I’m printing a small cover in PETG, but the supports are fusing to the print. What settings are recommended? I’ve tried PLA as an interface material, but this also fused to the print.
For the print with PLA interface I changed the following settings from default:
Type - normal(auto)
Style - Snug
Support/raft base - PETG
Support/rafe interface PLA
Initial layer expansion - 0mm
Top Z distance - 0mm
Bottom Z distance - 0mm
Base pattern - rectilinear
Top interface layers - 2
Bottom interface layers - 2
Interface pattern - Rectilinear
Top interface spacing - 0mm
Support/object xy distance - 0.5mm
For the fully PETG print, I reset to defaults and changed the Z distance to 0.275mm
It looks like you’re tweaking your supports well outside the defaults. If I had to guess, you’re over-tweaking based on the number of changes you’ve made. That’s an easy trap to fall into. However, without an image of the model, it would only be guesswork to offer meaningful suggestions. Please upload a screengrab of the preview and the slice.
In the meantime, it appears that you have set the Z distance to zero, which will definitely ensure that your supports will not separate easily. They will need to be cut if there’s no interface gap. Unless there is a reason for having the supports bond directly to the model, the default should remain at 0.2mm. In rare cases where there is a stubborn support, I have used modifiers to even increase this beyond the 0.2mm but never zero.
This support interface material pictured here is what I mean. It needs to be there, and if you set the interface to zero, you’ll get a direct bond that will require cutting the material away. There are times when this is desirable, but most of the time it is not. Again, if we had an image of your model, it would be easier to tell (hint ). More importantly, we need a model sliced and shown so the transition boundary is visible.
It’s unclear why you’re using the snug pattern without fully understanding the support you’re trying to achieve, which is why we need a screengrab of the model. The defaults work for most shapes. The same is true for the interface pattern. Sometimes changing it from the default is necessary, but often just adjusting the model’s orientation will do more. Again, this question would have been answered if we had an image of the model (hint ).
Of the defaults, the only thing I can recommend changing is the XY distance. The 0.35mm default doesn’t work well on most models with walls that aren’t perfectly vertical with the print bed. I have permanently changed the Bambu defaults in my printer definition to 1.35mm for this reason. You can even go as high as 2.35mm. This will create a healthy gap, allowing for easier separation of the support and space for a small tool or blade to be wiggled underneath.
I use the PETG interface a lot for PLA prints to very good effect. The other way round is a bit more challenging as this requires printing of a hot melting model material on a lower melting temp interface material.
What you could try:
Use a concentric interface for less intermaterial “grip” and a smoother surface
Revert the Bottom Z distance to its default
Use Adaptive Layer height and fine tune for very fine PETG layers at the interfaces. Halfing that layer height reduces the heat input by a factor of 8, greatly reducing heat input into the PLA
But be prepared that a PLA interface for a PETG print is more challenging than the other way round.
). More importantly, we need a model sliced and shown so the transition boundary is visible.
