Horizontal lines on walls

Warning: I am new to 3D printing! I got the P1P about 5 weeks ago and the AMS 3 weeks later. I have run about 3kg of mostly PLA and a bit PETG filament through it and had no failed print or other worries. I thought I was happy but…

The more I print the more I struggle with how walls look like.

I have been printing a few cases for NodeMCU applications and found that vertical walls look a bit like linen. It’s most apparent with white Sunlu PLA+, less visible with black and and blue and least (but still there) with red from the same manufacturer. The issue is horizontal lines of variable thickness as shown in the photos. There is nothing on the inside, which could cause this. The only way to influence it seems to be the number of wall loops (large casing with 4 wall loops, smaller sample with 3).

What I have checked but made no difference

  • Place printer on floor instead of table (firm basis)
  • Temperature fluctuations of nozzle and bed → within 1degC of target
  • Nozzle temperature → from 210 to 250degC
  • Max flow volumetric speed → down to 10
  • Overall print speed → down to 30m/s
  • Print outer wall, inner wall and wall infill at the same speed
  • Extrusion calibration (0.025 white, 0.02 read & blue Sunlu PLA+) → varied from 0.015 to 0.045
  • 1st layer height set to have an integer ratio of remaining model height and 0.2mm layer thickness
  • Hot bed tramming
  • Removing/reattaching the z-axis belt
  • AMS vs single spool

There is a visible hotbed curvature (trough in the center - maybe 1mm?) and I will open a ticket. But I doubt, that this is causing these lines.

What else could cause this? Should I try different filament brands? Or is the result perfectly normal? I have some prints that look much better (chute bin with thin walls) while others look awful (armor mod plate).

I have a X1C with the same problem. Calls opens weeks ago. Until now no working solution found. Already play removed in the head, Speed, increases temperature, changes Flow. Z spindles cleaned etc. nothingness helped.

Some possibilities:

@millenniumpilot I’m “glad” I’m not the only one. Will be very interesting how your support ticket will turn out.

@msinger From the link you provided I guess I can rule out temperature fluctuations. Extrusion due to bad filament is a possibility. I did buy the Sunlu because they claim a tight diameter tolerance. But their white filament performing worse than the red makes be believe it could be a filament issue. Tomorrow I will receive a spool from another manufacturer… will report here, if it helps. I have no idea how to check for mechanical issues. At least nothing feels loose…

White is always problematic - it is pronouncing the normal downsides of FDM really strong.

I have the same „issue“, but stronger than on my vorons. I blame partially the extruder from the X1C.

Disabling arachne helps to reduce it a bit.

i had some of that a couple months back when i got my first P1P, it printed good then started going off the rails so to speak, not long after there was a update for the firmware, i did that…then i ran calibration on the printer and then did a Cali and choose the best looking line i could see and be great ever sense, if you have the newest firmware try doing both, it worked for me, when prints start looking off even on my 1XC i do a calibration, the 1XC has lidar and checks the test layer before printing so no cali to run…

one other note… if prints are looking off, make sure your nozzle is clear and clean, one of my 1XC was starting to print terrible, i tried to clean the nozzle and notice it was starting to plug up so i changed it problem was solve…i almost bet it a nozzle or needs a calibration and cali run… hope one of these tips get you back on track

nozzle is clean and calibration with lidar and manuall cali is without sucsess.
Filament is babulab basic pla in different colors, not only white. After reducing speed, it is a litle better.
I also blame partially the extruder from the X1C. Bambulab has sending me a new one, but not testet yet.
Greetings from Germany.


I made a small test cube: 1 wall, no infill
Indeed there is an extruder pattern - this pattern will change to non-pattern when infill is applied or other shapes are within the model.

I will play around with the extruder tension. From my experience this shows usually up because of bad gears or too much tension.

€: I can confirm loosening the extruder gear tensions mitigates the issue:

Left before, right after:


That looks pretty convincing! So I will drill that hole and try the same.

@rovster May I ask how much (full 360degree) turns of the screw were required to achieve the result you’ve shown above? And now the silly bit… in which direction did you turn? At first I thought about counter-clockwise to loose the screw, but looking at this photo I wonder if tightening the screw would pull the string away from the extruder.

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I checked several positions, I noticed that loosening the screw (counter-clockwise) more than flush to housing doesn’t have an impact anymore.

Hope this helps you. :slight_smile:

E: Just saw the picture you mentioned, might be possible that tightening the screw could pull the gear more away from the other. Honestly not sure… will test. :slight_smile:

I loosened by two full turns - without improvement. I went back and tried further clockwise, but the screw could hardly be tightened more. So I went back 2 turns and a third… The screw head slightly pushes the casing outwards. If this is still not enough I either need to drill a bigger hole or it’s a different issue.

Might be possible that this screw is too long and therefore It can’t be more tightened to pull the hears more away from each other…

Found this video by Bambu Lab: click

Loosening the screw offloads the spring. Unfortunately, this seems not to solve my horizontal line issue. I unscrewed it until the head was sticking out of the hole and the result is as before :frowning_face:

Disassemble the hot end and check all gears and motor shaft are machines and turning uniformly. If any one of them has a hole not centred or the motor shaft is spinning with an angle. It could cause inconsistent extrusion like this

I have replaced the complete hotend and the extruder. Print quality has improved but the issue is still there. I would say half of the gap to perfection has been closed. I checked the old extruder and found nothing suspicious.

I also have yesterday replaced the extruder. Print quality not improved. I am sad.

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I think, I have make a litle mistake. After replacing extruder, i restore all other settings to default.
That was wrong.
Yesterday i print several other testprints. New extruder and reducing flow ration from 0,98 to 0,90 and change order of wall to “outer, inner, infill” and reducing max volumetric speed for generic PLA from 12 to 10 (bambulab basic pla remain constant to 21) and increase nozle-temperature to 230°C may help.
I will make other testprints, but i believe, changing the settings combined with the new extruder gave me good prints!
This all together without new extruder has not helping!

I have tested your settings and I believe that the important parameter is the wall order. With outer wall first the outer wall’s quality improves substantially (not perfect though) but the inner wall degrades. Looking at my older tests with inner wall first, the inner walls look as good as the outer walls now. Reducing flow ratio simply resultes in thinner prints w/o impact on the wall smoothness.

flow ratio should only be adjusted to to avoid under- / overextrusion. Otherwise it will result in squish (overextrusion) or thinner lines which may not well connected with other lines.