Hello, I have a problem with printing large surfaces. The middle area looks fine, but when it gets to the edges, the surface becomes strange and doesn’t seem to adhere properly.
I read in the forum that reducing the speed might help, so I already tried lowering it from 200 to 150, but that didn’t solve the issue either. I’m printing with PLA from SUNLU at a nozzle temperature of 220°C, an infill of 25%, and a bed temperature of 50°C.
Maybe someone can help me. Thanks in advance! 
If that is close to max bed size the problem might be uneven hating of the bed, should not result in such bad looks though.
Before wasting lots of filament trying to print this big part why not try a proper filament calibration first?
If that gives you the same k-factor and flow ratio as before (or close to it) it might be an issue of the sparse infill not being covered by a bridging layer properly or the sparse infill not being clean and smooth.
With the calibration done that often means all you need to change is the acceleration values down a bit.
Another tweaking option is the smooth discontinuity thing.
It basically adjusts the speed for certain moves so that the flow rate won’t change too suddenly.
The standard value here is (Ithink 155) - try something in the area of 120.
I never do filament calibrations as I find them to be a waste of time. A rabbit hole not worth falling into. The SUNLU PLA profile on Bambu Studio works just fine. SUNLU PLA also prints just fine using the generic PLA profile and the PolyLite PLA profile.
The patterns on your print look as if the auxiliary fan may be the culprit. I print a lot of large footprint prints and used to get prints that looked like that. Upon being advised to do so, I began turning the auxiliary fan off in the filament profiles and keeping the door closed, (I have half inch risers under the top panel) and the bad prints have all but gone away.
Ever so often I will get a print that just doesn’t want to lay down on one edge or another. Often times, rotating it by 90 degrees or sometimes 180 degrees solves the problem. If all else fails, you can always try brims as brims tend to hold prints down better than anything else.
What does the bottom look like?
The bottom is perfect. The print dont go up or something like that in any corner its just the top part. I will try tomorrow a new roll Sunlu Filament and first Calibrate it. But i think i calibrate it some month ago. Its just when i print something real big. Smaler prints are also perfect.
I too don’t run calibrations and print Overture almost exclusively. To solve the aux fan issue, I run a piece of painters tape across the outlet of the fan, bending it down so that it blows under the build plate for awhile. I’m not smart enough to turn it off every print and too lazy to fix the G code, the tape works every time.
I’m also a fan of using brim or brim ears (the second to last icon on the right). I crank brim ears up to 12 for no particular reason.
I thought brims only help to keep the print from detaching from the build plate. I don’t have that problem – the print adheres perfectly to the bed, it’s just the top layer that has issues. The plate is also too full to add a brim.
Tomorrow morning, I’ll load a new roll of filament, calibrate it, and then change the type of infill as well as the surface printing method in the hope that it makes a difference.
