Good results with what filament?
ASA and using PETG as a support interface.
Hi there, I am doing a print using PLA+ and PETG as a support, 2 top interface, I have noticed that during the 2 interfaces with the PETG the nozzle fan was stopped. Why ? Because in my PETG profile my setting is no fan for the first 3 layers, so 2 are not enough ?
Is ok or I need to create a petg profile for the support ?
This worked flawlessly. I went a little overboard on the purging and might tune that down some, but this definitely solves one of my biggest 3D printing gripes.
I just did the test (PETG in support for PLA), and it works incredibly well… Much better than Bambu’s W, with the W my parts were brittle at the supports, I think, thanks to this forum which I have just understood for what, it is certainly, because the level of purging of the W is not sufficient enough!
Hi
Very intersting thread! Recently I did a lot of printing with support involved. I use PLA-CF with PETG as interface layer, which works very well.
Well, the more you dig into the topic, the more flaws you will find.
I had some issues with Bambulab Studio, which I describe here:
This is pure software and should be solved soon by bambulab.
I never had trouble with clogging. However, I’m also concerend about the loss of structural strength. Often it will not be noticed, because the part is strong enough. But for sure there are some situations where you just need all the layer bonding strength possible.
Does anybody know the volumetric flow of the flusing? Maybe the flushing volume could be significantly reduced if flushing would be done at a much higher flow rate (higher than for printing with the same material)?
If even 999 mm3 will not be enough to get the regular layer bonding, this would be a real bummer!
I’m trying to understand what is happening whilst my X1C is flushing, changing from silk PLA to PETG (as the interface filament).
Silk PLA prints at 230C. When it’s time to change to PETG, it pulls the PLA back into the AMS, but then actually LOWERS the temp to 220C when it starts to push PETG through. After it’s pushed through PETG, it wipes, pushes more PETG through (still at 220C), then wipes again, only THEN raises the temp to 250C (as per the start gcode setting), pushes more PETG through again, before it finally prints the interface layer.
Then the same in revers when switching from PETG back to PLA. Lots of filament wasted it seems and worried that the I’ll get a PETG clog when it’s pushed through at 220C.
Anyone able to explain the multiple flushes at lower temps?
Thanks.
It uses the Min/Max temp settings from the filament definition. You should change those to ensure that throughout the change the temperature remains above the lowest melting temp of the two materials and that materials maximum temp. I always set both materials to the same min/max temps inbthese cases.
In the gcode it has a set temp for loading and unloading filament, from what I have seen it does not look at what filament is being loaded or unloaded.
Thanks but that’s not quite what seems to happen here.
Silk PLA max temp in filament settings is 240C, print temp is set to 230C
PETG max temp is 270C, print temp is set to 255C
What my printer does during the change from silk PLA to PETG or vice versa is:
- Flush @ 220C
- Flush @220C
- Flush @250C (which is set in the start gcode)
I haven’t made any gcode or profile setting changes and do not understand
a) why is it flushing 3 times? (@silver118822, is this the unload, load, flush sequence? But it seems to be pushing filament through at each occasion.)
b) why flushing at 220C (which is neither the flush, the print or the filament max temperature)
You are entirely correct.
My apologies for the likely outdated lessons learned I picked up during PLA, PETG, BVOH trials using Generic material settings between late September, Mid-November.
I can indeed confirm that my current print using Bambu PLA Metallic and Bambu PETG Basic and sliced with Orca 1.9 has exactly the same settings and behaves exactly the same as yours.
Looking at the gcode, I remember that back in 23 I was able to resolve my heat creep issues when I spotted the temperature settings being set as variables in the manner I originally described. However, I was using Generic material settings at the time which needs to allow more flexibility than a single brand.
While I did spot the pulsing flushing implemented in the gcode generated by the slicer (implemented to avoid poop chute issues with high flush volumes: no extra waste but you may want to look at the volumes you set), I was actually not able to correlate the gcode settings (in particular M620) to what I am seeing with my printer (temps in gcode are higher, so maybe I am looking at it wrong).
