The Orginal Z-Axis Support can be adjustet with the normal screw nut. With a trapezoidal thread this is not possible. The endsupport at the top can not be adjusted with the spindel in place. This design ist much stronger and the Screw to fix the Bracket is accessible with the spindel in place, so you can adjust thr upper bearing to unload the stepper Motor. The new Version V1 with a diameter of 22.1 mm should fit perfect with a 608 Ball bearing. This is a makeover from 3DFranky's K8200 Z-Endsupport (http://www.thingiverse.com/thing:175137) I was not satisfied with the original design. Additional i added a piece for mounting an endstop-switch.