This is a multipart issue.
I managed to get eSUN PETG+ print via the main nozzle on a Bambu X2D. Still have some challenges on wall splitting on large models, however for small models it seem to be work reasonably well. Trouble started when print a larger flat models using PLA (eSUN PLA+) as the support interface on larger models. The PLA was being printed via the Auxiliary nozzle. I experience some serious warping issues, starting at the point where the PLA interface was being printed. I noticed that the PLA profile (using the Generic PLA profile) was ramping up the auxillary parts fan and auxillary nozzle cooling fan, most likely over cooling the warm PETG causing the warp. I did the following, step by step to see what would improve the warping issue:
On the PLA profile turn up the bed temperature to match the PETG bed temp of 75 degrees (C). This result in minor improvement.
Again on the PLA profile change the auxiliary parts fan form 70% → 0%. This result in more improvement, however did not eliminate the issue.
Added a skirt of sever layers. No real improvement.
Changed the part cooling fans in the support PLA to match that of the PETG. So maximum 100%→ 60%.
Never got see the result here and this where things started to horribly wrong. I noticed that the Generic PLA profile has a max temp of 250 degrees (C), way to high for this filament. I also noticed that this temperature on the Auxillary nozzle was set to maximum (250) at the beginning of the print, even though the interface layers are required one hour into the print. Once it PLA interface layers was supposed to print, nothing was extruded except for a few burnt bubbles. The print failed.
Troubleshooting revealed that the auxillary hotend was generally clear but did have hardended burnt looking “bits” baked on to the tip. However the “pre-hotent” section (is that what its called?) , the part where the bowden tube is connected, was totally clogged. Cold pull did not work, instead the filament broke and was left with a semi-molten plug of filament in this part, (see image of part). I fairly certain that this should not have happened. There seems to be no safe way of cleaning this part out without causing damage. I contacted Bambu Lab support, who are kindly sending me a replacement - thank you. However their explanation of how this happened is not possible. My guess is that the nozzle over heated and the molten PLA bubbled its way into this section because the auxiliary hotend was heated at 250 degree for an hour.
Thanks for you reply, It may help to prevent the model pulling and warping at the build plate. The PLA was being deposited well enough on the the PETG support and the the PETG layers were not warping from the PLA interface layer.
This may not solve the issue of the over cook PLA and clogging right hot-end delivery section.
Some of my ideas are to reduce the maximum possible PLA temp from 250 to 230 degrees in the filament section. The other was to raise the vitrification temp for PLA to influence the fan speed.
At any case, I will have a look at the M142 command and the code to see what it is actually trying to do
Bambu support kindly supplied a new fillament senor block and a rights nozzle heater unit. I managed to reassemble the head, (on a side note, follow the Bambu disassembly/assembly videos exactly, order of assembly is important). I now have a fully functional tool head on the X2d and all test and calibrations passed.
Printing test on the left (main) nozzle for PLA and PETG were successful. PLA printing test on the right nozzle where also as expected.
However….. Printing PETG with PLA as the support exhibited same issue again. It seem that Axilliary (left and right) fan control via the slice is non-existant, ie fans doing what ever they want, and the right nozzle temperature control is also being ignored, again doing whatever it wants and not what the filament calibrated profile is configured to. I will be including a series of screen shots and config settings in the next post.
As another aside, Bambu support suggested that my tool head failures where due to bed adhesion issues. This is clearly not the case - it seems to very much a combination of overridden fan control by most likely by the firmware and perplexing temperature controls of the right nozzle.
I have not had any issues using PLA as a support interface for PETG.However, I use a fan deflector/diffuser so the fan does not blow directly on the print. The upstream V2 version of this diffuser is what I use. I combined it with the left deflector from the same maker.
All this is primarily done using Orcaslicer 2.4.2, on Linux. I generally do not use Bambu Studio as my may slicer as it simply does not have some of the functionality that I use, however tests show that the behavior seems largely the same.
Parameters:
Main Fillament
eSUN PETG+ clear used on slot 1 on the AMS2 and set for the left (main) nozzle.
Printing nozzle temp: 245 (248 first layer)
Bed temp: 75 (80 first layer)
Part cooling fan: - max 60% - min 30%
Auxiliary Part Cooling Fan: 0%
Support Filament:
eSun PLA+HS (calibrated of the right nozzle and adjusted to work specifically as a support fo PETG, so cooling and bed temperature values changed to values shown bellow but nozzle temperatures set for PLA
Printing nozzle temp: 220
Bed temp: 75
Part cooling fan: max 100% - min 80%
Auxiliary Part Cooling Fan: 20%
Issue 1 (See image1)
When the print starts on PetG, the right nozzle temperature is set to 248 - the max printing temp of PETG, not PLA. For some reason, the right nozzle is assuming the temperature of the PETG.
