I’m doing a large print, and about 1/4 of the way through, I started hearing this horrible, intermittent noise. Sounds very close to nails on a chalkboard. Naturally I assume something is starting to wear out (belt, roller, motor, etc) or there’s some parts rubbing together that shouldn’t.

The print seems to be going along fine, though, so I let it be until I couldn’t stand it anymore.

Finally sat down and watched it, and the culprit is the extruder fan blowing into the large, hollow tree support bases which was acting like a whistle. lol.

I’ve only been 3D printing for a little over a year, and this is the largest print I’ve ever done so far, so if this is normal, it caught me totally off guard.