Beware if you remove a hi-temp filament nozzle without purging

Bambu Lab H2 Series
1

It might be obvious but I’ve just noticed that if you remove a nozzle that was previously used with hi-temp temperature that on subsequent use it might not purge properly because of low loading temperature. You may then faced clogging or less than optimal flow on your next print.

I had loaded PA6 and PAHT on 2 different prints from my 2 AMS HT connected to each of the nozzles and unloaded both filaments. I replaced the right nozzle with my dedicated TPU one (that’s my generic protocol to avoid risk of clogging) and printed. I then replaced it back with my original (non TPU) nozzle.

On my next prints, I used PETG on the left and ABS on the right. Upon loading, the left nozzle heated up to a 290°C target (The H2D remembered than the previous use was PAHT) but when loading ABS on the right nozzle, it heated it up to 240°C only. H2D remembered that the last use was TPU when in fact I switched the nozzle and the nozzle was in fact full of PA6 I used before…

This applied to my TPU nozzle but any time you replace a nozzle with high temp filament in it, I advise you to purge it by loading a low temp filament prior to removal. If not, on next use, remember to increase the nozzle temperature if necessary when loading the new filament.

2

Yes I noticed it as well. I usually use purge/cleaning filament after PPS/PPA but found its not necessary as it remembers the last filament used and purges at the appropriate temp. It did lead to some PLA dripping, but did not cause a clog.

3

I have another printer that originally came with dual nozzles, but I’ve converted it to a single-nozzle setup since it’s now dedicated exclusively to printing TPU. I’ve gotten into the habit of using cleaning filament because of its wide temperature range it’s helpful when I frequently switch between different filament types and nozzle sizes. I don’t do many prints that involve color changes, so in my two AMS Pro units, Slot 4 is loaded with cleaning filament rolls labeled as HIPS with custom settings. I don’t actually print with HIPS, so this setup works well for my H2D configuration and helps reduce the risk of clogs or issues.

Simply an alternative method that can be applied.