Y-axis issues (x-axis length??)
I've been having trouble with my MK3S since I assembled it. At first I couldnt get the initial calibration to work because I was getting "X-axis length" issues. After a factory reset it worked for a while then it seemed to lose track of where the Y-axis was. Prints would still work but they'd be to far forward/backward on the bed. After some more factory resets and calibrations the problem went away again. Sometimes it takes a few factory resets and re-calibrations to get it working again. I'm on my 3rd reset cycle so I've pretty solidly confirmed at this point that it isnt a fluke.When this happens one of my symptoms is I can turn the printer on and try to manually move the y-axis with the settings/knob but it will stop short in one direction and try to go too far in the other.
RE: Y-axis issues (x-axis length??)
Power your machine off and move X and Y by hand in both directions.
If you find a direction that "binds" - you have a bearing problem.
Either you did not lubricate your bearings or you installed them too tightly. Those U clamps are especially prone to this.
Also look for and zip ties or cables getting hit during traversal. That will cause similar problems.
RE: Y-axis issues (x-axis length??)
@robert-rmm200
We had a similar problem. The fix was to move the two linear bearings for the smooth rods on the y-axis plate as close together as possible.
After 3 days of successful (and beautiful) prints, we started getting y-axis errors. After a 12 hour chat session with customer service we "fixed" the problem after going all the specs on the printer. It was a good learning experience and a real PIA.
The fix was caused by one of two different issues. 1) we removed the heating bed and loosened the u-bolts on the dual linear axis side of the y-axis frame. I then moved the y-axis by hand to the extremes, which pushed the two linear bearing as close together in the frame cutouts as possible. I then tightened the u-bolts securing the bearings. 2) We also noticed that the thermister wire (black wire) had moved to the outside of the little risers that lift the heated bed off the y-axis frame. We ensured the wire ran inside the riser. This latter point probably is not ususal.
After re-assembly the y-length error was gone.
The point, as told to us by customer service, is that the linear bearings provide the stops for either end of the y-axis travel. If they shift (which is possible after 3 days of printing), the new position can cause a y-axis length error.
Newbie here (1 week printing experience), but this worked.
Good luck!