The photos below show my result using PETG as a support interface layer with PLA, for comparison.
- Printer: X1 C with AMS (Firmware V01.07.03.00)
- AMS: V00.00.06.40
- Nozzle: Bambu Lab X1 Carbon 0.4 nozzle
- Plate type: Textured PEI Plate
- Filament: Orange Bambu Tough PLA and grey Bambu PETG Basic with standard Bambu presets as synced from the AMS (no speed, temperature or other changes whatsoever).
- Process: 0.20mm Standard @BBL X1C
- Process custom settings: Support tab only: support enabled, PETG selected for Support/raft interface, I forgot to reduce the Top interface spacing to 0.1mm as suggested above (see note below).
- Slicer: Bambu Studio V1.8.4.51
- Flow Dynamics calibration NOT selected when printing. This would only do Automated “Flow Dynamics Calibration” for the PLA, not the PETG. The “Factor K” is used for the whole print, and during every filament switch the printer will use the default “Factor K” for the PETG (I understand unless it is a BL PETG in which case the appropriate preset will be used based on the RFID identification of the filament - bit of a grey area as the documentation is ambiguous and I’m still trying to figure it out by looking at the source code)
Nonetheless, these are the only settings changed from standard:
The support block separated cleanly with almost no effort.
If Top interface spacing was reduced, the gaps between the grey lines would be narrower. A 0mm setting would make a solid grey interface layer, which only marginally improves the first part layer above the support interface layer.
The camera flash accentuates the surface roughness, but there are certainly not the imperfections that you are experiencing.
The first layer above the PETG support interface layer is not perfectly smooth, but it is more than satisfactory and illustrates what is possible using standard settings in Bambu Studio.
The Support/object xy distance could also be reduced to 0.1mm, particularly on small supported regions, and I’ve found that separation is still just as easy.
Bambu Studio and Orca could both do with settings specifically to improve the quality of the first part layer above dissimilar support interface material.
So to your problem…
- I suspect that this is a filament issue, not a printer (even though you have an A1) or slicer one.
- Try inserting a PAUSE at the first layer above the support, then take a photo when it stops printing of what the top layer of the support interface material looks like.
- Try inserting another PAUSE at the layer above that and take another photo when it stops printing, to determine when the defect is first evident.
- Using different colours may illustrate better if any PETG is left adhered to the underside of the first part layer.
- Using different filament spools, preferably BL, may have better results. Not because BL filament is any better than others, but because the calibrated presets would be used, negating the need for calibration.