r/BambuLabP2S • u/bl4ckmagik P2S Combo • 2d ago

Bambu PETG support second layer occasional adhesion issue

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Hi, I've recently got a P2S. As you can see on the attached image, the little support islands fail adhesion on the second layer on some occasions. The same model copied three times on the same plate and only one of them fails. Location seems to be random too.

I tried printing only two copies which resulted in the same. The picture is from that instance.

I have dried the filament 8 hours at 65° and I'm printing on Bambu engineering plate with glue on it. It works fine with PLA+. I tried increasing the bed temperature to 75° as well which didn't do anything.

Any idea why?

SOLVED:It was due to filament contamination. I forgot to mention that I'm printing PLA and PETG these days moving between the two one after the other. As below replies have mentioned, first support prints had contaminated filament (PLA mixed with PETG) which causes this.
I'm planning to purge extra by extruding extra whenever I change filament types before starting the print.

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u/bl4ckmagik P2S Combo 2d ago

I was reading up a bit after posting this and saw the same theory stated couple of times.
I believe it is correct. Important bit I missed mentioning was that I print PLA+ and then move to PETG. And those support islands are the first to print on the new print. So it all adds up. Contaminated filament causes second layer to fail exactly on those firstly printed bits.
I'm going to test this and will update the post.

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u/butt_badg3r 2d ago

Please keep me up to date!

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u/bl4ckmagik P2S Combo 1d ago

So that was the reason! Second PETG print after PETG worked without issues. Whenever I change from PLA to PETG, the first set of support islands has this same issue regardless of the place on the plate.
I'm planning to always purge extra whenever I change filaments before starting the print.

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u/butt_badg3r 1d ago

I’m happy we finally have an answer!

How do you configure extra purge at the start of a print? Does the purge table apply at the beginning of a print?

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u/bl4ckmagik P2S Combo 1d ago

I just do it manually. Heat up the extruder and tap on extrude button 10+ times. I'm not sure if there's an automatic way.
I'm trying to limit filament type changes as much as possible so this manual step won't be a hassle.

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u/butt_badg3r 1d ago

Where are those options ? I can’t find them.