I am new to the H3C, although I am a long time 3D printer.
I have noticed curious behavior with my H3C and purging. I have a multicolor print, mostly PLA but a PETG filament for suppoprt interface layer. Out of a 500 layer print, perhaps 20-30 are interface layers.
I have noticed that most times when the toolhead goes to pick up the PETG PrintTool is goes to the back of the printer and purges a little bit. This is much less than my P1S and P2S, but it still takes a significant amount of time, probably 60 seconds. Most of the time when changing printtools it is fast, like the advertised 6 seconds.
Why does it do this? I understand that when initially loading filament into a PrintTool there is a need to purge some, but why in mid print?
yes I have noticed it sometimes purges in mid print
I don’t know why, but the thing i can think of is that maybe some motion took longer than expected, and therefore pre-heating the next nozzle started too early or too late. The print time in the slicer is after all an approximation.
if this is the case, I suspect this might get fixed in an update.
Mhm, interesting. I had a look at an H3C slice using PETG as a support interface in Studio. But I did not follow the latest update and am still on 2.9.1.70. In that slice, I do not see the travel move to the back of the printer. Only to the backside of the prime tower before doing a “side scrape”.
Since there’s a bit over 150 lines in the gcode for the complete swap (implemented through the Filament start g-code machine setting) and the Bambu gcode is not well documented, I asked Gemini. Unfortunately, it is speculating as much as I do
Out of the main points it mentioned, we can probably already rule out “High Flushing Volumes & Matrix Multipliers” as you mention the purge volume to be tiny.
What would make sense to me would be “Conservative Extrusion Feed Rates”. With my H2C, the purge line goes down painfully slowly for example with a 0.2mm nozzle due to the much lower max flow and much more rapid pressure build up. That could explain a much longer purge duration than normal.
Is it actually purging for the full 60s? (Pointing to really slow feed rates) Or is it purging and then waiting for ages?
As @Eponymous mentioned, I expect Bambu will tune this further.
I don’t know if it is purging the whole time, I find it hard to see the filament given the small space in the back and my almost 70yo eyesight. I would think, given the small size of the poop, that it is purging and then waiting.
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