Is this a layer shift or something more sinister?
Hello! I am new to the prusa world. Until recently the Mk3s was churning out flawless prints, and now every print has these major grooves or entire bits of the model shifted by an mm or less. Its impossible to get a straight line now!
Can someone enlighten me about what's going on?? Pls see attached pic. Thanks!
The most likely cause is that one or more of your grub screws are loose on the motor shaft. If these are not properly tightened in the correct order they WILL work loose over time. When they are slightly loose they can rotate slightly on the flat and when very loose can spin all the way around. Looking at your print I'd say the one on the X axis is loose as its moving side to side in that axis but your Y axis (bed) looks ok.
To correctly fit you must start with both loose and then tighten one against the FLAT of the motor shaft first. Once that one is properly locked down tighten the second. This acts to jam the first, locking it in place.
One other tip is that once properly done you can use a thin sharpie marker or similar to draw a line on your pully and motor shaft so that you can see if it is ever out of alignment in the future.
Yes you may be right! I will check and report... Thank you for the advise