PLA print with PETG Support Interface and insane Print Times

[Nox1]

tl;dr: Using PETG (or any other filament) for my Support Interface more than quadruples the printing time. What am I missing? Support Settings at the bottom.

Hello everyone!

New Print-Owner here, a Bambu A1.

After it has been recommended to me, I got my hands on some PETG (Sunlu) I could use for the Support Interface - with the intention of making the removal of said support easier and clean.

So, select my default filament for the Support/raft base and the PETG for the Support/raft interface and I’m good to go, right? Well…not exactly…

I expected an increase in print time, of course. The ASM having to switch filament takes time, so naturally it will take longer. What I did not expect was this:

Good God, what is going on here? Three days for the Prime tower? Almost 0,5kg of Filament for a 12cm tall Miniature? So I disabled the Prime tower, and sure enough:

Uhm - It doesn’t really change all that much. Instead it just takes two days for the Outer Walls now. Maybe I’m too aggressive with the Support Placement?

This is the model in question:

Granted, that’s a lot of support and I could (probably should and will) optimize it by painting the supports instead of automatically generating them.

But then I tried another model:

It uses a ton of support as well, but it’s print time is much more reasonable at “only” 17 hours. Now I print at a high quality setting, 0.06 Layer height with a 0,2 Nozzle - Slow prints are to be expected.

Without separate Interface Filament, the print time jumps down to roughly 24ish hours - Which is fine by me, considering the size and quality.

To make a long story short - Is there something I’m missing? PETG Interface Support for PLA prints has been praised everywhere I looked, and while I’m very patient - more than FOUR-FIVE times the print time and 10 times the material? This can’t be right.

Here are my Support Settings:

EDIT: I uploaded the wrong picture, here are the real settings, sitting at over 5 days and almost 500g of Filament.

[Square3D]

The problem i see with your settings, atleast if i am not mistaken, is that you are using petg for the full support when in reality you should only use it at the interface part.
In your support settings change the option “Support/raft interface” from default to your petg filament. Then you use the same pla for both the model and supports. That way petg is only extruded between the most top layers of the support, reducing print time, petg waste and long hours of filament change.

[Nox1]

Ah damn, I have attached the wrong screenshots…My bad! I will edit my original post. Unfortunately I already have set it to “PETG” whereas the Raft Base is set to Default. With them both set to PETG, it jumps to an absurd 8 days.

Honestly - It’s not even about the time. If it gives me the best possible results but takes a day or so? So be it. But 500+ Grams of Filament just gone, for a Model that is 70g tops? Something weird is going on.

Out of curiosity, I tried a much less complex model:

That Miniature is scaled to less than 43mm, and even then it would take a staggering 19 hours of print time.

[Neiljt]

There is a lot of excess travel time for what is essentially 10 mins of petg printing
if it adheres to the pla

[Nox1]

Yep, it seems odd. It almost looks like whatever is inflating the print time is just, for lack of a better word, moving from place to place. If it’s not the Prime Tower, it’s the Outer Walls. If it’s not the Outer Walls, it’s the Travel Time.

[Neiljt]

You could try moving the prime tower closer to the model and adjusting the size but personally id stick with one material for what the petg print time is worth

[Square3D]

Are any of those models available to download? I would like to try and slice them myself with your aproximate settings and that PETG interface.

Maybe is something messing with the slice or maybe it’s the model itself.

[Nox1]

Thanks! They are available for free at Maker World. The Tiefling / Demon Mini is part of this collection:

DnD Player Character pack2 miniatures Remixed by Darkwing

The other one was available on Makerworld too, but I can’t find it anymore.

@Neiljt If I can’t find a way to fix it, I’ll definitely have to improvise. Not because of the insane print time, but because of the wasted material. 500g of Filament for a 40mm is Games-Workshop Levels of insanity.

[Square3D]

Well, a quick slice with the above model showed only a few hours print time, even with PETG support interface, 0.2 Nozzle with 0.08 layer lines.

I didn’t touch the scale, left it as it was.

[Neiljt]

This is a 5:30hr petg print until i add pla (green) as a interface

primarily a basic model with auto normal supports

[Nox1]

Amazing, thank you!

I just tried to re-create the settings.It seems that the Top Z Distance is to blame.

If set to 0.1, I get similar results to you.

But if I set Top Z Distance to 0, without changing anything else:

Oddly enough, Bottom Z Distance doesn’t cause any trouble when set to 0, which is kinda weird.

To make things even more confusing, the only reason I set it to 0 in the first place, was because the Support Guide for Bambu Lab specifically states:

When the filament of the support interface is a kind of support filaments, such as Bambu Support for PLA, Bambu Support for PLA/PETG, Bambu Support for PA/PET or etc., the top Z distance can be set to be 0.

You think this is intentional, or is there a bug in the Slicer that’s causing the trouble? I can’t imagine that an almost 16 hour increase in print time is working as intended.

It also seems that this only fixes the issue for the “Default” Tree Supports…Tree Slim Support is still sitting at more than a day, despite unchanged Z-Distance:

[Square3D]

I am glad you figured it out and that i could help somehow. Happy printing

Edit: tree (default) should be enough. I would try with that

[Nox1]

Do you think that Default will be enough? It seems to have so little Support Interface by comparison, I’m worried that it might make the supports fairly hard to remove.I’m gonna give it a try though and keep searching, maybe I’ll find something

[Square3D]

I can only tell from my experience. But usually even with PLA supports on PLA parts i get a pretty decent outcome. Supports come easy and leave almost no marks

[Nox1]

Okay, just gave it a try - Unfortunately it did not work out Most of the support wasn’t using an Interface at all it seems, so the support was very difficult to remove on a small print.

I changed the angle of the Mini:

Now I get much better Support - Support that would make it easy to remove it and have a clean Mini. But as you can see, the Printing Time and Material Cost is just as insane as before. So it’s not linked to the Z Distance after all it seems.

I know that printing with a 0.2 Nozzle at 0.06 Layer Height will drastically increase the Print Time I expected 2-3 more hours. Maybe 4-5, heck even 6. But 20? And 10 times the Material? I can’t help but feel like something is still off and I’m missing something…

For instance, these are the print stats without PETG Support Interface, but the same quality:

That’s 5grams of Filament vs 100 Grams, and 20 hours more. It’s insane.

[Anthony1710]

Hi did you find a solution to this, I am having the same problem. Changing just the support/raft interface to support for pla/petg filament. Turns the 2 1/2 hour print without changing filaments to 1 day plus when changing. Just the support/raft.