  The Z axis will be removable to swap different cutters/heads that can easily be bolted onto the 2040mm openbeam..  After that, the only parts that remain are the 5/8" threaded rods and the electronics.

The initial setup will be Sainsmart tb6560 4 axis 3.5amp controllers using 3x 17hs24-2104s Stepper motors and Mach3 Controller software  running on an old IBM Thinkpad (for the serial port) running WIN-XP. Not sure of the cutter head that will be used, but initially going to use a palm router with an electronic speed control unit.