Bowden / j head
Maybe try reslicing and using a different card to print from.
Difficult to diagnose whats happening without more info.
Does the print stop there, or some axis are skipping steps so alignment is off ?
The melted filament on the top does not look like something it printed, i.e not layed down following any gcode, just looks like random melted filament, infill pattern are off.
Maybe its the Z leadscrew and something is happening just at that height…try clean it and regrease it, and run the bed up and down the whole
hight and listen and look if something looks off ?
Did you stop the print there, or you came back and it was like this on the picture ?
Do you print from SD card, or printing over USB ?
catohagen said everything I was thinking.
Either the z is jamming at that point or something in the slice itself is corrupt.
Also the infill on that looks low. I thought those were supposed to be printed at 55% for strength.
Looks like a Z axis issue, The Z axis didn’t move up and the printhead crashed into the previous layers.
As some others guys suggested here above, try to grease your axis and check that the coupler is well tightened.
I had the same problem last weekend.
Thanks guys. Was a slicer problem. It was skipping a couple layers at that spot. The infill is a bit low. I’m printing at 45% with
2.0mm edges to compensate for it. 55% was causing issues with balls of melted filament between the layers.
Maybe you are printing too hot ? try lowering the temperature, PLA can print as cool as 190°C (varies from printer to printer tho)
If you try to print some smaller pieces or 20x20x20 mm calibration cubes first, and try one with say 230°C then a new one with 225°C
and continue this until the print fails with underextrusion. Then you know the last temp that worked and all should be better.
Balls of melted filament sounds like too hot temp and nozzle is oozing filament. I can also be cooling fan thats not cooling the layers enough.
Your corners looks bulgy too, like the acceleration settings are off. If the hotend or nozzle slows down too slow in the corners, the PLA will ooze out more than it should (more if temp is already too high). Stuff like this will throw off the dimensional accuracy of your prints.