Creality Ender 3 Y axis clearance adjuster

This is the attempt to get a better Y-axis guide for the creality ender 3. I converted from four to only three bearings and made the clearance easily adjustable (no need for the excenter adjustment).

I guess one of the reasons for a high wear of the Y-axis rolls is that four bearings are used (instead of 3 which would be more self-stabilizing).

you need further:
- a sufficiently long M8 screw (for the actual adjustment)
- two sufficiently long M5 screws
- two M5 self-stopping nuts
- tw