Fragmentation and stringing issues

Bambu Lab H2 Series Troubleshooting
1

Hi Everyone,

I’m a seasoned 3D print enthusiast who upgraded to an H2S from a P1S after two years of solid use.

I have been facing challenges right from the onset in terms of fragments and stringing and am yet to be able to print anything successfully. Below is a recap of the current situation:

  • Using official Bambu PETG filament, dried and working perfectly on the P1S.
  • Carried out flow dynamics and flow rate calibration.
  • Using default print settings.
  • Printing a simple part results in fragments or stringing - I’ve attached couple of photos for reference.

Any guidance or help would be really appreciated as I’ve run out of ideas or options.

Thanks in advance!

Nadmax.

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2

try increasing the nozzle and bed temperatures by 5 or 10 degrees.

3

The temps are maxed out - 70C for the bed and 245C for the nozzle when printing, both of which I believe are the default profile settings for Bambu PETG.

4

Do you have another nozzle you could try?

5

Unfortunately no :frowning: thanks though :slight_smile:

6

well that is the problem. try to put the temps on 60 for the bed and 230 nozzle

7

So, I tried printing a benchy and it came out near perfect with the default temps (70C bed / 245C nozzle). See photos below.

I’m trying to break this down logically, could the issue be related to printing speed? The benchy is a compact model, so the print head doesn’t have to go across long distances. Maybe bigger print jobs are causing filament to be flung across the plate due to rapid deceleration across longer print distances?

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8

Just tried printing the original model highlighted in the beginning of this thread, same issue, had to cancel the print - I’m stumped :neutral_face: If anyone has suggestions, am open to ideas.

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9

That is certainly a possibility. Have you tried printing it on 50% speed?

11

Thanks! I’ll give it a shot this weekend and share my findings.

12

The difference that I can see between P1S and H2S. On both printers the retraction settings (except the upper boundary) are the same. However, the PETG HF profile on the H2S is overriding Z Hop length and type, and the PETG HF profile on the P1S does not. Might be worth playing with.

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13

Awesome thanks for digging into this, will test also, eager to get this sorted.

14

No problem! Great! Can’t wait to hear how it goes!

15

Hi Everyone,

I uploaded sample images of the failed prints to ChatGPT for analysis, and it came back with the following tweaks under the PETG filament profile:

  • Cooling
  • Part cooling fan - minimum fan speed threshold - layer time: 15s instead of 30s
  • Part cooling fan - max fan speed threshold: 40% instead of 60%
  • Part cooling fan - max fan speed threshold - layer time: 6s instead of 12s
  • Filament
  • Volumetric speed limitation - max volumetric speed: 10mm/s instead of 18mms

After making the above changes I am now getting perfect prints, sharing pictures below of a model that I had so far failed to print successfully but is now immaculate.

According to ChatGPT the default cooling settings are too aggressive rendering the filament unstable during printing.

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An ongoing print with multiple parts (which I had also failed to print previously):

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Hopefully the team at Bambu can pick this up and make the changes to their default PETG profiles.

Thanks everyone for your help and input, much appreciated and happy printing!

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