This is a weird one...
Same printer, same settings.
Differences : Material PLA printed at 215/60. The other material is XT printed at 260/75
Using PLA there is no problem at all, prints up to 9 hours. Beautiful prints, very nice and flat perimeter with no issues(ripples) at all. Every time again.
Using XT : Prints nice to but suddenly shifting in Z direction every time again. No particular distance, shifting is never the same amount. It jumps from 1 to about 6 mm.
Several tests first PLA then XT, every time again, same result.
It's obvious it has nothing to do with the material itself. It is temperature related, but what is the problem...?
Meanwhile already change 10 times filament.
Meaning alternately same object printed 5 times with PLA and 5 times using XT.
Every single time bed-shifting when printing with XT filament. NO problem with PLA at all.