<https://community.ultimaker.com/topic/14409-getting-lines-and-seperation-in-my-prints/#comment-151438>
<http://schema.org/text>
"My suspicion goes to the z-bearings. If you decouple the spindle from the bed, or at least the z-motor from the spindle, does the bed move smoothly? Without points where it feels like there's sand in the bearings? \nSuch friction points in the z-bearings can hold the bed at a certain position while printing. It just hangs there for 2-3 layers, until the play between spindle and nut runs out, so that the bed is forced past this friction point. Since it then drops multiple layers, the next layer that is printed looks underextruded, and may cause separation as you describe. "
<https://community.ultimaker.com/topic/14409-getting-lines-and-seperation-in-my-prints/>