Under extrusion or some mechanical issue?
Greetings. I have a standard MK3s+, no mods, stock as in out of the box almost a year ago. In the horrible picture I took today you may or may not be able to see what I expect is under extrusion at the same layer height on every model I print. Printer is maintained every 100 hours or so and this just recently started. I have printed several different models and each fails at or near the exact same layer. All the calibration tests run with no errors, tried several different PLA and PETG spools, .15 through .2 layer heights; all the same. Is this a mechanical issue with the printer or a heat creep issue. I did change the nozzle about 3 weeks ago. Any ideas?
RE: Under extrusion or some mechanical issue?
I guess there is a limit to the time I can edit the original. I had to shrink the picture down. It's attached here.
RE: Under extrusion or some mechanical issue?
I really don't know what I'm looking at here... This looks like a lego block on fire...
But the usual response still holds: Best way to get good advice is to save the project from Prusaslicer's File menu as a .3mf file, zip it (or you won't be able to upload it), then attach it to a post here. This we can check the model AND your settings.
RE:
You sir are correct! Holy smokes that picture is terrible. I have attached some new pics. I did some cold pulls when I got home from work until the came out clean. So what's happening on each model is at around the 37mm height the filament gets all stringy. It still prints the part the ways it's supposed to be printed but there is a few mm of spongy filament and then it goes back to normal printing. I have a simple cylinder I added some negative space to printing now to see what happens after the cold pulls. Really strange, this machine has been running rock solid for almost a year. The only thing I have done is replaced the nozzle with another from the Prusa store.
RE: Under extrusion or some mechanical issue?
If that always happens at the same spot, I'm tempted to suspect some issue with the model rather than the printer or the filament. I've seen things similar to what you described happen when you have thin walls where the distance between inner and outer perimeter goes up a bit as the model is built in the z direction until the slicer adds some gap infill. That region then sometimes looks sort of spongy from the outside. Couple of ways to address it. Maybe turn off gap infill. Or use a height range modifier to increase the extrusion width in that area to remove the need for gap infill.