Lines at geometry change

[TooBloo]

I’m having issues with lines in walls and sometimes inter layer cracks which align with changes in geometry nearby. See attached 3 photos, mentioned below. Finger for scale

• Printer model used - A1 Combo
• Slicer profiles used:
  White: Standard profile 0.4mm nozzle 0.2 layer height.
  Brown and blue: 0.2mm nozzle 0.1 layer height high quality and outer /inner walls order.
• Filaments used.
  Blue and Brown: Bambu Lab matte PLA
  White: Copymaster3D PLA
• Photos that clearly show the problem see attached.
• I checked and adjusted belt tension on all 3 axes to rule that out.
  I tried calibrating both flow dynamics and flow rate for each filament.
  I tried the slower high quality profile which reduces the accelerations and speeds
  I tried outer/inner wall settings.
  But still not solved
  In the brown and blue I also had cracks as well as lines.

Any ideas on how to remove these lines.
Thanks.

[JayZay]

Hi,

• My first guess is to check the slicer preview for layer time, flow, and speed. I would expect those lines to show in a different colour.
• I know you calibrated the fillament, but it seems that you could beneffit from redoing it. What’s the infill % and number of walls used?
• Regarding the cracks - did you dry the filament?

Suggestion: do some tests on smaller print files. For example, cut your model into a smaller but more representative part and use it for tests. You will spare filament and time.

[TooBloo]

Thanks for the quick feedback.
Answers to your questions:

• snapshots of slicer preview for layer time, flow, and speed attached. Speed and flow are constant, but I see the layer time is different and does seem to correlate to the lines and there seems to be some difference. This mau help to identify what is going on here
• I assume it is more important to keep speed & flow constant and layer time will just correlate to the cross section and geometry of the model. I cant see how you would be able to get constant layer time without wasting a lot in a purge tower or similar, if its even necessary or possible?
• I can try calibrating again to see how that changes things. But I see same pattern on all 3 filaments so I think its unliley to be related to this.
• For the smaller blue & brown prints the settings are as follows:
• 0.10mm layer height High Quality @BBL A1 0.2 nozzle, 4 wall loops,15% IF
• For larger white one 0.4mm nozzle 0.2mm layer and 2 wall loops 15% IF
• filament has been dried yes 12 hrs at 50C
  Yes I will try some smaller prints, however the small models were only 24 grams, so no big waste, but could definitley do it quicker and waste less
  
  
  

[MalcTheOracle]

That finger printed with excellent clarity and detail.

[TooBloo]

If anyone else can help identify some potential root causes, it would be very much appreciated. Thanks

[mltriebe]

You can also try printing the outer walls first.