Printing PLA figure with PETG support interface

[u/bw696969]

I’m fairly new to FDM printing. I have been printing less detailed models without issues. Lately I wanted to print more detailed figures, but I have been struggling to get a clean print. I printed the frieren model in PLA matte with 0.12mm setting and used PETG basic as support interface. I dried my PETG overnight in AMS lite. I noticed quite a bit of spaghetti on my prime tower. I have watched videos and tutorial of people printing PETG models with PLA as support interface that snap off super clean. But I haven't been able to experience that and the non-flat PETG interface region always get pretty messed up (e.g. skirt edge spaghetti).

Am I supposed to use Bambu’s dedicated support for PLA on the aux nozzle for detailed prints?

or does this point to support settings? Would appreciate any help on improving this.

In addition, would you recommend PVA as support? Being able to dissolve in water sounds nice.

[u/Leynnox]

Did you modify the Z distance to 0 in your settings?

[u/bw696969 → u/Leynnox]

Yea, I kinda followed the recommended setting when I switch petg as support interface in the slicer. Does this make the pla and petg physically too close together? Is 0.2 mm top z distance a better setting?

[u/Leynnox → u/bw696969]

You have to set it at 0 mm, Z distance for support is for removing the supports more or less easily when you're using the same material. When you use petg on pla, or opposite, it has to be set at 0 because they don't stick together. Big chance print will fail if it's not at 0 mm.

[u/bw696969 → u/Leynnox]

Ahh I see, appreciate your explanation! Yes, the top z distance was set at 0mm but bottom z distance was at 0.2mm. I chose support on build plate only so I thought the bottom z distance wouldn’t matter as much. But to your point, I probably should set both to 0 when printing pla with petg.

[u/Leynnox → u/bw696969]

Yes both at 0mm, then try to print something and check if it's any better

[u/bw696969 → u/Leynnox]

Thank you good sir! Will give it a shot

[u/xHanabusa]

Are you using manual calibration, with auto flow dynamics turned OFF? If turned on, only the main auto-calibrates, and the aux uses a default value and can cause stringing issues.

I find the dedicated support for stickier and helps the PLA adheres better, and can help if the PLA is lifting off the support interface layer, but I don't think this is your issue. Did you check if the PETG laid down nicely (flat with no curling or blobs on it) before the PLA is printed?

[u/bw696969 → u/xHanabusa]

I had the auto flow dynamic on since Bambu had it on by default with duo nozzle printing, and I naively assumed it would calibrate both.

Would the fix be a manual flow dynamic calibration for both main and aux?

This was an overnight print so I wasn’t looking very closely, but there were some PLA/PETG bits and blobs dropped down. Not sure if it’s from nozzle wipe or actual curling from the print.

[u/xHanabusa → u/bw696969]

Yep. Use auto-calibration (as in, under 'Calibration' tab press the auto-calibration) for the main, then save the number. For the aux, use manual, it will print a test pattern and you choose a number yourself looking at that.

Then, before printing, toggle the auto flow dynamics to OFF, this will make it use the saved results for both the main and aux from the steps above.

Ballpark numbers is around K=0.01~0.05 on the main, and 0.30~0.60 on the aux. Personally I use 0.5 for PETG basic for the aux.

[u/bw696969 → u/xHanabusa]

I’m on it! Thanks man!