Layer adhesion and cooling
I've had a MK3 for about a year now and have made some really nice prints. No real issues to speak of.
Recently, I flashed the 3.7 update and i'm seeing catastrophic layer adhesion after the first. Effectively the first layer goes down nice and smooth, sticks well, bonds and is flexible if I peel it away. As soon as the second layer starts, it barely sticks, doesn't even bond horizontally and can fray up and away from the print causing all kinds of clogs and mess. It is smooth, uniform and level.
I did a factory reset, re-flashed, changed the nozzle (0.4) and re-calibrated.
Again, same results. first layer is nice. The rest is almost like putting down fine filament. Loading the filament produces a nice even flow below the nozzle, straight down; no clogs, no thinning. The third also doesn't stick to the second.
I did find that removing the cooling fan deflector and increasing the PLA temp from 210 to 220 corrected the problem. I've kept repeating the batman test that came with the kit. Even different colors of PLA. I peel away the print before finishing the third layer. Overall Bonding is good. If anything my Z axis tends to run tight as I print many fine small fantasy figures and it seems to really help detail.
So a few questions;
What would change ? Same PLA roll (even tried 2 others) Hatchbox black like I've been running for a year now. Also tried silver and green.
Assuming there is a thermostat, can it go bad? Is it too cold? I've never run PLA so high before. If I run translucent PLA through it repeating "load Filament", sections of the free line are not clear and sort of cracked looking. Other sections are clear. Increasing the temp gives a consistent clear line.
If I run without the nozzle fan, what will happen long term? I assume it's there for a reason.
I'd appreciate any other advice.
RE: Layer adhesion and cooling
Have you done the PID calibration? It almost sounds like you're getting bad readings on the nozzle temp... except that 1st layer sounds like it's good.
If it's not a bad reading, then it sounds like... somehow... you're getting amazingly good cooling. There's nothing in the firmware that should have affected this, but since removing the fan (drastic) and raising temps helps, it would be worth simply turning down the part cooling fan when printing. Presumably you're using PLA. For PLA, the part fan usually runs at 100%. In PrusaSlicer, try just going into Filament Settings->Cooling and adjusting the speeds under Fan settings perhaps to 50% to see if this improves things.
It's usually a challenge to get good part cooling, so I'm really curious to see what the situation is. Is it possible the fan has been mounted crooked? Since you removed it and presumably remounted it, this is unlikely.
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