My slicer says same profile but top surface looks like trash

[RosaBW]

So I thought I had everything dialed in. I went from test prints to usable parts with smooth tops. That was until yesterday I just sliced a simple box, nothing fancy, and the top layers are coming out bumpy and ugly. No weird filament, no mis-calibration, same nozzle, same bed surface.

From what I found online, some people say cooling fan behavior and infill strength can mess up how the top fills, especially on bigger flat surfaces. I’m thinking maybe layer height or top layer count or flow settings might be the culprit this time.

Before I throw out all my settings, I want to see if anyone else had this happen out of the blue. Did any small tweak or re-slice trigger a top layer meltdown for you? I’d love to compare notes or maybe get a “yes that fixed it for me” kind of answer.

 

[BlueOak]

that’s usually top layer + infill mismatch. If your slicer kept the same profile but you changed model size or infill %, the top layers can sag a bit and look like trash even with good settings. I’d try bumping the top layer count up by 1–2 and slow the top speed a bit. Happens to me whenever I print a big flat lid after a week of tiny parts.

 

[Alan]

Good call on not wiping your profile right away. Flat boxes tend to reveal things that don’t show up on test prints, even when everything feels “dialed in.”

Was this part taller or built differently underneath compared to what you printed before? Curious if others here saw this pop up just from changing the model.