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I had fairly good prints until recently. Now, every print has the loops and such below. Inland PETG and Bambu PETG have the same issues. I know it is going to be some small, simple setting, but after a spool of failed prints, I'm starting to lose my mind. It is a P1P Bambu printer with a 0.8 mm nozzle and either Inland PETG or Bambu PETG. I am using a dehumidifier/drying dock running almost constantly (I live on the Texas Gulf Coast, meaning humidity). I've tried print temps from 235-255 °C and heated bed from 75-80 °C (Textured plate)).

Photo of two identical models with layers not adhering or poorly extruded

Photo of one of the printed models with poorly extruded bottom and top

Photo of a temperature tower where the underside of every bridge is drooping down

Another photo of a temperature tower where the numbers on the side are not legible due to poor extrusion

agarza
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SliderBlackrose
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2 Answers2

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If you are indeed using the base profile that tops out at 250 mm/s and an 0.8 mm nozzle, it's probably insufficient cooling combined with print speeds that are too high. You'll need more cooling than 10 % even at lower speeds with an 0.8 mm nozzle. The large extrusions have more thermal mass and tend to cool slowly. As to why it specifically makes those "loops" instead of just sagging, the filament is probably not completely melted which will cause it to curl all over the place as it comes out of the nozzle. Slow down the prints to 15-20 mm³/s at the fastest and increase cooling.

0scar
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TreeBarkEater
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Several different methods can be tried to solve this problem;

1- The type of filament you use (PETG) is a material that holds more moisture. You should definitely check your fan settings according to the region you live in.

2- I think you may have also reduced the retraction speed in the formation of the filament pile in the image. You are probably doing it to get a more uniform layer with a slow retraction, but the filament melting in the nozzle may have become leakage and formed piles at certain points.

But here especially because problems occur in the beginning and end layers;

enter image description here

3- Instead of reducing the retraction speed, you can better control the moisture content of the filament by changing the temperature between the layers. Higher temperature can vaporize the moisture in the filament and thus improve print quality.

Especially since the starting layer will cling to the ground, and act as a support structure, it can create leakage due to excessive moisture.

Büşra Fatma SUSUZ
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