Pillowing on very top surface
Hi, I just can't figure this out. I had e pillowing that all of a sudden has started.
I printed a smaller similar piece with the same setting and it's perfect.
It seems to be on the top layer only. The other layers are immaculate.
The layer on top of the infill looks great.
Infill looks great.
Cf Petg. 4 too layers, 0.2 mm layer height.
I tried turning on he part fan to 45% as it was off before.
12 Replies
Is that ironing or something? Not sure what that is
You can increase the density of the infill towards the ceiling, allowing you to print with sparse infill and still get great surfaces.
What slicer are you using? Check last layer before top starts. In Orca and Bambu slicer there's bug, which causes bridge to happen on top of infill
From another Discord
I finally found the reason why my high density infill parts had really rough, over-extruded looking top surfaces. Bambu Studio bridges over the infill on the layer before the top layers, and that bridging uses the regular bridging settings, which uses a very high flow. This is usually fine for low infill density parts as it can flow into the gaps between the infill lines and it will help build a foundation for the top layers. But, because I'm using a high density infill, the bridging flow is wayyyyy to much and there's nowhere for it to go but up and sideways. The infill bridging ends up having like a 0.4mm layer height worth of flow
With the bridge
Without the bridge
Both slicers have setting to turn down the internal bridge flow. It doesn't seem to be working in Orca tho
So this might not fix an underlying issue. But I fix this by increasing the layer height to 0.28 mm.
On a 0.5 nozzle and CF PETG 0.2mm seems to come out like this on my printer.
No ironing was done. The fact there is over extrusion clearly at the gaps on infill might indicate too much flow at the bridging layer as you suggest @McSneaky. But I'm not sure why it's only so pronounced at the top layer.
Try lowering fan speed on internal bridges...
Try making a test with 7 top layers and see if the problem still exists.
FYI I had exactly the same issue with prusament petg CF on a Prusa XL. I got one roll to try out, and it's made terrible prints every time. And yes, I dried it for hours before first use. It's like the profile for this stuff is wrong, or a bad batch maybe. I was using Prusa official profile for this material on the XL. Pinging prusa support about it is on my to-do list.
Change top shell thickness to 1.2mm, make sure you have optiimized the fan logic for this filament specifically. 30% typically and no more. Do bridging tests to get the right combo of temp and fan speed. Make sure the toolhead is slowing down before bridges to like 15-20mm/s. You need those top bridging layers that cover the infill to stretch across, not sag. No fan on top layer and slow it down so the nozzle can "mow" over any wisps.
also increase z offset like 0.03 for petg only in your printer profile.
and use gyroid infill instead
One on the left is 2nd stage. One on the right is 3rd stage of my tuning. A 4th is on its way. The first try had the pimples all over it like you showed. I've dealt with this before on my Bambu and VCore 3. I've printed a thousand parts in this material by now, the above should work for you.
