[felixhuttmann]

Your STM is missing a proper approach mechanism. The vertical range of the piezo that is used for scanning will only be a few 100 nanometer. A screw is too coarse for that! Stick-slip mechanisms with a ramp (Besocke or Beatle-type STM https://www.researchgate.net/figure/1-Diagram-of-the-Besocke... or page 25 of https://www.bgc-jena.mpg.de/bgc-mdi/uploads/Main/MoffatDiplo...) are one solution. Even with such a mechanism, the 'approach' phase takes many minutes!