Weird wrong filament used problem with multi color PLA/PETG print

I’ve encountered a weird problem when trying to do a multi color PLA print, with PETG as the support interface.

The print uses 2 PLA colors, green and gold, starting with green and then switching to gold at a certain layer height. I’m using green as the support base and a PETG filament for the support interface.

Initially, the filaments were loaded in the AMS in this sequence:
1: pink PLA
3: gold PLA
4: green PLA

The AMS sequence, type of filament and color matched the one in Bambu Studio, in the “Prepare” Filament tab, as well as in the “Send print job to” pop up.

The problem I had was that the printer would pull in and start to print with the GOLD PLA, rather than the GREEN PLA.

I then did some troubleshooting and found that the correct, GREEN PLA is used if I don’t use the PETG for support, ie by changing the support interface to default.

I then swapped the filaments in the AMS so that PETG is the “last” filament, ie in slot 4, and reassigned the colors again to match (ie. green for the bottom layers of the print, then gold, using PETG as the support interface):

1: pink PLA
2: green PLA
3: gold PLA

It now seems to print correctly, ie using the GREEN PLA to start with.

Any idea what could cause this issue, and why swapping the filaments would fix it?

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There were ssome wierd issues with Bambu Slicer versions and stuff being fixed, what version are you running atm?

  • Some of those issues were Support interface related, getting it out of sequnce or using interface material for model material etc etc.
  • Some of it was on the GitHub etc, I cant find the Github post right now.

Similar post … where I tested the different slicer versions etc

Not sure if above is 100% related to your issue, but seems similar and with wierd code in the slicer could be causing similar issue.

Loading order, poor code with incorrect logic etc, unsure without more info and more testing.
I presume the PLATE’s Filament layer sequence order is correct as well between filament changes, but if itss on Auto the AMS and Send and other factors are all lined up - it should figure it out.

Thanks DruiD for your input.

I’m using Beta, so hopefully any bugfixes relating to this would have been included.
Re support interface issues, the gold PLA it picked to print first is neither selected as the support base (green), nor the support interface (PETG).

Thanks for sharing the link, unfortunately I can’t access it (says doesn’t exist or is private?)

I had also tried changing the first and other layer filament sequence, but it didn’t make a difference.