Print has voids and gouges

Just converted my P1P to P1S. My P1P printed flawlessly. I print mostly PETG and a bit of PLA. The attached images show a part printed with the door open and top off using Bambu Basic PETG. I used the Bambu Basic PETG settings.

Do you have any idea of what is causing these voids and gouges?

Thanks… Richard

Looks like Pressure Advance tuning is wrong. Run filament calibration?

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I’m not familiar with the filament calibration, but it seems strange that these errors started just after I converted from P1P to P1S, and I am still using the Bambu Basic PETG.

The only thing I can think of is that the heat sink on the MC board as pictured on the Bambu conversion video, showed the fins of the heat sink running horizontal so the fan can pull air across the fins. The fins on the heat sink supplied with my printer run vertically. This makes it impossible for the MC Fan to pull air across it. In fact, the heat sink is blocking the flow of air. Bambu notes that insufficient cooling will result in lost steps. Do the defects in this part look like they are the result of lost steps?

Thanks… Richard

No, it doesn’t look like lost steps to me. You’d see distinct shifts from one layer to the next. This looks like the extruder isn’t pushing enough filament at the start of those defective areas. Though it’s also possible the filament needs to be dried. I can’t tell you how many printing issues I’ve chased that turned out to be the filament being soggy.


Thank for your thoughts. I have never dried a roll of filament before. Is there an easy way to do this?

The filament I am running is a new roll. Also, would you agree that this does not look like a plugged nozzle? I think for a test I may try printing another roll I have of Hatchbox PETG.

Thanks… Richard

Yeah. New roll not needing to be dried is a common misconception that I too once subscribed to. I’ve learned otherwise. If you don’t own a filament dryer (I’d recommend a Sunlu 2 if you want to buy one), you can use the printer. Put the filament roll on the heated bed and turn the bed on, setting it to 60ºC for something like PETG, and leave the roll there with the door shut for a day (flipping it over halfway through). Then try printing with it.

Doesn’t look like a plugged nozzle to me. It’s either got too much or too little filament every place the printhead had to make a 90º turn. That’s Pressure Advance or flow. Both of which can get messed up by moisture in the filament.

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Thanks so much for your thoughts. Right now I am testing a smaller print with Hatchbox PETG. If that doesn’t work… Tomorrow I will certainly try drying out the Bambu PETG.

Funny… I live here in AZ in the dessert. We rarely see the humidity go over 22%. Now it is Monsoon Season and my shop was at 53% today and 40% right now. I think you may be on to something here. Again… Thanks for your thoughts… I will keep you posted.

“It printed fine a few days ago, now it won’t print at all” = humidity went up. :slight_smile:

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I live in AZ too and the only time I’ve had wet filament issues is with brand new out of the sealed bag filament. I now dry EVERY roll I get before use just to be sure I’m not chasing ghosts.

You’ll definitely want to familiarize yourself with filament calibration as it will be key to successful 3D printing. Your issue may be as simple as doing a power cycle, recalibrate the printer and then run automated or manual flow and pressure advance calibrations.

Thanks. I ran a smaller print last night using another roll of PETG and it worked great. I am drying the original roll as suggested by Randy and will try printing it later today. Definitely seeming like a moisture problem!

I am very interested in better understanding the filament calibration. I did recalibrate the printer from the LCD display after converting P1P to P1S and it reported “successful”.

I read the Wiki with respect to filament calibration and am a bit confused. The filament flow calibration says that it can be done manually or automatically. I do not see an option to start the automatic calibration. I watched the Youtube video from Bambu and it does show the automatic button (see below screen shot ) If I select manual calibration, I see the drop downs and the button to start.

There is also a note regarding the textured print plate (see below).

Are you suggesting that I perform a manual flow calibration? Does this mean I need to cover the entire textured plate with the glue?

Thanks… Richard

I’ve had my printer for almost a year now and the auto calibrations were not very good so I used an alternative slicer called Orca Slicer to manually calibrate all my filaments. I’ve experimented with the newest software and firmware versions and the auto calibration for the Pressure Advance (PA or K factor) has been really accurate. If you’re getting good results that way then stick with it.

I mostly use 0.6mm nozzles so the auto flow rate doesn’t work for some reason so I do that manually.

You can run the auto PA calibration on a smooth sheet and then switch the plate out for the textured PEI for your prints. The Engineering plate with glue stick worked well for me with PETG and ASA. I don’t use glue on the textured plate with PETG but I need it for ASA.

Thanks. I have only been using the textured PEI plate with the PETG and it has been working great. Thans for all your help.

  • Run the machine calibration , after hardware mods or firmware upgrade recalibrate always
  • Dry the filament (must no matter if new )
  • Test the flow calibration and dynamic calibration(pressure advance) - recommend to use orca slicer easy to understand and do any calibrations: Calibration · SoftFever/OrcaSlicer Wiki · GitHub , i use only orca slicer with X1C ( note it is a bit print temperature dependent for perfect result)
  • Reduce the print speed to less than 140mm/S
  • I Use the printer and cover closed but add some chamber exhaust fan around 70%-80%
  • If you use textured plate autoflow calibration( pressure advance) does nor work, and in general does not work very well
  • normal flow setting is not done by bambu it needs to be manual tested and added in the filament , latest Studio release has automated both calibrations , still recommend orca slicer simpler and better and Studio do not get best results with auto one and the manual not great

The problems looks like under extrusion on speed change which points do pressure advance not calibrated, but similar symptoms with wet filament

Vladimir… Thanks for your thoughts. Very interesting. I dried the roll for 8 hours and tried again. The defects were in almost the exact same places. I bought a filament dryer just to be sure.

