Mangled corners with overhang

[wmattias]

Hi!

Printing some pretty standard stuff, using PLA with fairly standard/conservative settings.
Most things print well, but I seem to keep having problems with corners that have overhangs. For some reason they get mangled if the corner degree is too high:
1. Any corner angle with no overhang works well
2. Straight overhangs work well
3. Corner angle of 45 degree and overhang of 45 degree works well.
4. However, Corner angle of 90 degree with overhang of 45 degrees gets mangled.

Posting some pictures below. It's probably some beginners mistake I'm making, just can't figure out what it could be.

Update: Added a 4th picture to give a better view of what is happening. Essentially, the outside of the 90 degree corners don’t stick to their layer height and instead curl upwards as the cool.

 

[Driftrotor]

how much part cooling at you running?
i had a similar issue and increasing my part cooling improved it.
seems counter intuitive but i tried lowering it first and also no part cooling but it just made it worse.
in the end i added another 10% part cooling and that seems to have done the trick.
another reason may be that it is slightly under extruding (like 0.5 - 1%) so the corner does not have enough material to bond with the lower layer and just curls up.
you might have to play with both settings to find the sweet spot.
hope this helps.

 

[NoGuru]

Agreed, this is part cooling or an issue with the MCU stalling on the corner but probably cooling.