Bridging used to be good, now terrible

[NickD]

I’ve had my P1S a few months now, it lists 410 hours of printing; mostly with the stock 0.4mm Steel Nozzle. It’s bridging quality used to be great! to the point where all of the things in this post printed perfectly before.

Now it can’t even print a gridfinity base without severe drooping (although the texture here is also unexplained):

Here are some test towers:

• First on generic PLA, Orca temp tower
• Second Orca temp tower on Bambu PLA Matte Ice Blue 11601 (and associated profile)
• Third on Bambu PLA, but with the Orca tower imported into BambuStudio (so fixed 220° temp)

All of these have terrible short-overhang behaviour, and frequently bad long-bridge behaviour. I see the same issue with short bridges in other models.

Things I have tried:

• Under suspicion that the thermistor might be not coupled (and so too much heat), I’ve printed temperature towers (in OrcaSlicer), but the problem is consistent regardless of temperature.
• The part cooling fan seems to be working fine, strong blow of air when I set to 100%
• I’ve downgraded OrcaSlicer, and tried BambuStudio directly, no difference
• Tried printing with lid/door open/close in case it was environmental

What else could be causing this?

[RandomKhaos]

@NickD

mostly with the stock 0.4mm Steel Nozzle

Do you also use different nozzle sizes? Double check your nozzle installed is the size you expect and that you have the correct nozzle selected in the slicer.

I saw similar results when I had my 0.2 nozzle installed when I was running a 0.4 profile. It would mostly print fine, but overhangs would behave odd like what you are seeing. I spent an embarrassing long time to figure that one out.

[NickD]

@RandomKhaos

I saw similar results when I had my 0.2 nozzle installed when I was running a 0.4 profile. It would mostly print fine, but overhangs would behave odd like what you are seeing. I spent an embarrassing long time to figure that one out.

Oh my god - this was it. I’m really embarrased. Thanks so much.

I’m also honestly surprised that after a couple of weeks of printing this was the only ill effect.

[RandomKhaos]

Oh I was surprised how well the 0.2 will print on the 0.4 profile too. No apparent loss of quality, except for any area that had overhangs. Glad that it was something easy to fix!