Is dust (rust?) in nozzle thread normal?
I'd been getting a lot of clogs lately and I was consistently getting black rings on my cold pulls right around where the nozzle meets the heat break, so I decided to remove the nozzle for thorough cleaning and when I did, brown dust fell out.
The entire length of the nozzle's thread was covered in a fine, brown dust very much reminiscent of iron rust (but there's no iron here, only aluminum and brass, right?). When I saw that, I decided to disassemble the whole hotend to check for more issues, but everything else was clean (even the heatbreak portion of the thread in the heaterblock).
Is this normal? I've never heard of anything like this, nor have I seen it in any maintenance tutorials or videos.
I've head the printer for 3 years and have done ~1000 hours and ~1700 meters of filament and this was the first time I removed the nozzle.