Z-Banding, Overextrusion, Layer Shift? Outer Layer Imperfections

Bambu Lab A1 Series Troubleshooting
1

Hello everyone,

I’m at a complete loss here. These Layer Shifts right here:

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I’m using a Bambu Lab A1 with a 0.2 Nozzle, using my Custom Settings. (These didn’t cause any issues before) I’m not sure when the issue popped up, but no matter what I do, I can’t seem to get rid of it. To make matters worse, I’m getting some contradictory results. For example, it always occurs around the same Layers, which leads me to believe that it might be a mechanical issue. But when using a different Filament, the Imperfections aren’t nearly as bad:

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Still visible, but not even close to the other picture…Which leads me to believe that it might be an issue with the Filament / Extrusion?

I have tried:

  1. Re-tramming and re-calibrating the Bed.

  2. Increasing / Decreasing the Flow Ratio slightly.

  3. Greasing the Z-Axis

  4. Drying the Filament

  5. Printing at a different Temperature

I ran several Flow Rate Tests and First Layer Adhesion Tests to check for potential extrusion issues, but they seem to be fine.

It doesn’t happen at the same height, so say if Model A has these imperfections around 5cm, Model B might have them at 6cm. Some times they don’t have the imperfections at all, but when they do, it is reproduceable and occurs at the same Layer Height.

Lastly, usually the issue isn’t as extreme as shown here. Some times it’s just a single shifted Layer, and the rest of the Print is perfect:

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Switching from Arachne to Classic reduces the issue, but won’t get rid of it entirely either:

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I’ve been printing without any flaws so far, and at this point I’m running out of ideas.

Taking a closer look at it in the Slicer, it seems it might be related to the Flow Rate:

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Whenever there is a shift in the volumetric flow rate, the imperfections seem to occur.

2

I was getting some minor issues popping up like this as well the banding so I did a once over*

On the mini here I just did some maintenance and noticed the 2 of 3 screws behind my hotend were starting to work lose I could tighten them a good 1/8th turn.

Maybe run through the belt stuff as well for a full refresh everything if the flows and filaments seem alright (they do those are good prints besides the errors here)

I think for the A1 it’s this → A1 Belt Tensioning | Bambu Lab Wiki

EDIT: this is what I was looking for. you don’t need to rip it all apart. look at step 4, there are 3-4 black tiny screws not their green ones, but check them all. Basically do a once over and tighten the ship!

edit2: once done don’t forget to do the full long machine calibration from the settings menu!!