I think I understand your suggestions but am a bit confused as how to execute them.

  1. You want me to use Orca Slicer to test the flow calibration and dynamic calibration. How do I transfer the test results from Orca to Bambu Slicer? I want to be able to print from Bambu Slicer through Wifi. Do I run the manual calibration with Bambu Slicer and enter the K values that I got from Orca? Is there an easier way?

  2. You suggest reducing the print speed to 140mm/S. Is that the Travel speed, or other layer speed settings?

  3. Lastly, there appears to be filament accumulating on the nozzle while printing. Is this related to the same problem?

Again… Thanks so much for your detailed response.

Best… Richard

Hi Richard

  • Q1 the flow it self should be transferred automatically if the Bambu Studio is closed, while using Orca slicer and when the filament gets stored on the cloud some delay maybe. Noticed if i have it open don’t get transferred and some times takes some time so i did it manually a few times in the past.

The K value in the older Bambu slicer need a K command in the filament , example: M900 K0.18
For the new one not sure as there is already K factor and probably needs manual edit, not sure when is it applied and may overwrite your K command i did very short play with the latest Bambu studio, when my current print finishes may try it and give more detailed advise. Or some one else here. It is 24H print and 16H to go
M900 [K] [L] [S<slot>] [T] , Linear Advance Factor | Marlin Firmware

  • Q2 Print speed 140mm/S is print speed not travel i do reduce the outer walls only (70-50) to get a shiny PETG . You can get very nice finish . See my default speed settings for PETG, ABS, ASA

  • Q3 Yes If filament is accumulating on the nozzle - most common is either flow rate incorrect, K factor incorrect . Some times you may experience the same if the speed is too fast as well or the print temperature and cooling is way off

Note on filament : from what i saw on your posts only one filament of PETG is making problems, the other is ok ?
If the same brand and color and do not have problems with the other roll filament then could be just this row( bad batch) the 1.75 size may vary and so the calibration values. Some cheap brands are really bad from batch to batch. if it is from a different brand, then I had really bad experience with one roll of PLA and one PETG and as they were old went in the bin. With the new filament when i had a trouble with good layer adhesion with 10 rolls of ABS and i was offered to be returned and replaced , but at the end i found that with a specific settings issue was resolved so kept it. But the company was happy to replace . The solutions was only 5C print tempo increase and 10C in the plate and long soak time before print ( Warm up the chamber for 30Minutes-40 )
Different brands has different Print temp, flow and K for the same material , different colors usually pretty close but also may very . I do not calibrate colors unless i see some issues

Note on Q2 , i stopped using Bambu Studio in general , only Orca slicer, so have not really checked how to transfer the K factor any more on the latest Bambu studio. Only from time to time update Bambu Studio it and check what is new. Orca slicer has everything that i need and more, and they are more or less identical in features and experience usually orca slicer has a bit more usually


Orca slicer setting the same as the Bambu with Enable pressure advance difference

Note that colling AUX is set at the moment to 0 but i do increase it for PETG on some prints to 20-40% , Some time instead of AUX add Chamber fan 40%, which can be done manually or with custom G command . It is winter here and the AUX and Chamber are off as the ambient quite low
Note that the Part colling fan max speed is set to 60% i do increase it on some prints to 70%

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Thanks for the nice explanation! 1st off, I made a small mistake previously as the part I printed with another brand of PETG that printed fine, was a simpler part and not a good test.

Prior to posting on this forum, I opened a ticket with Bambu labs. Their suggestion was "Our PETG profile for enclosure P1P or P1S is not tuned to perfect, especially in the overhang area. Can you try to go to the filament settings and change the volumetric flow from default 13 to 10?

I made this change, reprinted the part again and it looked better but still had smaller imperfections in the same places. I then ran the flow extrusion calibration and printed the part again. This time is looks much better… but still not perfect (see below). Not sure what I can tweak next get a better print.

Thanks again for all your help!!

Well done , i would suggest you to reprint the temperature tower pick the best temperature and redo the calibration with the new temp, It can be a bit of a mission fine tunning especially PETG, from what you show , it looks like the flow and K is still not perfect and also the Print Temperature does not look perfect ,
Note that Fans still may affect it especially for overhangs. Try to change Cooling overhang threshold and play with fan speeds between 100% to 70% . Probably i would pick smaller object for tests initially

Probably worth to reduce the outer wall and top surfaces print speeds as well as overhang speeds

I am using X1C , so not sure how the calibration works on P1S , but i do manual calibration only as the autocalibration does not give me consistent results which should be the same for any printer, and using only orca slicer as have a lot more easier tunning calibration tests and well explained
Also it works for my Prusa , and use the same technique to calibrate on it as well

Also for best look i prefer ASA or ABS material as with PETG difficult to get perfect result sometimes

Good luck

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Just circling back. I took you suggestion, made a test part with the same geometry, reduced the outer wall and top surface speed to 100 and the part printed awesome!

Thanks so much for all your suggestions. I will certainly print a temperature tower and fine tune further when I get a chance. I cannot say thank you enough.

Best… Richard