[SOLVED] Bad quality when printing PETG

I don’t think so, because even their PETG-CF profile for their filament can get better results with some additional changes. But there lies the first hint about cooling - their PETG-CF has much lower cooling values (0-30) compared to their generic PETG (40-90).

I can give some rough values I use for every PETG filament I tested so far and they all work about the same (Overture, Prusa, PolyLite, eSun):

  1. Bump up bed heating a bit, so the parts really stick (75-80) if you use textured plate.
  2. Increase nozzle temp to 265 for better layer adhesion and shiny look. Lower temps do not help for better quality, but just make the print less sturdy. I keep 1st layer at 255 to reduce oozing (because 1st layer is also slower).
  3. Main part cooling min set to 0, max to 20. Set AUX fan to 90.
  4. Set chamber fan to max (we want good ventilation around the part, but not directly on part); you do this with filament start G-code: M106 P3 S255

This should work for ANY PETG filament and massively improve quality (no more blobs that stick randomly around the part and filament strings that curl up). Overhangs are massively improved.

To even further improve quality, you can reduce speeds. Default Bambu print profiles are very fast and optimised for PLA. I am still working on that to see which speeds I should reduce, so it is good for overall any type of model. A quick change you can do is to simply reduce any speed (apart from Travel) to less than 200, set Outer wall to 100-150 and Top surface to 100-150. Generally, a 1/3 decrease compared to PLA speeds. Changing anything else has almost 0 effect on quality.

Print with open door and open lid in a cool room.

Let me know how that works for you. These changes made the biggest improvement.

24 Likes