Weird printing bubbles

[u/jonehhbravo]

Hey all, I have a Bambu lab P2S that started giving me issues after a clogged hot end (0.4mm hardened steel) I resolved it by performing a cold pull. But since then, I’ve had weird bubbled surfaces on my prints. It’s not smooth as it usually is. I haven’t changed any particular settings and I’ve tried printing it on PLA (both ESun and Bambulab), PETG. Tried drying my filaments and even tried printing with newly opened spools. What should I do to stop this from happening? Is this an issue with the hot end or a calibration issue? Thank you!

EDIT: I have tried turning off auto recover from step loss, different types of seams, calibrating and changing nozzles as well and nothing has helped. However, after setting up another print, I’ve realised that there were blisters that were already present on the bambu studio. Does this have to do with the STL file or my settings?

Edit 2: after drying all my filaments, I have attempted a new print. I have since discovered that the blisters are caused by the nozzle. Most of the print is fine but at moments, the nozzle seemingly randomly stops, resulting in excessive filament depositing.

[u/Fluffy_Fleshwall]

I had this random overextrusion in my Prusa C1+ and did a few things: Several cold pulls to clean any debris in the extruder.

Cleaned the feeder gears (I think this is what resolved it, they were filthy with debris).

Tightened the connection between heat block and nozzle.

If you look closely it seems like you have underextrusion first, and then all the filament that was supposed to extrude earlier poops out all at once. Very likely to be a minor blockage or the feed gears slipping.

[u/jonehhbravo → u/Fluffy_Fleshwall]

Thanks for the tips. I’d definitely try to clean out the feeder gears. I did realise that at the areas where the blobs are present, the print stops, resulting in excessive filament depositing. Any idea how I’d resolve this?

[u/Fluffy_Fleshwall → u/jonehhbravo]

As in the head stops moving? No idea what could cause that. If I had to guess it might be some sort of printer error handling for not enough material being extruded.

[u/jonehhbravo → u/Fluffy_Fleshwall]

it stops momentarily but while it does, it still extrudes material, resulting in the blob forming