Support Filament --> PETG for PLA and PLA for PETG and more

Bambu Filament and Accesories
63

Do you just put this code at the beginning of the ‘Machine gcode’ block? LIke so?

image

I am able to use PLA as support for PETG on my .4 nozzle, but having a heck of a time getting it to work on my .2 nozzle. It seems to clog. I am using 800 both ways for flush volume, and now trying this higher temperature for flushing.

It seems to clog on the switch from PETG to PLA, my theory is that it lowers the temp to PLA (220) to soon and the PETG solidifies and clogs. When things go wrong I get a "Failed to fee the filament into the toolhead’. I then do a manual purge/cold pull, etc. and start over.

Things are very slow to cycle through these experiments. This last time my extruder got completely jammed. Lucky I have a spare and I get to learn how to clear the jam/clogged extruder!

64

You probably need to adjust the max temperature of PLA to PETG. This should be the temperature used for rinsing. 240°C should be sufficient.

65

It should be an upgrade to their printers!

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66

It’s worse than that, Bambu actually deliberately drops the temperature to 220c when changing with PETG in the ‘filament change’ section of the g-code - it caused me no end of issues when I was using PET-G along with nylon for a part I couldn’t work out why it would randomly drop the temperature and clog solid.

I do love settings that completely ignore user input hidden away in the g-code, very useful :slight_smile:

1 Like
67

Yep, I wrote about that in January.
Happily purging PETG @220c, no wonder there are issues.
Disappointing that this is still the case.

Do we need to submit a bug?

68

you have complete control over this - it might take some work to get it right.

PETG as support for PLA just worked.

The other way was quite a bit more fiddling. For me the solution was a custom PLA filament that uses all PETG temperatures. This seems to have fixed the clogging on filament change which I assume is the gcode you are talking about.

Since then using PETG and PLA as support interface has worked great.

69

Thanks for this info, it should be very helpful on my current project (and likely many to come).

70

I found flushing into infill caused poor infill bond, resulting in infill layers separating.
going to try upping flush volumes to see if issue resolves.

71

Lots of great stuff here. Thanks, guys.

I only see a couple of mentions about the individual filaments here. Specifically, I’m wondering about additives in the different brands/types of filament that may be causing problems like residue left in the nozzle causing adhesion problems with the next filament.

Here we’re talking about PETG and PLA as if all the brands, or even the batches being identical. This cannot be true. Some filament brands - PLA or PETG - do have different temperature requirements. There may even be batch to batch differences. And you may buy two rolls of filament next to each other on the shelf, manufactured by the same company, on the same day, and they’re two different batches, with slightly different chemistry. And we know a roll that’s been open for a while is different than a roll fresh out of the vacuum seal.

Our solution, when it’s critical, has to be calibrating every role of filament, and testing every combination of filaments.

72

I have the same issue. Tried with different PETG brands and a range of settings. I can’t get the PETG to a clean print leading to surface finish defects (at which point I might as well use regular supports and bridging settings) to even failed prints.

I can’t embed the photos it seems but the PETG interface layer ends up detaching or bunching up for example.

73

I have been having very similar issues - PETG support working for small areas, but larger interface layers have been suffering terribly from insufficient adherence to the PLA support structure, and subsequently pulling away - mostly during turns - and then ending up with lumps and blobs.

Managed to get some improvement with this:

  1. Increasing the nozzle temp for PETG way up to 275 (eSun filament)
  2. Slowing the interface layer down to only 40mm/s

Adding to the problem was the eSun PETG profile I downloaded (from eSun) for my X1C had an error in it for the cooling fan parameters - the max and min were reversed. This meant that the fan was running always at 40%. I have corrected this and lowered the speeds a little - my working theory is that higher temp and lower fan allows for a little more time for the PETG to be molten on the PLA support surface, perhaps allowing a better bond. Not sure how valid this is, but it has gotten me from total spaghetti failure on the interface layer to something that is vaguely workable (though far from perfect).

For some reason I also can’t share the images :frowning:

If anyone has had any better success with large interface layers in PETG - please share the secret sauce! :smiley:

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74

Also set the flushing volume as high as possible to get rid of impurities in the nozzle, if you print a cleaning tower, double it additionally for example and also double the volume at the cleaning tower (can be adjusted).

77

You did wonderful with your English and your instructions. THank you so much for taking the time

78

Did anyone open a buy on Bambu Studio trying to flush PETG at 220c?

I have done a total of 2 prints with opposing filament type as the interface.

The first time was months ago with a PLA print that had PETG as the interface, and my extruder clogged so badly I had to replace it because pulling it apart and putting it back together again didn’t fi it. Bambu Lab replaced it under warranty and told me it was because I didn’t leave the door open even though the top was vented. It never occurred to me that the temp being too low would be the cause because didn’t sit there and watch it during the filament type swap out. I just assumed it went to 250c like every other time I have seen it purge out old filament.

The next time was a week ago when I did a very small PETG print with PLA as the interface, where I made the other setting changes mentioned at the top of this post but not the GCODE modification.

I’m wondering if that is still an issue with the latest version of BS, and if so then we should probably open a bug report on it.

79

A little late to the party… but this “issue” is still present as of Aug 2024. In the “filament change” GCode, there’s a line that explicitly states (paraphrasing):

If previous filamet was PETG, set temp to 220, otherwise, set to max temp.

TBH, this makes ZERO sense to me, as the comment line right above that states “always use the max temp”. So… I just commented out that block and left the “set max temp” line.

Works like a peach!

80

so, I did a lot of testing, and in one case couldn’t get a successful result. My goal was to print PETG and use something else as support interface. I tried the Bambu PLA/PETG support material, and some PLA, but every time it switches from PETG to PLA/support material I get a clog. I tested the other way around, no problem. Any ideas why that is, and how to get it to work?

81

you mean this part?

; always use highest temperature to flush
M400
{if filament_type[next_extruder] == "PETG"}
M109 S260
{elsif filament_type[next_extruder] == "PVA"}
M109 S210
{else}
M109 S[nozzle_temperature_range_high]

to me that reads like “if next filament is PETG use 260°”

82

Yes that’s the section.

In my version of Orca slicer, the “if PETG” section set the temp to only 220

Easy fix, if you don’t mind editing gcode… But baffling why that’s there. But as I type this I realize I haven’t updated the slicer since before getting the Bambu P1S, so I may be running a really old version!

83

Check the max temps in the filament settings (both materials) is set to a single temp below the max temp of the lower temp filament and above the min temp of the higher temp filament. If possible, keep a safety margin of 5-10°.
Nothing fancy needed.

84

ok, I set the PETG to 230 max, and the PLA too… while it worked fine this time, PETG still was flushed at 260°. Now I’m testing the Bambu support filament for PLA/PETG. I set both filaments to 220° this time, since that’s what the Bambu site states as max temp for the filament, though it automatically was set to 240° before… maybe that was the reason it clogged before (too high temp). I’ll update if that stuff works now :wink:
Edit: aaaand, it clogged again… that stuff is just useless, I give it up and stick to PLA (with PETG)
Edit2: still have on occasional clog on filament change, but retry seems to solve it