Waiting on an aluminum block to press my Z-Axis rods/rails into. The rods are a hefty 12mm diameter optical railing. I will have to mount the filament reels in another location vs the top of the Z, however convenient it was to have it there.

Printrbot has a very specific aluminum block that is used to support the Z-Rods.

Problems I may encounter are Z-sway and Z-torsion. Sway may come as a product of bed movement, even with the spiffy frame I built. Z-torsion or twisting of the Z-axis rods as a unit, can be a result of bed movement and possibly torque of the extruder motor.