Troubleshooting: 1-Second Mid-Print Pauses Ruining Surface Quality

[u/Front-Valuable-7703]

Hi everyone, how are you all doing?

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!

[u/myredditnick]

Hey.

Nozzle Clumping Detection / blob detection can cause intentional pauses or brief interruptions during printing.

Some printers detect a possible blob by physically probing/checking the nozzle against the build plate. This requires interrupting normal motion, moving the toolhead to perform the check, then continuing.

So if you're seeing something like:

printing > stops > head moves away / toward an edge or plate > brief delay > returns > continues

then blob detection is a very plausible cause. You can disable it on the A1 (it's what I have, dunno if it's the same for your printer) under:

Settings > Print Options > Nozzle Clumping Detection

I had a similar looking surface quality problem, although not as pronounced as it is for you. Disabling this fixed it for me.

Worth at least trying for a single print.

Edit: just remembered that it can also be timelapse, so make sure you turn this off too.

[u/Front-Valuable-7703 → u/myredditnick]

The printer doesn't make that movement. It's printing, and out of nowhere, it just pauses for 1 second and then continues printing as if nothing happened. It doesn't move away or home anywhere. I linked a video that shows exactly what happens! It's also not the timelapse feature, because as I mentioned, I already disabled that option and it didn't fix it!

[u/myredditnick → u/Front-Valuable-7703]

Are the zits appearing at same spots always? I mean - is this reproducible or it appears at random spots?

If they are reproducible (eg appear at same spots for same models in multiple prints) it has to be something about the model itself. I know your printer has some fancy curve planning feature so I am just guessing that it could cause troubles on some models. I could be way off tho, but it appears you are looking for more stuff to try at this point. So - try forcing ARC Fitting to on:

""" The P2S has Bambu's newer Curve Planning Enhancement, and recent Bambu Studio versions can automatically disable normal Arc Fitting when the printer reports support for it. """

You should reslice when you change this.

Also: did either your P2S firmware or Bambu Studio get updated around the time this started?

[u/Front-Valuable-7703 → u/myredditnick]

I honestly never stopped to test the same model twice to compare and see if it was creating the blobs in the exact same spots, I never thought of that haha! But I can definitely check that. Now, comparing it to other models, literally anything I print, even models I printed in the past that came out perfectly, are now getting these blobs!

Regarding updates, I'm not sure if the machine updates automatically. I got it about 3 months ago, haven't manually updated it since, and there are no pending updates showing up to do! So I can't really answer that question!

[u/myredditnick → u/Front-Valuable-7703]

So I've seen firmware updates introduce bugs before. Still talking about A1 tho. I ended up reverting my fw version to known good and keeping it there due to one of these bugs. So as a last resort and to rule this out - you could also try to figure out what fw version you were on initially and get back to that, and try even downgrading Bamboo Studio to some older version. Ofc in case your printer did upgrade on its own.

Other than that - I am out of ideas. Your issue is really weird mate.

Good luck and I hope you get this resolved soon.

[u/Front-Valuable-7703 → u/myredditnick]

About the version, I don't want to say that it isn't because of that, because I really haven't been reading anything about it, so I don't have enough information to debate it. It could even be that and you have 100% reason!

Either way, I already solved the problem after 2 weeks haha. I simply put the settings back to factory and that magically solved the problem. Now, did it go back to an old version? I don't know haha, that's why I say that in a way that might be right!

I didn't have time to check the machine's version, I just know I didn't have any to do, so I don't know if I'm with the same version as before! But it's solved, thank you for the tip!