I have a model with a curved shallow slope which exhibits pretty significant lumps / waves / bubbles (not sure how to describe this?). I first noticed the problem printing in Bambu Lab PETG HF; after over 20 test prints tweaking one setting at a time, I tried Bambu Lab Basic PLA and got a nearly identical result. I moved both filaments over to my A1 and they printed the part no problem.
In the attached pictures you can see the bubbles are raised where there is a gap between where the infill touches the walls.
I have tried the following with several different spools of PETG HF all which were dried for 8hrs before use:
Manual flow rate calibration
Gyroid, Cubic, Rectilinear infill
Flow rates between 0.93-0.99 (0.01 increments)
Nozzle temp between 230°C-250°C (5° increments)
Aux fan 90%, part fan 0%
Aux fan 0%, part fan 100%
Door closed
Door open
Lid on
Lid off
2 wall loops
3 wall loops
4 wall loops
“Silent” speed - only 1 of these prints and the bubbles were very slightly reduced but still quite conspicuous.
I store my filaments in sealed containers with desiccant and the room I print in is 69°F with ~35% humidity. This P1S has about 80hrs on it while my A1 has over 1400hrs (the A1 prints the part without any issues). I am at a loss as to what the problem could be. Any ideas?
I usually associate these type of bumps with solid infill edge curling. I find that particularly difficult to tackle though.
For PETG and PETG HF, I usually copy over the cooling values from the Generic PETG profile while slowing way down (<100mm/s for PETG, <120mm/s for PETG HF, all accels to 25% of defaults). It may be overkill on the HF stuff, but overkill is underrated
In addition, I usually use adaptive layer height to ensure a minimal layer height at shallow angles as that also helps against curling.
And of course, with curling being caused by a hot layer partially supported on a cooled layer cooling itself, I try to keep the build chamber as warm as possible while pulling off the trick of avoiding heat creep.
All of that helps with really thoroughly dried filament but I unfortunately can’t claim that this combination will always lead to success. I have however little experience with further remedies (turn off enforce top layer number (can leave holes) or playing with the number of top layers.
I think it is definitely a problem with solid infill; the problem areas in the pictures from the original post align with the solid infill line type (purple lines in the picture below) shown in Bambu Studio
I tried the cooling suggestion you made with no luck. Next up is slowing the print speed down (as suggested), however if that ends up being the solution I will be pretty disappointed since I am able to print with these exact same spools of filament the exact same model on my A1 and the result is flawless.
Unfortunately, I do not have an A-Series. Its nozzle pressure sensor could have some good effects on print stability and extrusion temp.
But it gave me another question. Occasionally we see some strange filament defaults. Do you have a PETG HF setting difference between the A1 and the P1? It shouldn’t be, but stranger things have been observed.
Many thanks. That is very helpful. Maybe I will learn better settings
If the A1 settings work on it, I’d suggest just using those with the X1. Flow, Nozzle temp and cooling all play a factor in curling and warping.
I am not sure if the change in cooling isn’t on the low side compared to generic PETG but if it works…
I’m having a similar issue on a print of mine.
I’m using a P1P and I originally thought the top-surface artifacts were a result of bad support (the geometry of my print means that the problematic part is only supported by support material until it connects with the rest of the print at the end). After really tuning in supports - I realized it may be a result of some sort of curling. I’d be very interested to know if you’re able to solve this problem.
I’ve tried a variety of solutions so far:
Thoroughly dehydrating my filament
Reduced speed for overhangs, infill, top/outer walls
Layer height down to 0.12mm
Sparse infill from 0% to 50%
Various top/bottom surface layer count adjustments
I’m interested to try making the enclosure warmer and using a higher fan speed. Also glad to have found this post because “curling” might be the key word I need to find other people who have had this problem.
Some pictures I forgot to add. I have a video too in case anyone knows how I can upload that.
The video shows the extruder colliding with the edges of the print as it lays down a new layer - especially on the outer wall. As a result, the print flexes during the collision. I had originally thought I could fix this with better or more support material but that doesn’t seem to solve the problem. It gets worse as the print goes on.
