To achieve faster speed printing for functional and draft prints, I wanted to try a 1.0mm nozzle with my Neptune 3 Plus. This is the first time I replace a nozzle so I followed YouTube videos and replaced the nozzle. After replacing the nozzle I leveled the bed with manual + automatic leveling. The extruder seemed to be working, taking and extruding the pla filament. Success? Sure not yet .
I started fiddling with cura profiles, increased line width, layer height, temperatures for head and bed, decreased speed.. Tried a few times to achieve adhesion and printing. So things looked good. After the trial and errors I was satisfied that I could print now.
I started a 1 and a half hour print. It started well and I went for some tv and started checking the video feed. Things started well, but in time some warping occurred. It was evident that the print would fail. However I wanted to see how things will end up so let it continue. Sure it ended with some spaghetti.
Everything is as expected up until now. So I returned back to stop the spaghetti. But there was a strange blob at the end of the extruded filament spagetti. And the nozzle was there?!? I am still confused how the nozzle ended up out of the extruder being intact.
OP could compare a thread gauge to the female/internal threads on the block to find out. Or, more simply, do two things.
Throw a brand new nozzle in the block, grab it with pliers and apply strong, but not hulk, downward pressure (perpendicular to block) on the nozzle and see if it pops out. Don't get too strong here because you'd just fuck things up if they aren't already... you're just trying to mimic filament pressure
Melt the filament off the ejected nozzle, clean it up (brass wire brush, perhaps) and do the same test as number 1
If #1 pulls out a new nozzle... Yeah... replace or rethread (good luck) the block.
If #1 sticks strong but #2 pulls out, replace the nozzle and hope it was just a shitty, undersized, nozzle. I don't expect this to be the case, but eliminate all simple problems before trying to remedy a (maybe non-existent) larger problem. Troubleshooting 101
After this I used a 0.8 nozzle. And could print with it. So threads are still there.
I suppose I mistakenly didn't fully screwed the 1.0 nozzle. With the large layer width Pla stuck on the nozzle, as the print was a rectangular shape on each turn that pla applied some tork and nozzle unscrewed.