Adjustable Z top mount

A number of things can get the Geeetech i3 Pro B frame out of alignment, and for me it was the tension from the x axis belt which twisted the z axis screw and guide.
You can solve those problem in other ways, but I found that an adjustable z top mount was the simplest.
You probably only need this on one side, but I made two just because it looked good :)

Included is a version similar to the original part, and one version for a 608zz ball bearing, reducing friction from the spinning screw.
The ball bearing is a tight fit (I used a small vise to push it in), but there is also a hole for an M3 lock screw just in case.

The base plate and the mount are held together by a 12 mm M3 hex screw and lock nut. Washers on both sides.

Based on the very accurate part made by Pietrogramma.

Update 160913:
Added Sketchup model.

Update 160919:
Added flipped versions of the base plate (v2), which allows better prints.