Advice for smoother material changes?

Not sure if it is specifically the left nozzle, or just because I typically print various materials with the left nozzle, but it seems when I switch between different temp materials, it just leads to temporary jams/clogs.

Generally I print in ABS, but every once in a while I will print PETG (standard and clear), and PLA. After printing in one of those, when I go back to ABS, I tend to have problems.

Anyone else seeing this issue, and are there any extra steps you take to transition a little smoother? Looking forward to finishing my StealthChanger build so I can just dedicate toolheads to specific materials.

I wonder if getting more of your old filament out would prevent it from being purged at the new filaments temperature. Perhaps this is causing clogs. There is a beta option for longer retractions on cut, I’ve not played around with it, but I’ve wondered if that could help with situations like this.

The cold pull function in the toolbox menu will likely help you out in these scenarios.

It is quite known that switching to low temperature filaments when coming from filaments that have a high chamber temperature, you might get clogging.

But the latest firmware warns you when you try to load PLA in a chamber hotter than 40C.

I also notice that during the changing of the filament, the printer is using the temperature of the previous filament to make sure that old filament can be purged. So far I have not had any clogging due to that.

Do you see the nozzle go to the printing temperature of ABS when it changes to the lower temperature filament?

I’ve noticed this, but brushed it off. It was when I went from PLA/PETG to ABS and I started warming the chamber. I initially thought it was a mistake, not thinking about the filament bit still in the hotend. Maybe my workflow is the cause. Usually when I know I’m about to print something in ABS, I’ll manually start the bed/chamber warming, so by the time I’m ready to hit print, it is almost or completely warmed up.

Yep, that seems likely to be the cause. With a chamber temperature of 60-65C your cool end of the nozzle reaches the same temperature. PLA specifically is already almost fluid at that temperature and easily clogging your nozzle.

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So before I set the temps, would it be best to manually run the “Load” step for the new material? I imagine the printer will know the best way to purge the old material, and prime the new?

I have been running several jobs with ABS or ASA after a PLA job, but so far that has always been on the external spool to be honest.
Might have had some where it was in the AMS, but usually the printer already swapped out the filament far before the chamber was at 60/65C.

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With my H2D because nozzle swapping is fairly easy i’m going to try and keep completely separate nozzles for different material types.

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That is also a possibility. But my advice would be to run the “High-precision nozzle offset calibration” when you will be running dual color jobs.

Looks like that only works with PLA according to this thread. Might try it though anyway to see if I can tell the difference with 0.2mm prints

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That can indeed be an issue.

this calibration only works in XY plane so don’t worry too much (if, you have some pla stock).

According to the support:

  • High Precision Nozzle Offset Calibration only works for XY plane.
  • Z offset is done by probing the bed.
  • XY offset can also be calibrated using the nozzle offset sensor on the heatbed. However it’s not as accurate as the high precision one. But I believe it should be good enough for most prints.

Anybody ever have to do cold pulls on the x1c, p1s or a1? I did not.

I had on my P1S a while back. I was adapting cardboard spools to bambu’s ones frequently, so I think it was a piece of cardboard in mine

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