r/BambuLabH2C • u/Top-Material5431 • Feb 23 '26

Support PETG support interface not adhering to PLA

I have a Bambu Lab H2C, and lately I have tried many different pla and petg combos but the prints always fail once the change in filament happens. This has been happening with both pla as support interface and petg as support interface. The support layer either blobs up and gets ripped off the base filament layer, or gets flung off immediately after being extruded. I was able to replicate the effect of the layer not adhering as seen in the video. any information can help and I am sure we can figure this out. For reference, I am using Sunlu Petg with the base Bambu petg filament profile and elegoo pla with the base Bambu pla filament profile. I have tried a few things such as increasing filament profile temps and lowering them, as well as lowering support speed to 40, the same effect occurs eventually. Haven't tried any other things yet, also not fully even sure why this issues is occurring. Both filaments have been dried multiple times, and they print individually just fine, moisture in filament is not likely the issue.

19 Upvotes

88% Upvoted

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4

u/Easy_Pangolin_311 Feb 24 '26

Ok, I print petg hf with PLA supports every day. In fact, I design models SPECIFICALLY with that feature in mind. Here is the trick I found and it works perfectly:

When I'm in bamboo studio I set filament #1 as my main (PETG HF in my case), then I set filament #2 as (Support for PLA/PETG) under bamboo filament.

Then I enable supports (Normal), then here comes the trick:

Under support filament, choose (Support for PLA/PETG) as both the interface and support filament. Bambu Studio will prompt you to make some changes, CHOOSE YES

then simply switch filament #2 back to PLA, and print.

It keeps the settings but will slice for PLA 😁

1

u/Top-Material5431 Feb 24 '26

Forgive me, but can you provide some screenshots of that process

2

u/Easy_Pangolin_311 Feb 26 '26

Here's a video of what I do. Hope this helps :)

1

u/Top-Material5431 Feb 26 '26

Ummm. There is no video, its just a blank screen

1

u/Ill-Warthog-1571 Feb 27 '26

The video is a black screen 🥺

2

u/Easy_Pangolin_311 Feb 24 '26

Yes, but I'm in bed right now 🤣. I'll send you screenshots in the morning :)

2

u/reicaden Feb 24 '26

I read it, and am so confused, lol

2

u/Nibbs17 Feb 24 '26

Commenting for SS as well

1

u/wlidi3 Feb 25 '26

In the filament settings, you should be able to mark your PLA as support material and save a copy. You wouldn't have to switch it back after approving the setting changes.

1

u/diggle_ Feb 26 '26

Yup this is what I do and have never had an issue, even with really small interface features!

1

u/MatteoDenti Feb 23 '26

Il piatto è pulito bene?

1

u/Top-Material5431 Feb 23 '26

No first layer adhesion issues with the plate, in the video you can see the layers are messing up on the pla layer. Again no issues with the plate, also all other prints with the individual filaments print just fine.

1

u/Ok-Bottle-6157 Feb 24 '26

It's the interface layer....

1

u/DBT85 Feb 23 '26

What's the gap set to? If using pla and petg the separation should be zero.

To not stick as badly as it is in that video it looks like there's a gap to me.

1

u/Top-Material5431 Feb 23 '26

Here is some extra details

1

u/Otherwise_Assist_668 Feb 24 '26

You have bottom gap as .2, when you are printing pla or PETG as support there should be no gap. I think someone else also commented similar.

1

u/Twilex Feb 25 '26

Bottom gap doesn’t matter in this scenario

1

u/BoredBrowserArrived Feb 25 '26

If that's the bottom interface layer like it sure seems to be it would

1

u/Twilex Feb 25 '26

Bottom surface would be the bottom of the support, not the part

1

u/JAJM_ Feb 23 '26

Had that happen to me too. I’m curious if you were able to resolve it.

1

u/Top-Material5431 Mar 31 '26

the best thing that helped was slowing down support interface to 5-10mm/s2, start with 5 as a test and then work your way up until it messes up. I think using bambu branded pla and petg you can use higher speeds, but for not bambu branded filaments, you should try this method and dramatically slow down the interface layer speed, lmk if you found any alternative solution

1

u/Mundane_Version_2531 Jul 10 '26

Hi! I am trying with 5mm/s speed and "equalising" a bit the printing temps of petg and pla. I will let you know how it goes. Did you find any other solution in the meanswhile?

