How do you tell humidity vs dirty nozzle vs Z offset drift when adhesion randomly changes?

[TyreaXeno]

I swear my printer is messing with me. Same spool, same profile, same bed temp, and I’ll get a perfect first layer one night, then the next day the corners start lifting like I changed something. It’s annoying because it makes me feel like I can’t trust my “baseline” settings.

Last week I printed two small brackets back to back on different days and the second one started peeling at the edges even though I did not touch the leveling knobs. When you see day to day adhesion swings like that, what do you check first to narrow it down between humidity, a slightly gunked nozzle, or Z offset drifting? I’m trying to build a simple order of checks so I stop chasing ghosts.

 

[Chapman_Armor]

My order is always surface, nozzle, then Z offset. Clean the bed like it is brand new, then do a quick cold pull or nozzle wipe, then re check Z offset with a first layer test. Humidity usually shows up more as popping and rough extrusion, not just one corner lifting.

 

[Alan]

If it suddenly changes day to day, assume surface or Z offset before chasing filament