What do you see on the part?

Before you touch the slicer

1. The printerIf it printed fine yesterday and not today, it's almost never the profile. Check the plate, the nozzle and the room: printing at 15 °C is not the same as at 30 °C.
2. The plateWash it with water and dish soap, and don't touch it with your fingers. Skin oil is enough to make a part stop sticking.
3. The filamentA spool that has soaked up moisture gives strings, bubbles and brittle parts. Dry it before changing settings, and pick that filament's profile in the program.
4. The slicerOnly now. And before you print, step through the preview: that's where you spot missing supports and odd areas.

Change one thing, print a small test and compare. If you change three at once and it gets fixed, you won't know which one did it.

Bambu Studio has tests in the Calibration menu: Temperature, Flow rate, Pressure advance and Retraction test, plus some more advanced ones. With a Bambu Lab printer, that menu only shows up with Preferences › “Develop mode” turned on. Each prints a test piece and you pick the area that came out best. Run them when you switch filament brand or type: several problems on this page go away with that alone. How to run and read each test →