Our 3D printers can't do small threads (<M10). Therefore, it is better to make a "pocket" (in FreeCad) instead of a "hole" using a smaller than the nominal diamater: D_internal
with
A M3 screw has a of 0.5mm and a of 3mm
https://en.wikipedia.org/wiki/ISO_metric_screw_thread
Modify the baudrate to 115200 in Marlin config file and build/upload new code.
Then you can use minicom (disable Flow control) for communication with the printer.
Use command M303 for calling pid autotune
https://marlinfw.org/docs/gcode/M303.html
For hotend:
M303 E0 C8 S210
for bed:
M303 E-1 C8 S60
http://bukobot.com/nozzle-cleaning
https://rigid.ink/pages/ultimate-troubleshooting-guide
https://www.simplify3d.com/support/print-quality-troubleshooting/
(https://wiki2.arcoslab.org/doku.php?id=tutorials:impresora3d)