H2D - PETG does not adhere to PLA support

Bambu Lab H2 Series Bambu Lab H2D
1

I am trying to print PETG HF with PLA Basic as support interface (only interface, base support is PETG). I am following the wiki guide Printing guide for using PLA Basic and PETG HF for support and their profile PLA Basic supports PETG HF.3mf

The problem - PETG HF does not adhere at all to PLA Basic interface layer (attached photos below). Both are brand new and dried for 12 hours after unpacking. PETG humidity <10%. PETG and PLA both print separately flawlessly with 0 defects. Also PLA adheres to PETG just fine.
Speed is set by “Balanced Quality” profile and is already quite low.

The body has 90 degree angles and PETG needs to adhere to PLA, it cannot simply pass over lying flat on top of PLA layer. I wonder if this is possible at all or I do something wrong.
Please advise. Thank you.

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PETG model print with PLA support interface, Extruder overload when loading PLA
2

I’ve never had luck with this combination either. I think it only works in specific geometric instances…

3

Thanks for sharing this.
I am afraid there’s a chance that it’s not possible, even Bambu examples show only supports for straight lines. Moreover, many people posted similar experience with special support filament for PLA/PETG.
However, I still hope that someone found a way to make it work. I want to try to increase PETG temperature a bit and set Top Z Distance to -0.1 instead of 0. If PLA interface adheres to PETG, there should be a way how to make it work working vice versa.

4

Just to clarify - when you print the model in PLA, using PETG as support interface, everything works OK?

The issue is only when you print the model in PETG, and use PLA as the support interface?

5

Can you show a photo of the model sliced with “line type” setting enabled to show where the supports should go. I can’t visualise it or how this is failing.

6

After trying different settings and manually testing PETG adhesion to PLA, I can certainly say that printing PETG 90 degree angles on top of PLA is not possible with the current BambuStudio. There should be a separate settings subsection specifically for the first layer on top of a support to make it possible.

Bambu examples and public promo videos show only straight overhangs laying on top of support structure, that can be easily done as it doesn’t require adhesion. However, 90 angle requires the filament to stick to the support structure, in current case PETG to PLA which is not possible. If BambuStudio could provide a fine tuning for the first layer on top support, it would be possible to slow down the extruder and change the temperature.

7

Try white PLA as support material. I had in the past issues also, until I switched to light colored support material.

Using white or light grey ever since, without any problems. It should be dry also. I know you dried it, but you might try another cycle on that

8

If you search for the discussions on this subject you will find that everyone states “PLA does not work as support for PETG”. BambuStudio needs to include fine tuning settings for the first layer over the support material in order to find a workaround. This could provide a workaround to lay down PETG straight over PLA even with sharp angles.

9

I guess I found a workaround solution for this problem - you need to add 1-2mm PETG cylinder anchors for each corner, this keeps the lines straight and solves the problem.

1 Like
10

The support interface speed is reduced to 20mm/s, which can significantly improve…

11

It’s so disappointing to see that the most replies come from the paid spammers who never 3d printed anything.

1 Like
12

You’ve got 5 responses on your post.

So I may assume you’re referring to at least 3 of them as being paid spammers?

Yes! You find a lot of people that can’t get it to work. And yes, it can sometimes be hard to get it to work, and wet filament is usually the cause.

But that doesn’t mean nobody gets it to work. Keep in mind that most of the people that have no issues with it, are not coming here to tell how good their job went.

EDIT: read this statement: Support material for PLA/PETG not sticking - #46 by Poporacer

I had to fine tune sometimes, but I printed organic parts where islands of PETG appeared on PLA supports that eventually joined the main part.

The fact you come up with a solution yourself, contradicts your own statement.

Additionally, when I look at your first image, you have some things you might want to focus on:

  • The first layer looks pretty weird, as if there is no proper adhesion to the plate and the Z-offset is too large.
  • Your top layer looks like the infill lines are not really properly bonded to each other.
  • The top interface layer doesn’t really look very smooth. Is your flow rate properly calibrated there?
2 Likes
13

I’m not sure what everyone else states, but in my experience, PETG printing with PLA support is no problem. And I’m talking about a relatively large print (a riser for my P1S) with a unbelievable & huge amount of supports - it wasn’t my model and it was designed so that support was needed almost all around the riser body.

It worked perfectly for me… without the PLAxPETG combo, I can’t even imagine printing it (or rather, I can imagine printing it, but not removing the supports).

TW

14

I can perfectly assure you that printing PLA with PETG supports works fine, but haven’t tried the opposite.

15

Thats what I will be doing anyways - PLA with PETG support - so works for me! Just need to get my Vortek upgrade finished first!

16

Instead of using an interface layer I do the full supports from the secondary material. The print time is increased but there are no problems with complex shapes.

2 Likes
17

And also that makes the part look better most of the time, due to reduced layer time changes

18

Due to the chemistry and material properties, PLA can wet PETG with no problem, therefore PLA over PETG adhesion works well. Vice versa, PETG cannot wet PLA and doesn’t stick to it.

Bambu support needs to fix their Printing guide for using PLA Basic and PETG HF/PETG Baisc for support | Bambu Lab Wiki . “Filament combination” part with the temperature tables contradicts the detailed guide with the screenshots - the nozzle and bed temperatures are completely different:
PETG as support for PLA: 1) Table nozzle temp PLA 220 PETG HF 230, 2) Guide PLA 230 PETG HF 265
PLA as support for PETG: 1) Table nozzle temp PLA 245 PETG HF 245, 2) Guide PLA 230 PETG HF unchanged (245)
The actual recommended temps are not clear.

and minor typos like “Baisc”