Strange X & Y offset when printing simple 2 perimeter part
This is on my MK3S, running firmware 3.9.0 RC1. I posted about this exact same issue on Github, and replicated it over here, hoping someone might know about or have an answer for this.
While printing a pretty simple part, I've found a strange X/Y offset on seemingly random groupings of layers. Part was sliced in PrusaSlicer 2.2.0. .3mf and gcode attached.
When the error happens, a number of layers will be slightly offset toward the center of the part. After a somewhat random number of these layers the expected printing returns. You can see the visual negative groove on the part's outside and the positive on the inside. I thought it maybe was the slicer's fault, but when checking the gocde on a simulator, the tool paths look as expected.
The grooves reproduce the same way, run after run of the same gcode. I have printed a nest of 22 of these parts, and while some parts print with the same groove defect, others have different grooves, at different Z heights.
One part with the grooves
You can see the grooves are an offset in the perimeter thru this triangular window on the back side of the part:
Tool paths look as expected:
Gcode and .3mf
5cm_Groove_Troubleshooting
The outer walls of this part should be a smooth, continuous surface.
-Steve
RE: Strange X & Y offset when printing simple 2 perimeter part
Perhaps another clue from watching how the printer is building the part. Keep in mind this part is designed to have a wall thickness of only 2 perimeters. When the part builds as expected, the printer starts on the right, lays down what I would call the inner perimeter, then continues on from left back to right with the outer perimeter.
When the groove happens, the printer starts on the left, lays down the outer perimeter, then continues on from right to left with the inner perimeter.