Hi all, I have an issue when printing small details on a spaceship model I’m printing. In various places on the printed parts the printer creates either grooves or ridges in the horizontal plane directly after some form of small detail is printed. I have included a picture of the printed part (lines1.png), the 3D model topology in Bambu Studio (lines2.png) and what the area looks like when sliced (lines3.png) and just the layer where the lowest of the small details starts and where it looks like the issue occurs (lines4.png).
Initially I thought this could be because of low pressure in the nozzle after small retractions after small areas of gap fill, but in the example picture lines4.png all the printed lines in the layers where the issue occurs are continues even width lines, there are no gap fill areas. It almost looks like the printer doesn’t want to extrude material after having extruded the detail part.
Also I notice there is a small overhang wall (blue) on most of the details, but this issue occurs regardless of this as can be seem in the bottom one of the small details which doesn’t have the overhanging wall.
Printer: P1S
Material: Bambu Lab Gray PLA
Nozzle size: 0.4mm
Layer height: 0.12mm
Line width outer wall: 0.42mm
Line width inner wall: 0.45mm
Outer wall speed: 60
Wall order: inner/outer
Wall generator: Classic
What I tried to resolve this is:
- Calibrated the material and flowrate for this PLA.
- Tried printing at 0.2mm layer height. Same issue, though less pronounced for some reason (!).
What I haven’t tried:
- Using Arachne for wall generation as in this example with these continuous even lines I don’t think it would matter?
Does anyone have any idea how I can resolve this?
No one has any idea why those horizontal lines are in those parts of my print?
As a test I tried printing a small section of the model with arachne, but the issue persists (see photo).
I didn’t take a photo, but I also tried printing outer walls first but it also doesn’t help.
I’m kind of at a loss here. If the issue was somehow Z-axis related (I had that once on my old Ender 3) the lines would be going all around the printed part, but they are3 clearly not. Somehow they are related to the bump detail that preceded them during printing but I can’t put m finger on why this is happening.
Ok, I did some experimenting and printed a bunch of XYZ calibration cubes with extruded letters (to create overhangs) to try different settings and speeds. I seem to have mostly fixed the issue.
Settings to change::
QUALITY tab >
- Precision > “Precise wall”: Enable
- Advanced > “Detect overhang walls”: Disable
Analysis:
The issue I presume was that because the printer slowed down when printing an overhanging wall, and thus lowered extrusion rate, didn’t pick up a higher extrusion rate when it finished the overhang thus basically not extruding enough material beyond the overhanging wall, creating what appears as a groove in the print. Disabling “Detect overhang walls” makes the printer not slow down when printing an overhang wall and seems to keep the extrusion rate at a (more) constant rate. This seems to mostly solve the problem I had.
I also enabled “precise walls” because it seems to make the walls overall just a bit more coherent in appearance.
Caveat:
The problem looks to be completely fixed when printing in 0.2mm layer height. But in 0.12mm layer height the issue is still (barely) noticeable. It’s good enough for me though.
See the attached photo for my 0.2mm and .012 mm final test prints.