Maybe somebody with better gcode and Studio/Orca experience than me is able to provide a better explanation?
I’m currently using up the sample spool of Bambu’s Support for PLA that came with the printer. It works well but my plan when I’m out of it is to try PETG.
I have a specific question though. I’ve skimmed through this thread but didn’t see the answer:
While I understand that bridging PLA over a support interface of PETG should work wonders even with 0% layer adhesion, my concern would be when it’s not a bridge, but something that would print entirely in the air without supports. Like Gandalf’s left hand in the photo. If it doesn’t adhere at all to the interface layer, I expect it would not yield a very good result. Can anyone confirm that too will work fine with PETG?
I had a similar case last year where I wanted to print a PETG “island” on BVOH. It led to the nozzle happily pushing the “island” around on its bed.
In the end, I used Primitives to build two dedicated, solid supports with hard interfaces to stabilize the “island” while the support material was used for droop prevention with manual tree support, BVOH support, 0.0mm separation.
That allowed me get a good print despite the support interface material not adhering to the model…
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Does anyone know a reason why the PETG interface layers might be curling up and sticking terribly to the PLA supports?
I’ve been thinking it might be simply due to PETG and PLA being so “unsticky” to each other that the printer simply can’t lay down the PETG first layer of the interface properly on top of the PLA supports, but many people here and elsewhere have had success, so I’m wondering if it’s something I’m doing wrong?
The settings I’m using are:
Support interface speed: 10mm/s (have tried from 10 to the default of 80mm/s)
Top and Bottom Z distance: 0mm
Base pattern spacing: 1mm (have tried from 1 to the default of 2.5mm)
Top interface layers: 3 (have also tried the default of 2)
Interface pattern: Rectilinear (have also tried the default of concentric)
Top and bottom interface spacing: 0mm
Support/object xy distance: 0.5mm (have also tried the default of 0.35mm)
Purging volumes: 800mm3 both ways between PETG and PLA (although I think in this case this isn’t a factor for the interface layers not sticking to the PLA and curling up, because if there were any residual PLA left in the nozzle, then it would make the interface to support adhesion better not worse)
I’m using snug supports in this case, but I’ve had issues with other support types as well.
I’m printing with a Bambu Lab A1 using Bambu PLA Basic White and Bambu PETG Basic Black, which has been dried for 8 hours at 55C in a filament dryer before printing.
Temperatures are the default of 220C for PLA and 255C for PETG.
Here’s some pictures of what I mean by the terrible interface layer quality:
2nd interface layer:
3rd interface layer:
1st layer of the main print on top of the 3rd interface layer:
1st interface layer:
2nd interface layer:
As you can see, there are a ton of PETG blobs and spikes sticking up from the interface, which will inevitable get printed on by the main white PLA, which means lots of bits of PETG get trapped inside the main PLA print which will weaken it. Also because of this, the surface finish is not great on the overhangs printed on top of the interface layers, and the supports do not come off fully cleanly, with little fragments of PETG left behind that need picking off individually with pliers, and even then there are some trapped bits of PETG that are impossible to remove.
Also, this level of quality is only because I slowed down to 10mm/s and added a 3rd interface layer. Using the defaults, the results are even worse, and sometimes result in complete print failure from the PLA not being able to be laid down properly on the PETG interface due to the blobs, and the nozzle then catching the curled up PLA and PETG mess.
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Hi there, I made a quick test design with my settings. Hope it helps!
Thanks to Jim-Knopf for the settings 
(Support Filament Testmodel - any PETG as support for PLA and more by PrintMich - MakerWorld)
Do you just put this code at the beginning of the ‘Machine gcode’ block? LIke so?
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!
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.
It should be an upgrade to their printers!
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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 
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?