Bfb 3D Touch Set Up And Operation Manual page 26

3D Touch
During each movement along the side of the bed, observe from the side of the machine any change in distance between the bed and
extruder's hot-end as it moves along.
Adjust the height of the bed bolts to make each side level using the 3mm hex driver from the toolkit.
Underneath each of the 3 bed bolts is a locking nut which must be loosened with the 8mm spanner before the bolt can be adjusted.
It may take several movements of the extruder, and consequent bolt adjustments to ensure that the bed is level.
Ensure that axes are checked from the appropriate side of the machine (to better judge flatness):
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