I’m printing using the filament that came with the printer and the default settings in SnapMaker Orca. Print quality is generally very good, but I’ve noticed that when I print relatively thin flat designs (around 5mm thick) the top surface blisters up slightly over the cells of the infill. This is very odd as if anything I would expect the surface to sag into the cells. It looks like the air in the cells is expanding and pushing the top surface up like inflating a balloon. It is quite subtle on the finished print, but observing the printing of the last few layers I can hear and see that the nozzle is scraping on the domed surface of the previous layer which cannot be good. I tried un-checking ‘Only one wall on top surfaces’ but that made it noticeably worse.
Any ideas, anyone? Maybe reducing the bed temperature after the first few layers (but I can’t find a setting for that)?
More top layers does help with the final appearance, but it also means there is more grinding of the nozzle against the domed surface of the previous layers. Over-extrusion is the best theory I’ve seen so far and I’ll try some experiments with that. I’ll also try a denser infill pattern, but that is not convincing to me since I’d expect the top layer to sag into the cells rather than inflating upward in the centre of each cell as seems to be happening.
My model is basically a rectangle extruded upward by 5mm and I am using the default slicer settings with no modifications, ‘0.08 Extra Fine @Snapmaker U1 (0.4 nozzle)’ profile.
This uses 9 top layers (0.72mm thick). I might recommend 12 top layers to get it closer to 1mm.
To me, 9 would be the bare minimum but could still show some texture from covering the infill up depending how good the overhang extrusion and cooling are. Those super thin infill overhangs aren’t easy.
Thanks Simon. The defect does look very much like this picture, but a bit less pronounced and more localised. However I’m still using the filament that came with the printer and it has been indoor at constant room temperature and humidity since the pack was unsealed less than a month ago. The bottom of the print (the first layer, touching the heated bed) could not be more perfect! Having come from a Snapmaker 2.0, one thing that seems different is that the heated bed is maintained at a high temperature throughout while the 2.0 lowers the temperature after the first few layers. I did wonder if the air trapped in the infill cells could be expanding after the cell is capped inflating the top surface upward?
If you’re using PLA, don’t fully seal the top cover—keep it half-open in winter and fully open in summer; otherwise the ambient temp can get too high and hurt PLA quality.
For the issue you described, use elimination: change just one variable and compare. For example, in a half-open enclosure, print the built-in 4-color dragon with official filament. If it looks good, the printer and toolheads are fine, and we can focus on your slicer settings or possible moisture in the filament. Let’s check the result together!
I’ve done some test prints using a 50x25x5mm box with 3mm filleted corners (please rotate the picture in your head, I cannot figure out how to do it in this editor!):
This is actually five separate runs (1 and 2 are displaced towards the rear of the original print position, 3,4 and 5 are at the position printed).
This was printed at the default position at the centre of the bed using the default settings. It duplicates the original problem with a simpler test piece.
I did a full flow rate and bed levelling calibration and reprinted - no improvement.
I noticed that only the right side of the test piece was pillowed, so I tried printing displaced to the left - perfect!
But then I tried displacing to the right of the centre line and it is still just the right side of the piece that is pillowed. I note that the layers are laid down starting front-right or rear-right and proceeding to the left, could this be important?
Final test piece all the way over to the right of the bed - perfect again!
Position on the bed seems to be important, but only the right side of the test piece (the first part of each layer printed) gets pillowed even if the left side is in the same position as the right side was when it was pillowed.
I think you need to do a mechanical bed-leveling first to make sure the physical platform tilt is minimal. Most auto-leveling systems then use software to compensate for the remaining small height differences on top of that. If after physical leveling and printing with auto-leveling checked it still looks like this, use these test photos and contact support to request a new heated bed.
I do not believe this can be mechanical levelling of the bed, although it could be that the bed itself is not flat enough. If mechanical levelling would help, surely the problem would be worse towards one edge or one corner of the bed, not towards the middle? Besides the first layers look fine in all cases.
Here is a new set of tests mostly around the periphery. Note that I used a different filament (also a different nozzle) to eliminate that factor:
This is actually nine separate runs which I have placed on the plate to show their approximate position when printed. The central one ‘MM’ as before is unacceptable while RM and FM have noticeable pillowing, but not so bad. The other six are perfect. It is hard to get the lighting right to show the extent fully, but MM, RM and FM all showed clear signs of grinding during printing.
I also did a test turning bed heating off immediately the first layer was printed, resulting in cooling to about 40C when the top layers were printed. There was no appreciable difference. I did try printing with the bed at room temperature throughout, but it broke away from the bed after a few layers. Once I got a good print in the centre of the bed by both reducing the bed temperature in this way AND slowing down both cooling fans to about quarter speed, but I was unable to repeat this with just one factor at a time.
During these tests I found a couple of bugs in the software:
As shown in the photo, the priming stroke for single-colour prints does not avoid the model footprint on the bed, resulting in a filament of unwanted plastic attached to the print.
Snapmaker Orca has settings for first layer and for subsequent layer bed temperature, but the first layer setting is used throughout and the subsequent layer setting is ignored. When doing the temperature test, I had to watch the print and manually reduce the bed temperature once the first layer had printed.
As suggested I will raise a support case and refer them to this thread.
Just to give closure on this, after a lot of tests support were eventually able to reproduce my problem. Turns out it is a problem with the Snapmaker Orca 0.08 Extra Fine @ Snapmaker U1 (0.4 nozzle) profile (the default profile). They changed: Sparse Infill Pattern to Gyroid and Internal Solid Infill Speed to 250 mm/s. This does seem to fix the problem. I am puzzled I seem to have been the first to notice this since I did not change anything in Orca, just sliced using the defaults.