Auxiliary fans are on 60% and parts on 50%. As far as I configured, the Auxiliary fans should be lower or even off.
I can so no reason to keep PLA nozzle temp or a loaded nozzle at 248. Especially with a longer print, this will cook the PLA in the right nozzle for a long period of time. This situation is what i think damaged the right nozzle. This probably should be kept warm (140?) until the system runs a quick flush at the point of using it. The last sensor block was filled with burnt PLA and could not be cleaned and required replacement.
This is as the point the right nozzle was printings its first layer support structure, after the wipe tower.
The left auxiliary fan is the 20%, lower than the PETG print, but as I set it via the filament profile. However the right auxiliary fan is at 50%, no sure how that gets there, however it may have something to do with chamber temperature control.
The PAL nozzle temperature is now at 210, not at 220 as set in the filament profile.
The left Auxillary fan appears to be where it has been configured. The right fan, doing its own thing, again possibly for chamber temperature control.
The right nozzle temperature is now stuck at 210, why? It should be at 220 while printing. It remains at 210 for the remainder of the print, well after the interface layers have been completed. It seems the heater should be shut of at this stage.
The bottom right is block is scrappy, possibly due to adhesion issue, as I do touch the build plate around that area. I have the air baffles in places.
I will see if they work on a large model.
What I am most concerned with is overheated the PLA in the right nozzle again as it seem the temperature control for the interface layers seems to do its own thing and not what the filament profile tells it to do.
I had a quick look at the exported GCODE and see no obvious reference to right nozzle temperature other what I set.
I alos looked at the multimaterial settings and multi extruder setting in Orca slicer. I set those to match the X2D as far as I can see. This also made not difference.
I will attempt to print the same using Bambu Studio.
I really would try using Bambu studio. Orca slicer has been nothing but pain for me. There are still too many issues with newer Bambu printers (like unable to control aux fan). Also the default profiles print worse quality for some reason. Even though the settings are largely the same to Bambu studio.
As for how to print PLA supports. One trick is to disable both aux fan. Then keep your chamber cool by opening the door and/or top glass instead. The main culprit of PETG warping is the aux fan blowing cold air directly on the part. Opening the door will keep your chamber cool without too much air going over your part.
Also the next behavior demonstrated with keeping the nozzle hot till the end makes no sense at all.
This could explain several clogs/heat creeps already reported in the forum. As this active cooled box should not be so easy to creep. But if it does this random stuff then it absolutely makes sense to get in trouble. And this could be a clear trace for vibe coding in the firmware…
I also had a good fight with the fans, and their behavior and if you go and manual stop them while printing, then they behave a bit differently.
Maybe I can load some petg and pla later tonight and try to recreate this behavior.
What I did before was PLA on main and PETG on aux, and it was disaster many times, but as long as I remember the nozzles was cooled down in between changes.
More and more looks to me that multilateral printing on X2D is really a edge case, and the main usage is for same material prints, or material + special support material. And rare engineering single color stuff.
Hello, I resolved the adhesion issue in the front-right corner by adjusting the “First Layer Calibration” for the left nozzle by -0.04; the first layer now adheres flawlessly across the entire print bed.
At this stage I will state that the right nozzle temperature issue seems to primarily a Orcaslicer problem. I have not managed to recreate the issue with the latest stable BambuStudio version.
The fan control is however another story. I think we would like to understand how the fan control algorithm actually works - seem so random. So it tride the following step by step:
Change fan settings for the filament → made no difference
Increased Bed temperature and slowed down first layer. → Improvement in overall adhesion, but minimal warping improvement
Use Bambu Build Plate Glue → That help overall adhesion but not the warping.
Print a mouse ears (Orcaslicer, did not find it in Bambu Studio) → no difference, PETG still warped.
Use a Brim → minimal difference on model more centrally place on the build plate. No difference on models that covered the edges of the build plate.
Used a Skirt of 5 layers high → Some improvement. However if the skirt came off the plate, it flapped around in the air flow and made a bit of a mess. The fact that I could see the skirt be blown around was a good indicator that high air flow was the possible culprit.
Printed PetG air baffles for both left and right vents, the right vent was only a slight 20 degree upward direction, left was 45 degrees. → Vast improvement, no warping on the left side of the model, however mild warping still present on the right
Replaced the baffle on the right with a 45 degree unit. → no more warping.
For larger flat models, I use a brim and a skirt of 5+ layers. The air baffles seem to do the most of the PETG warping prevention. I now have the best PETG prints I have ever made, and using standard PLA as a support interface.
(BTW, I added to a Orcaslicer bug report for the auxiliary nozzle temperature control - I found I was not the only one)
