Blog/2025-12-12/Spaghettification
I ruined my hotend nozzle this week and had to replace it.
How To Destroy Your Bambu P1S Hotend
Bambu Studio reloads all your filament settings when you load a 3mf file. What I didn't notice was that it also changes what each slot on your AMS2 is mapped to. So, if your AMS2 had PETG in the A3 slot, you can end up with the AMS2's settings getting overridden by the filament setting in the project file. Now, a smarter more-experienced person would look at all the mappings, re-verify that they are the same, and then send the sliced file to the printer. If there is an excuse it was because I had a few minutes between caring for Astra to do this, but the truth is that I just didn't know this was a thing. I'd printed on one filament, opened a new project file and printed on the 'same' one.
The Blowout
The problem, of course, was that I had PETG in the slot that this project had switched the filament to, and consequently it wasn't heated enough. This filled the nozzle with plastic, and then the rest of the filament just poured out of the top of the extruder. All right, this kind of problem is apparently mostly fixable. So I went over there and heated the nozzle, asked it to unload, then pulled the extra filament out and thought I was good to go.
Broken Nozzle
But then when I looked closer at the whole thing, the nozzle itself was off the rest of the hotend assembly, and PETG had blown out the back. All right, c'est la vie. So I heated the hotend, scraped off the plastic, and scooped out some from the nozzle and figured I could just print something to purge the nozzle. Sadly, this was not to be. I couldn't quite get the nozzle back on and any further attempt to print would just pop it right off. I tried a few times, and pointlessly even tried some PLA. It's obvious if the PETG won't get out that the PLA won't either so this was an exercise in futility.
The Old Ways Of Fixing
I went to our friendly neighbourhood LLM and asked it what the situation was and it told me that everything was done and there was no way out. I'd have to buy a whole new hotend assembly. "You can't salvage the thermistor", said the GPT, and I listened and ordered the assembly. But the accessory box that the Bambu P1S came with also has a replacement nozzle that is surely included because a bunch of newbies will do exactly this. I found a YouTube video to replace the nozzle keeping the fan and thermistor and the whole operation was honestly kind of trivial and took me some 20 minutes, but only because I watched the whole thing to see if I'd need anything special and then rewound and followed instructions, skipping forward to confirm.
In one sense, I got annoyed at the LLMs for all telling me this was unfixable (how easily we get used to their infallibility) but in the other I am gratified that the old ways of watching a YouTube video still work. The general truth is that with most of this software, GPT-5.1, Gemini 2.5 Pro, and Claude 4.5 Opus all seem to have an ancient view of everything. They think there are settings which aren't relevant and don't generally seem to be aware of fixing these things.
Once I got everything sorted and managed to print a couple of test prints, I took a closer look at the old nozzle and boy was it messed up. Plastic filled the inside and was crusted on the outside where it's supposed to pop out. Overall, I'm sure it would have been recoverable at the limit by heating it and doing something, but I don't think I could have gotten it to adhere properly to the rest of the assembly.
Everything has been fine so far after that.