For some reason the forum won’t let me add photos or a link right now, here’s the imgur link:
That part looks like a prime candidate for splitting and gluing.
If you want to treat it as a torture test, I doubt that only printing with a warmer chamber will do it.
I’d recommend changing settings drastically for the top: a 0,08mm layer height, slowing down to 50% on speed, to 25% on accellerations, not using sparse infill but increase the wall number and, most importantly, print two (or more) at the same time or at least enforce a prime tower.
The reason for the latter is that the vid suggests you also having an issue regarding minimum layer time. Which the minimum layer time addresses in a counterproductive way (keeping the hot nozzle in an area not yet sufficiently cooled).
Hmm, if really curling of the inner walls or solid infill on the edges is the problem, then reversing print order to outer-inner might help for that specific problem.
Thanks so much for these thoughts. I just started a new print with 25% acceleration as you had previously suggested in another comment.
I’ve definitely tested reduced speed by about 30% but I’ll try reducing even further and I definitely haven’t tried a prime tower.
Can I ask a follow-up question about the prime tower? This print is actually typically part of a larger print and so typically the nozzle will go print elsewhere in between layers on the shown example. Would this effectively achieve the same thing? Just trying to decide if I need a prime tower still when doing the full print as opposed to just this quick iteration test sample. I suppose the prime tower in this sample would at least provide a better representation of what it would experience on the full print anyways.
Also… I’ve considering splitting and gluing but it kind of ruins the aesthetics of the part. I’m really hoping to get something acceptable with supports. Even if it takes a few hours longer to print because it’s slow, it’s not work I have to actively be doing which seems worth it to me to just have it come out done.
I think that ideally, you may not need supports. But as toa prime tower, a duplicate, a tall primitive cylinder or further geometry added to the part, that is difficult to say. You could try to get an estimate by experimenting with these in the slicer. You do want to achieve a layer time well above the filament min layer time. Maybe target a factor 2 for the thin section.
I could only view the vid on my mobile so noz much detail. But it did look to me like you have less of a curling and more of a layer time softening issue as the entire top part seemed to be moving. I’d give duplicating (or even triplicating) the print a go with a big distance between the objects. To test it out, you could also move the parts lower into the buildplate to only focus on the troublesome tops at first. It’ll be a bit warmer close to the bed, vut you can see if you are on the right track.
I think I may have solved this. Changing the internal solid infill speed from 250mm/s to 100mm/s all but eliminated the bubble/wave on the sloped surface. Pictured below is the full difference between the 0.20mm Standard @ BBL X1C (Left Preset Value) profile and and my current settings (Right Preset Value). Before changing the Internal solid infill speed I was getting bubbles with the other settings in the right column
Next I am going to try a test print using 0.20mm Standard @ BBL X1C as a starting point then decreasing Internal solid infill to 100 to see if I can reproduce the an acceptable result. I want to trust the system presets as that all I have ever used up to this point (save for adjusting the infill pattern).
Same spool of filament in the pictures below below; the camera can’t decide how to set the white balance.
Last night, I created a profile to achieve high-quality ironing. While the print surface is exceptionally smooth, the ironing process still results in fine fluff appearing sporadically.
I adjusted every speed setting available in my original PETG HF profile, including those related to ironing. The most significant factor I discovered during my work with PETG HF was the importance of proper filament calibration, none of my spools matched the factory presets. For instance, one spool required a K-value of 0.08, another 0.023, and a third 0, among others. Therefore, it is essential to calibrate each filament spool individually, along with ensuring proper drying and preparation.
When printing parts for my beehives, I don’t prioritize eliminating stringing and often use a default process profile. My bees take care of the woolly texture themselves.
I am now beginning to think the problem is with the printer itself. The wavy surface artifacts show up consistently on a variety of both PLA and PETG spools on this P1S printer. Using those exact same spools with the same models and factory profiles on my A1, the results are flawless.
Is it possible this is a belt adjustment issue? I’m scared to adjust the belts for fear of making the problem worse.