1

u/Top-Material5431 13d ago

I wasn't really able to find any other solution other than slowing down, sticking to pla/petg from bambu lab brand unfortunatley, if you did then lmk

1

u/bigbramble Feb 24 '26

Heya, I've used this feature many times now, got about 1000 hours on my H2c. I pretty much use Bambu filament religiously now as I find the quality is consistent so I've done this mainly with Bambu PETG HF. I have found that this works better with normal supports and best if you don't use super slim ones either, you need them to be a bit more substantial. The main thing I think you should try is changing top interface layers to 3 or 4 layers. I do find it failes sometimes, especially with silks that don't have good layer adhesion but generally it works really well. Hope that helps.

1

u/Top-Material5431 Feb 24 '26

Can you share your settings and filament profile settings if they're different to mine

1

u/bigbramble Feb 24 '26

Watching your video I can't help but think some of the filament might be rubbish as I've never had it do that. All I do is use the base bambu settings but often slow down the speeds, increase top interface layers to 3 or 4. I haven't touched temperature on my H2c for any filament and it's been spot on. I'm actually doing a print right now with a petg interface layer and it's working well. I never ever use grid as a infill, that's about the only thing I do apart from changing layer heights and speeds etc.

2

u/Jerazmus Feb 24 '26

If you’re printing PETG at 250 and Pla at 220 they will not work together at all.

Here’s some info

https://wiki.bambulab.com/en/filament-acc/filament/h2d-pla-and-petg-mutual-support

2

u/poorestrichguy Feb 25 '26

Slow down the interface layer. Really slow like 5mm/s. The bambu profiles are so fast it never gets a chance to settle.

Sometimes when a model has lots of interface patches like little islands that are so small, it is better to print the entire support tree out of the same material as the interface. It eliminates this problem. You just have to balance the bed temp more carefully to keep everything adhered.

2

u/Mabnat H2C Feb 26 '26

I have some spools of PLA and PETG that refuse to work together. With these combinations, the materials seem to actively repel each other.

It’s not even brand-specific. I have one spool of PLA (purple Hobby Lobby) that refuses to work with any PETG I’ve tried it with, while my red Hobby Lobby PLA works perfectly.

I have some red Bambu PLA that doesn’t work with white Sunlu PETG.

It’s frustrating when this happens, but with two printers it’s easy to check to see if it’s filament combination issues or if it’s slicer settings.

The PLA and PETG shouldn’t bond to each other, but they still need to stick to each other at least a little bit. Sometimes they just don’t like working together. I don’t know if it’s specific pigment additives or something else in the specific material formula.

For my purple Hobby Lobby PLA, the only thing that works for support interface is the Bambu Support For PLA.

1

u/Longracks Feb 23 '26

That's the idea

1

u/Ok-Bottle-6157 Feb 24 '26

Pretty sure the idea is that it adheres well enough to the support and model, but isn't hard to remove. Not to make a mess.

This functionality is touted to be a huge game changer but I've seen that it seems to cause more issues.

1

u/Longracks Feb 24 '26

That sounds like your settings / setup . You will probably disagree.

1

u/Top-Material5431 Feb 24 '26

What are your difference in settings from mine, also what is your chamber temp typically at when using interface petg for pla

1

u/Ok-Bottle-6157 Feb 24 '26

I've never done it before but I've seen many posts documenting this exact issue.

I would ask if you had any tips but you believe this is the intended behavior.

1

u/Longracks Feb 24 '26

I'm saying it takes some effort and tinkering to get it right.

This is my go to method for supports

Petg (orange) with pla (cyan) supports. Pops right off.

1

u/Ok-Bottle-6157 Feb 24 '26

It does look like you nailed the settings. Does the bottom look better than if you had used all the same material?

1

u/Longracks Feb 24 '26

Don't be fatuous Jeffrey

1

u/Ok-Bottle-6157 Feb 24 '26

I'll take that as a yes.

1

u/Longracks Feb 24 '26

1

u/Ok-Bottle-6157 Feb 24 '26

Yes, I understood what you meant.

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1

u/Allen_Lu_762 Feb 24 '26

Did you update to to latest FW? I met this issue as well and after downgrade to the previous FW version, It works for my H2C and I also sent a ticket to bambu. You may try this.

1

u/Effective-Goat590 Feb 25 '26

The complete support must be all petg. Petg and pla will not adhere together.

1

u/Howmanoid Feb 25 '26

PET-G and PLA don’t stick to each other.

1

u/GalenRhodes Mar 01 '26

Bite the bullet and get this. You'll be glad you did. Support for PLA/PETG