Like the title says, in the filament settings i set the Auxiliary part cooling to be at 0% (in the cooling tab) but when i print the fan mode is on heating and the Auxiliary part cooling fan is at 100%.
I’m printing with ASA on a P2S, i suppose this isn’t that much different than other topics here on this site, but anyone got any tips on this bug?
What? How can the fan mode be set to heating when the P2S doesn’t even have chamber heating capabilities?
Sounds weird. But can you change the fan mode to cooling, or just set the aux fan to 0% on the printer display after the print has started?
I can not change it to cooling after starting the print, but yes i can set the aux fan to 0% on the printer display after starting it, but its really inconvenient because i have to do it two times… (The first when i start the print and the second when it’s halfway through the print)
Shouldn’t this be addressed by bambu lab?
I know of changing the gcode, but i don’t really trust pasting in code i don’t understand.
Ill post some gcode and explain it when I get back to my computer.
Short answer why it does this is that it will still try to regulate the chamber temperature.
; M145 P0 ; DISABLED - prevents setting airduct to cooling mode
M106 P2 S0 ; turn OFF auxiliary fan to retain heat (was S255)
M106 P3 S0 ; turn OFF chamber exhaust fan to trap heat inside (was S127)
M1002 gcode_claim_action : 29 ; Bambu internal action claim (leave as is)
; M191 S0 ; DISABLED - prevents printer from waiting for the chamber to cool down
M106 P2 S0 ; ensure auxiliary/chamber cooling fans stay off (was S102)
M106 P10 S0 ; keep left aux fan off
; M142 P6 R30 S40 U0.3 V0.8 ; DISABLED - prevents the exhaust fan from automatically turning on when the chamber gets warm
Ok. I added some notes on there, let me know if there is something you don’t understand. You just need to paste this into the filament start GCODE.
Gcode is actually really easy.
M codes are machine commands while G codes are movement commands. P refers to the part codes.
P2S uses “partially active” chamber heating. It still heats the machine passively through using the heat from the bed, but also controls the heat in the chamber through the use of is fan ducts.
But for what reason did Bambu make the machine code start the auxiliary fan when printing ASA? When printing ASA, you want as little air circulation as possible and a high chamber temp. The aux fan would surely just accelerate or intensify warping?
The machine still needs a way to circulate the air and make sure that the heat in the chamber is consistent.
Even with the fan on (when it is set to heating) does not lower the chamber temp.
Warping is the only reason to turn it off.
Someone making a mistake.
With the Bambu Preset filaments, the machine does not switch back to cooling, but it does it on the generic presets for some reason.
Best to just make your own custom filament profiles for everything that is not Bambu.
BTW, most of the ABS and ASA that I use is polymaker and they have filament profiles for download on thier website, makes it really easy.
Of course the aux fan won’t lower the chamber temp, but it will increase warping, hence it should be off. With it off, more heat from convection and radiation from the build plate will transmit to the model, making a more feathered heat gradient in the model resulting in less warping.
So, when choosing ASA in Bambu Studio, the g-code should turn off the aux fan for the best printing result. Which is why I don’t understand why Bambu has made machine code that activates aux fan when printing ASA.
Because you need to understand how the system works.
Warping is mitigated because the fan outlet is coming mostly from the outlet that is below the heat bed when the bed position is at the top.
This is not true. You are going to get a similar amount of heat going into the model. But without proper air circulation you are going to get more shrinkage on the rest of the model.
This is not true. You are going to get a similar amount of heat going into the model. But without proper air circulation you are going to get more shrinkage on the rest of the model.
This does not make sense to me. What part of the material’s rheology or polymer physics make it shrink less with air circulation?
Without air circulation, the model will get hotter due to the heat from the build plate radiating and rising upwards. It’s only when styren polymers cool down, that they shrink. Which is why you want as much heat in and around the model as possible during printing.
Air movement increases heat transfer
Without air movement, you are not apply the radiant heat from the bed to the rest of the part (only the part that is closest to the heat bed)