I was printing large objects with clean first layer (which is required for this to be usable) maybe 4 or 5 weeks ago. Printed like 3kg of parts and they all were superb.
What is going on ? Seems that it is a firmware issue rather than particular AMS/filament/printer.
Although there is no way to prove this theory, but I am willing to wager that based on the number of similar posts we have seen on this precise issue in the last three weeks, humidity in the Northern Hemisphere might be playing a role. This has been happening to me on certain select filaments in like manner to what you have shown. Iâll share my method for a remedy and hopefully it will apply to your situation.
At any rate, donât assume that filament shipped a month ago is made with the same precise formula as the one shipped this week.
The issue youâre displaying has been happening to me with known filaments that Iâve calibrated. Hereâs what you might try that worked for me:
Perform a first layer test using a cube primitive similar to what you displayed. A 100x100x0.20mm is sufficient to show ripples. For a full test, use 240x240x0.20mm. Ensure you can reproduce the error shown in your photo.
Adjust the filament settings by dialing back the flow ratio to something extreme. The default is 0.98, so dial it back to 0.80. The goal is to force a change in results, not to get it perfect, that will come later.
Perform the same print test on the same model and compare.
As stated, this test will only show you what effect, if any, is happening via the filament profiles. With a 0.80 flow ratio, I would expect youâd see voids in the filament path, not the over-extrusion youâre showing now.
Once youâve either ruled in or ruled out filament settings, you can move on to dialing in the correct settings using your first layer test.
Believe it or not, I looked at my humidity logs from January versus now. My office humidity has only varied 10% higher in the summer months, but it has been consistently above 50% even when I run the filament out of a dryer. Filament profiles that I trusted and calibrated myself stopped producing the same results as six months ago, which is why I started to trust nothing and reverify my calibrations using this simple first layer test.
This post got me curious. So I went back and looked at recent calibrations I did where I still had filament on hand. It turns out I had a few ounces of overture that I purchased over two months ago.
Note my original calibration settings where the flow ratio was set to 0.98 which is the default. Although I did not save samples then, I can tell you that the first layer tests were on par versus my second calibration about a month ago when results started to differ. They were dialed back to 0.93.
Something weird is going on. I was playing around and seems that it is working again. Even for filaments without full calibration beside the flow one.
I start using default starting gcode (I have removed several months ago the second line and improved number of moves during nozzle cleaning). Seems like newest code has some changes in calibration during the starting phaseâŚ
It prints again fine⌠But I was testing out my old gcode and it also worked⌠So I have no idea what is going on. Perhaps humidity but normally I have 42-46% during a day (and 24-26 degrees C)
I restart machines, re-did the calibrations but nothing has worked instantly. Changed even version of Bambu Studio.
The important thing is that it appears you have resolved the issue. However, I understand your frustration with the mystery. Why exactly did it fail in the first place, Iâm sure youâre wondering.
The key here is that you introduced step one of troubleshooting 101, which is to restore the experiment back to a âknownâ state and repeat to verify your results.
Although itâs too late to verify this next theory because the scenario has changed, if I were to speculate on a possible cause for the over-extrusion you were experiencing, it might be that you had filament buildup in the hot end. While this is unlikely, it could explain the circumstances. If this happens again, one experiment you might try to rule this out is to immediately change the filament to a contrasting color upon creating an unsatisfactory first layer and repeat the process. If there is buildup, the contrasting color will show up immediately as residual filament, indicating buildup.
----- EDIT ----
This is an intriguing topic indeed. After posting this last response, I just remembered that I had the last vestiges of a spool of Overture PLA in my dryer. It was in there for 20 hours. Normally I wouldnât dry PLA but I wanted to test out this theory. Unfortunately, I neglected to weigh the spool before and after but truth be told, there is so little left on the spool, I likely wouldnât have been able to get an accurate moisture weight.
Look at the results based on yesterdayâs print. Almost a complete absence of the ripple affect suspected to be caused by moisture, albeit now it looks like under extrusionđ but it at least proves that moisture can contribute even when weâre talking about PLA. To say the least, this was not expected.
