Flashforge Creator Dual Z Axis loose

[shingabiss]

On my Flashforge Creator Pro Dual, the top end of the Z axis lead screw is loose and wobbling around. There is a circular sleeve above it that seems like it's where it should be located. Anyone else have this problem?

On my Makerbot Replicator 2, there is on end bearing at all on the top of the Z axis lead screw, weird.

[natewin]

The top of that should be free, constraining it with a bearing could translate into steps in your part. If there is any run-out in your z-axis lead screw the top being free will allow it to move and not affect your part. The tube at the top basically keeps you from bending the z-axis screw accidently. Some people and printer manufacturers actually leave the screws for the Z lead screw bearing (the one in the middle of the build plate) slightly loose to prevent any defects in the part. The Z axis should only be constrained by the 10mm guide rods and bearings to either side of the lead screw.