What is creating these ugly effects?

Bambu Lab P Series Troubleshooting
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Printer: P1S with AMS

Filament: Elegoo Matte PLA Black (calibrated in Bambu Slicer)

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For some reason my prints come out with weird surfaces and corners like this:

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IMG_08191920Ă—2560 748 KB

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IMG_08221920Ă—2560 725 KB

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IMG_08201920Ă—2560 403 KB

I am using the 0,2mm Standard setting and have only changed top surface line width to 0,32 and top surface speed to 30 mm/s and the surface patterns to Monotonic Line. These settings usually create perfect smooth surfaces with almost invisible layer lines. The only settings I’m not sure about are the temperature and cooling settings. I have disabled cooling by the aux fan completely for PLA and set the pet fan to 60% for both. Temperature for nozzle at 215 degrees C. Could either of those be the problem? Does anybody have any idea what could be causing this? Filament is dry. I am quite new to the hobby and have no clue what could be causing this… ;(

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These are not defects typically associated with wet filament. Moisture usually produces random bubbles, pits, popping, or rough surface texture. What I see here is more consistent with inconsistent extrusion or poor pressure control.

Before changing calibration values, verify that the filament path is not binding. Check the spool, PTFE tubes, extruder gears, and nozzle for excessive resistance, wear, debris, or a partial blockage.

I would then calibrate in this order:

  1. Nozzle temperature
  2. Flow ratio
  3. Pressure advance

The example below appears to show inconsistent extrusion. I would first perform a first-layer test using a cube primitive sized to 200 Ă— 200 mm, with the height set equal to your actual first-layer height. For example, use 200 Ă— 200 Ă— 0.20 mm when printing with a 0.20 mm first layer.

Random blotches or isolated areas that fail to adhere may indicate build-plate contamination. Uniform gaps between adjacent lines may indicate underextrusion or excessive nozzle height. Repeating bands can indicate inconsistent extrusion, bed-mesh variation, or resistance in the filament path, so banding alone does not conclusively prove that the flow ratio is incorrect.

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image1705Ă—1089 153 KB

After temperature and flow ratio are calibrated, move on to pressure advance. Pressure advance compensates for the delay between extruder movement and pressure changes inside the nozzle during acceleration, deceleration, and direction changes.

Pressure advance that is too low commonly produces swollen corners and excess material. Pressure advance that is too high can produce thin sections, gaps, or underextrusion immediately before and after corners. The corner defect shown below could therefore involve pressure advance, although seam placement, retraction, acceleration, or inconsistent filament feeding may also contribute.

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image1683Ă—1020 107 KB

1 Like
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I do the flow rate and flow dynamics calibration with every single filament I buy. weird thing is, K factor is almost always the same: either 0,015 or 0,020 (default)… Flow ratio also has very similar values for most filaments, most of the time its 1,0187… It seems that the “Generic PLA” has the best print quality, which sounds just wrong? I’m struggling with temperature calibration tbh, it is extremely imprecise (for me) and hard to figure out…

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Oh, also, this issue does seem to only occur on the left hand side of the bed…