Hello! I am pretty new to 3D printing, so I am not quite sure in which direction to go with this issue.
let me start by saying that I am using a brand new filament for this print. It is regular PLA filament and is not a support filament. I had used the same exact 3D model and slicer settings previously for the same print and it came out very nicely (Also a PLA print). The only difference is time. The first time I printed this model was in March. My new print (Shown in photos) was done yesterday. I have a hunch it could be something with the printer. I wanted to switch the nozzle out first and try that, but I wanted to get an idea for what else it could be before I do that.
New filament is frequently wet. Those bags slow water ingress, but they do not stop it. So it is best to dry the filament if print errors occur to eliminate that possibility first.
I’m not sold on that being a moisture issue. Could be, but I don’t see the signs of moisture bubbles bursting (bad quality everywhere or all over). My guess would be a tweaked profile, or a bad tweak that is reducing the quality. Tweaks to the fan/cooling profile would be the first place to look. But personally, I would just use the base standard PLA profile.
If you haven’t played with the settings, check to see if your fans are coming on, Part cooling fan and the AUX fan. When using PLA the AUX fan really helps with high speed printing and the Part cooling fan (right under the head) are always critical to overhangs and bridges.
If the fans are coming on and you haven’t played with the settings, try smaller layer heights. The smaller layer heights will always yield better overhangs.
If you still find nothing wrong after all that, make sure you are not using the Sport and Ludicrous speeds for these relatively steep overhangs.
In all honesty, the printer should print that all day, straight out of the box. So IMO, something has been changed or is broken (possibly a bad roll of filament).
This is extreme case usually with PETG mostly.
Most of the time the extra 5-10% moisture content will just increase thermal mass and thus require extra cooling. If not, overhang area won’t be solidified quick enough to keep the shape.
But it could be the additive (like dye) changed the thermal mass slightly which resulted in bad filament if you didn’t add extra cooling or reduce nozzle temp.
Beings its PLA, and the cooling is through the roof, I don’t think its as nuanced as you are making it out (but I could be wrong). My guess is its still a cooling issue where its either a changed setting, broken fan, or an outside chance of bad filament.
Moist filament always shows as inconsistent extrusion (bursting bubbles). But don’t assume the the bubbles have to be significant. Many times they are too small to recognize as bubbles but I’m referring to the very small ugly extrusion breaks associated with wet filament like the image below. Note: The photo shows an absolute perfect example that isn’t really what people see in their prints, but I think it shows the bubbles well.
Also, I don’t want to completely dismiss moisture because the photos the OP posted are heavily smoothed with noise reduction, so its difficult to see the real state of the extrusion to determine moisture level (as I do see some oddities in there). So don’t take my post as gospel, its my best guess. Nothing less… nothing more.
Please note that bubbles are neither the only nor the first symptom of moisture ridden filament.
In fact, it is pretty much the last.
Long, long, long before bubbling is observable, or audible for that matter, two important and drastic effects occur:
Moisture lowers the filaments viscosity, leading to increased stringing and oozing.
The high thermal capacitance of water leads to a slower cool down, increasing geometry induced thermal mismatch in a given layer while also keeping prior layers softer for longer. This in turn leads to drastically increased curling.
=> Curling can be used as an early warning for moist filament.
=> Please ensure to first rule out the basics before addressing settings. There’s no point in optimizing settings for sub-optimal (i.e. moist) filaments.
I’m going to ignore moisture here and say that this model should be printed 100% perfectly with half-decent supports. It looks like your support interface is bonded to the bottom layer, and when you cracked supports off, the interface (and more) stuck to the bottom.
Since you’re on 0.12 layer height:
Try increasing your top interface layers to 5, and drop Top Interface spacing to 0. Check in the preview what this does to that interface layer [ dark green ]. This will fuse and snap off together away from the model much easier, and likely not leave behind so much crud.
Would also recommend tree, but that’s a preferential thing. This model should be fine for standard if you wanna keep on keepin’ on.
This is another reason why I’m mostly discarding the thought of moisture… there is no real stringing to be seen, along with the other aspects that should be there.
I’m not sure how much I believe this, but if true, we are talking about less than 1% by volume (somewhere around 0.5% for PLA). Again, the effect would need to be very slight if accurate. Honestly, with moisture being present, I would expect the bad extrusion to increase surface area and increase the effect of cooling (due to the gaps introduced). And when I search, I find that water has more than an order of magnitude better heat transfer coefficient, so again… not sure I buy into the thought that moist filament has issues cooling, but I haven’t done any research on it. Do you have any documentation or articles that backs up that claim?
I am afraid that moisture is such a basic and fundamental topic that I do have to politely decline your request for unpaid private tuiton and embark on your own (literature) research.
The forum and the Bambu Academy courses are good starting points. You will find plenty of threads on moisture and drying which are freely at your disposal and give you the right locations to raise detailed questons and discussion points.
This thread started as a specific troubleshooting request and would best be served if not derailed too much. In particular since there indeed is a ton of information freely available.
