Hi, I got an ender 3 max earlier this year to help with my university projects and so far its worked perfectly fine. I added the CR-touch kit so that I didn’t have to manually level and I’ve got the z-offset dialled in, and it’s produced some excellent prints.

But recently I’ve had to do some rather long prints – around 27-30hrs. The first one had a Y-axis shift of about 1.5mm with about 40mins to go, nothing major and it wasn’t detrimental to the overall print but still annoying (picture attached). I double checked belt tension and tightened the grub screws on the pulley and went about printing some other things with no issues.

Then I did a ~31hr print and for whatever reason, about 2/3 through a massive x-axis layer shift occurs – it actually maxed out the x-axis travel on the printer to achieve it. This all happened overnight so I didn’t get to see it printing like this, or see anything that could have started it, but I’m at a loss because I can’t figure out why it would do this. The x-axis pulley is push-fit, so no grub screws to tighten, the belt is tight and there’s no sign of an issue with the print on the layers prior to the shift.

Any ideas?

It makes me wonder if there’s a setting that exists, or could be added that makes the printer re-home its x and y axes at either time or layer intervals during a long print?

Images here: https://imgur.com/a/zeSSCJ6