M2 Nozzle Clog: FOD

This happened while switching from natural to black PETG:

M2 nozzle clog - exterior
M2 nozzle clog – exterior

A closer look:

M2 nozzle clog - exterior detail
M2 nozzle clog – exterior detail

Those pix happened after trying to extract whatever-it-is with tweezers, so it’s definitely something with a higher melting point than PETG.

Removing the (warm) nozzle with the block held in a vise reveals a tuft of something:

M2 nozzle clog - interior
M2 nozzle clog – interior

The tuft accumulated several turns while unthreading the nozzle from the hot end.

Heating the nozzle a bit more released the tuft:

M2 nozzle clog - extracted tuft
M2 nozzle clog – extracted tuft

The black-to-clear transition tailing off at the bottom came from the PETG around the tuft in the cone-shaped end of the nozzle above the aperture. The 100 mil squares suggest the tuft was a distinct entity, rather than a collection of threads, and might have been over 5 mm long.

Perhaps a fragment of PTFE or another high-melting-point plastic?

Reassemble in reverse order, reset the nozzle to Z=0 on the platform, and it’s all good.