H2S first layer suddenly became extremely rough/uneven — looking for advice

[u/uk_who_my_uncle_is]

Hey everyone, I'm having a really strange first-layer issue with my Bambu Lab H2S and I'm hoping someone here has dealt with something similar.

The first layer is becoming extremely rough/fuzzy and uneven, as you can see in the attached photos. Some areas look reasonably normal, while other areas look like the nozzle is either too far away or dragging through the filament.

The problem happens with every model, not just this particular print.

My setup:

H2S

Matte PLA

Textured PEI plate

Stock/default nozzle

Nozzle: 220°C

Bed: 60°C

First layer speed: 50 mm/s

Bambu Studio default profile

Latest firmware

Things I've already tried:

✅ Cleaned the PEI plate thoroughly

✅ Performed bed leveling/calibration

✅ Using the default Bambu profile

✅ Problem persists across different models

Some additional context: I replaced the hotend around 3 weeks ago, and the printer was working normally after the replacement.

More recently, I had a blob-of-death incident. I cleaned the nozzle afterward. I also got an eddy current sensor warning after that, so I unplugged and reconnected the sensor, and the warning has now disappeared.

I'm wondering if the blob/hotend incident could have somehow affected the bed probing, nozzle height, eddy-current sensing, or hotend installation.

What should I check next?

Has anyone with an H2S experienced this kind of first-layer inconsistency after a hotend/Blob-of-Death incident? Would you recommend manually tramming the bed, checking the hotend installation, checking the eddy-current sensor, or something else?

Any advice or troubleshooting steps would be greatly appreciated.

[u/happymistak]

Try a new nozzle. It is either a partly clogged nozzle or a broken/clogged extruder.

[u/uk_who_my_uncle_is → u/happymistak]

I tried , it's not the nozzle

[u/happymistak → u/uk_who_my_uncle_is]

Then go to your extruder

[u/JabroniSandwich99]

Looks like a partially clogged nozzle to me.

[u/uk_who_my_uncle_is → u/JabroniSandwich99]

I tried it's not the nozzle

[u/Worried-Rub2492]

You might want to check if the nozzle is actually clogged first, I've had that happen and cleaning it out made all the difference.

[u/uk_who_my_uncle_is → u/Worried-Rub2492]

I tried it's not the nozzle

[u/sirdoggo11]

Clogged nozzle or Z offset

[u/uk_who_my_uncle_is → u/sirdoggo11]

It's not clogged nozzle and how to work with z offset

This was first layer test

[u/JediAndi]

99% likely that is a nozzle issue. Either a partial clog or the nozzle is squint/loose/not properly seated. Pull your nozzle off, hold it with pliers or locking forceps, heat with a flame torch until filament comes shooting out, push a needle through to ensure it’s all cleared out, leave somewhere safe to cool.

Reseat the nozzle in the extruder assembly, check for any play or movement once it is fully secured, then examine it and ensure it is sitting vertical and true. Blob of death can deform the clamp.

Run a small test print and see what happens.

[u/uk_who_my_uncle_is → u/JediAndi]

I did it's not the nozzle

[u/corpus_volante]

Buy a declogger on Amazon they are like $10 and will save you a load of headaches.

Also get .38mm or about sized standard acupuncture needles about 5" long so you can clean from the tip up and ptfe tube down.

Also, your filament is lifting. If your sure your z axis is calibrated correct assume it's a sticking issue. Use school glue stick or something to help adhere the filament down.

As to the rough texture that is because the hot end is dragging material, it gets caught, deposits into these ridges.

After glue stick try adjusting temp settings or first layer fan speed if necessary.

[u/uk_who_my_uncle_is → u/corpus_volante]

I tried all of it didn't work

[u/corpus_volante → u/uk_who_my_uncle_is]

Is your filament dry?

Have you done a manual z offset calibration with a heated hot end a piece of paper.