Thank you so much for this! I have saved your very well-written instructions in my Bambu Help and Tutorials folder on my computer. I have some projects that need supports and look forward to following your instructions when I print them once I receive my order of Support Filament from Bambu Lab. 
this is 100% accurate with my testing as well. Have you found any resolution to this? I even tried to increase the prime tower to 100x100, makes no difference. The only thing else you can do is add another model next to your main model and flush the purge into that “temp” model’s infill; That’s cumbersome.
Set flushing volume to 3x
I tried this and still get separation at the layers there is a switch from PETG to PLA (PLA as support). 
I kept the tower and changed flushing volumes to 800 on both of the 2 filaments changes in my print. The results were perfect. I’m printing with PETG and using PLA as support. PETG prints on the bed and the PLA layer is only the support interface. I think it only printed 2 layers as support interface. The PETG support on the bed peeled off - it actually stayed on the bed. The support interface didn’t fall away, but peeled off perfectly. Thank you for detailing the parameters and for your suggestions… they work great.
My problem is that sometimes some places don’t count as support interface, and they make spots that didn’t generate as PETG hard to remove.
Thank you! This sounds just like what I’m looking for, but where would I find the option to, Set the flush volume from/to pla/petg to 800?
Thank you for this info, but I don’t have that flush option in my slicer.
It only shows when you have 2 or more filaments loaded.
Hi everyone, I’m trying to use PETG at the interface of the support for PLA prints on my X1C. The print of the support comes out perfect, however there is an issue.
Where the print includes both PLA and PETG, i.e. where the printer is changing the filament, the thickness of the part changes. You can see in the attached photo a “ring” corresponding to the layers of the interface. When I tried to print this part the first time I made a mistake and the whole support was made out of PETG, and that entire height of the part was slightly thicker and somewhat shifted to one side —perfect by itself, with no irregularieties, I just noticed when I had the full part in my hand. So it’s not some random misalignment, it’s really consistent and it seems to be limited to the inner side of the part. I thought it was something due to going back and forth to change the filament, but it’s not something that I have ever observed when printing with different colours. The only difference is that here I’m not using the purge tower.
Does anyone have experienced something similar? Any suggestion?
Im very new to this, sadly I cant upload an image, can someone show me the up to date settings, as under the support tab, I see many more not included in the original. TIA 
I left my support as tree (automatic) and just changed the material settings and flush settings between the two to 300. Printing PETG with PLA as the raft interface and the part pulled right off the bed and separated cleanly with the supports still stuck on the bed
Old Thread, but I wanted to add some materials.
ABS is excellent support for both PPS-CF(Polymaker) and PPA-CF(Siraya Tech). I am using the H2D with PPA-CF in the left nozzle and ABS in the AMS on the right.
I used a lot of these same settings, except I changed the support angle to 90º and extended the base 2mm to make it easier to remove. I had a very tight thickness tolerance on my last set of parts, I was able to hold it within 25µm which I found very impressive, especially on supported overhangs.
Why does my PVA keep breaking? Even right out of the packaging it did it. Every time I have to take off the buffer and disconnect the tube to find the broken piece.
You really do need to dry the hell out of it. Especially when new.
I myself switched to BVOH a long time ago as it handles better. Still needs to be dried well and repeatedly as it literally keeps the dessiccant dry 
But most of the time PETG for PLA and vice versa does a good enough job.
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