I have the same issue on almost every print so far. The top layer has these spots (see pictures). The problem seems to come from the infill, during its printing the are blobs of filament sticking up and the top layer cant get smooth after that.
As said above, every print is affected, some more, some less. I could not find any other topic with the same issue here or anywhere else, so I would highly appreciate any input on how to fix this.
Below are some pictures of different prints with the same top layer issues:
see if you can reproduce the problem on a small print, like a calibration cube type of print. this way you can iterate quickly to try different settings
However, I am wondering why no one else seems to have these issues. The printer is all new with all standard settings and Bambu Labs own basic filament. I just think that this should work without a lot of calibration required. Ultimately, this was the reason why I chose a bambu lab printer over a more basic 3d printer. Any chance this could be a bad nozzle?
Ya this is not normal, is the green pla doing the same thing ?
Is pla the only filament you have run in the hot end ?
What layer height are you at and what speed mode are you running like standard ?
Also just so you know the stl files on the Bambu lab are not that great of settings so download them and slice them yourself Links to Bambu Lab STL models
Next step clean the Micro Lidar and let’s see if you get better results ?
If not, turn the flow calibration off before you print and set the flow ratio to 1.05 just so we can test and see what happens this flow ratio should be in the ballpark.
I got a similar issue. With a lot of painstaking tests, I found out why it happens only on the top layers whereas all the other layers look good. My hypothesis was that if all my other layers look good, how could it be that only the top layer(s) start messing up?
I deduced that it must be related to some difference in settings from the top layers vs the bottom layers. I realized that in the default settings:
(1) The bottom-most layer has NO cooling. There’s no side-fan (AUX fan) or part cooling (from extruder). The bottom-most layer has 50mm/s speed (very slow).
(2) The middle layers (infill and wall layers) have the side-fan set to 70% and part cooling set to 100% and speeds between 250-300mm/s.
(3) The top surface also has the side-fan set to 70% and part cooling at 100% BUT the speed is set to 200 mm/s.
After some tweaking, I deduced that this top-layer problem must be related to COOLING and SPEED differences on the different layers.
I decided to turn the side fan to 0. This side fan is mostly unnecessary for PLA (there are some cases where it might be helpful, but largely no).
This helped a bit but I still had some top layer issues.
I then decided to bump the top surface speed to the same as my internal/sparse infill speed (270 mm/s). This completely fixed my other issues being the top surface was going a bit too slow causing the part cooling to cause waves in the plastic.
TLDR
If using Bambu filament, ensure you are selecting Bambu filament profile. Otherwise, use Generic PLA.
Try eliminating cooling and see if it helps.
Try bumping up the top surface speed to match the infill speeds.
I’m here reading this thread because I’m not thrilled with my top layers. I was wondering if I should slow the top layer speed way down to something like 50, but you’re saying you went the other way and made it faster!
One simple point is - often this helps - use gyroid , amd and bit bigger percentage of the infill. Dont use grid, this causes an lot problems. 3d printing is all about making your Experiences . Over time you will get less errors.
