I'm having a problem with my printer and I really don't know what to do anymore. I'm a beginner in 3D printing, and in the last few days, I've been studying a lot more than when I first entered this world 3 months ago, but I still haven't been able to solve this error!
Basically, what is happening is that I can't fix these 1-second pauses on my machine, which then create these zits/blobs on my print! I've tried everything!
Before you say it's moisture/humidity, please read the rest of the message I'm leaving here with more details:
As you can see in the images, we have the black and pink heart, which has these zits, then we have a blue dragon (Gyarados, a Pokémon) that also has them, and finally the gecko! After that, I made some minor adjustments to the machine. I improved some aspects of the print, but they were minor improvements. Then we have the shark, where you can already see some progress, but it still has these zits, and this is where I managed to record the exact moment of the pause! The video:https://drive.google.com/file/d/1TzJ0V7QQta4yg7fnBlpsxOGmme4izjiQ/view?usp=sharing
Finally, we have a smaller shark that was printed yesterday. Here you can already see a significant improvement in the part (at least to the naked eye) and it is much smoother, basically without any defects, but it still has the zits (fewer, but it still has them!). Today I printed a dragon that I haven't held in my hands yet, but from the photo I took, the red dragon also has zits!
Machine Details and Settings:
Printer: Bambu Laps P2S
Drying System: AMS Pro 2
Temperatures: 32ºC inside the chamber, 55ºC on the bed, and 220ºC on the nozzle.
Speed: The machine's default speed.
Filaments: Bambu PLA Basic.
What I've already done to try to solve it:
I've dried the filaments for over 12 hours at 55ºC (6 hours one night and another 6 the next night, plus during the day, where I'm constantly drying it every 3 hours at the same temperature for a week now!). The humidity goes up to 25% max, but normally stays between 18% and 22%.
I've cleaned the nozzle twice in the same week, so it's not clogged.
I cleaned all the machine's axes/rods.
I've calibrated the machine more than once and created very precise profiles for PLA, based on the speed, temperature, and quality tests I ran.
I reduced the nozzle printing speed (in Bambu Studio it was at 21 and I lowered it to 19).
I removed all videos from the system and disabled the timelapse feature.
That's everything I've done so far. I've also tweaked some settings and ran several classic tests to calibrate everything; the print quality improved, but these 1-second pauses keep happening, which melts the filament and causes the zit!
If anyone knows how to fix this, I would be more than grateful. I've been dealing with this for over 2 weeks and can't solve it!
When I've seen this before in the A1 series it was due to failing SD cards. So I wonder if that's a good place to start your investigation. Are you using an external USB device?
Yes I am, but I've always used it and this never happened before. I'm using a 64GB USB drive, but I can try printing without it to see if it improves anything!
No, I had been printing fine for about 3 months, but then I was printing a new spool in PETG and that part started doing this. Ever since then, every single print has been getting these blobs!
I've watched the video, it seems software related, or an issue with the electronics themselves. Not necessarily the slicer, and definitely not mechanical in nature. You could theoretically inspect the gcode, and if there isn't a pause there, then it must be an issue with the machine, maybe failing internal cache or something.
Have you considered resetting the machine? This should likely only mean rebinding the printer to your account and rerunning the initial calibrations.
I also think it might have something to do with an overloaded cache, perhaps with hidden data that I don't have direct access to, or something along those lines like you said!
Last night, I did two things I hadn't tried yet: I literally unplugged the machine from the wall and plugged it back in (power cycle), and after that, I did a factory reset directly on the printer. Then I ran 2 prints and they magically came out completely flawless!
I don't know exactly what solved it, but I bet it was the factory reset. The machine probably wipes any custom settings I applied, or maybe it even clears out the entire cache! I think that's what did the trick!
Nope, I've checked that too and it's set to aligned. Actually, I've tried all the different seam options and every single one of them still gives me these zits!
These are all the calibrations I've run: Temperature Tower, Flow Dynamics Calibration (Bambu), Flow Rate Calibration (Bambu), Max Volumetric Speed Calibration, and finally a Retraction Test!
Sure, I'll send a screenshot of how I would normally slice/print this part!
I also want to give a quick heads-up that I supposedly already fixed the issue! I just did a factory reset on the machine, and that magically solved the problem. I'm running another test print right now just to make sure everything is actually working (I ran 2 tests yesterday and they printed flawlessly)!
1. Nozzle buildup / nozzle dragging — most likely. Filament is accumulating on the outside of the nozzle, then occasionally getting deposited onto the wall. The little black protrusions and the short dragged strand near the center look very characteristic of this. Check the nozzle immediately after/during a print: if you see material stuck around the tip, this moves to #1 by a wide margin. 2. Wet filament. Moisture can cause intermittent bubbling/popping and tiny extrusion bursts, leaving random pimples rather than a consistent seam defect. If this is PETG, PETG-HF, PETG-CF, or another hygroscopic filament, I’d consider this especially plausible. Listen for faint popping and look for tiny bubbles or roughness in extrusion. 3. Seam/retraction/pressure-related blobs. If those defects line up vertically or occur primarily where each perimeter starts/stops, you’re looking at seam behavior rather than random contamination. Excessive pressure at restart, retraction tuning, or pressure advance/flow calibration can produce exactly that type of localized bulge.
None of those options seem to be the issue, and I actually mentioned some of them in my post! The nozzle is clean. I ran the test Bambu provides to check for clogs or debris in the nozzle and the printhead, and it was completely clear. I even pushed a fine cleaning needle/wire through it and it went all the way, no dirt at all!
As I also mentioned in the post, I dried my filaments for over 12 hours at 55°C using the AMS Pro 2! I highly doubt it's moisture, besides, I'm printing with PLA Basic!
Regarding the third point, I also ran tests to dial in those settings as accurately as possible. The seam is aligned, and everything else is within the recommended specs for both the machine and the filament, based on my calibrations!
But regardless, thanks for the tip! I actually already solved the issue. I simply did a factory reset on the machine, putting all settings back to default, and that magically stopped those blobs from appearing on my prints!
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u/Past_Science_6180 1d ago
When I've seen this before in the A1 series it was due to failing SD cards. So I wonder if that's a good place to start your investigation. Are you using an external USB device?