sometimes its very helpfully to can adjustable the z-axis manually. range: -6 mm ( be carefully ) +9mm You need: the two plastic parts 2x M3 square nuts M3 threaded rod ~100mm long 2x 3mm steel shaft ~5mm long (or 3mm nails) 2x 3x8mm steel screws added knob, there are two differend versions available: ver1 = for allen screw (Madenschraube) ver2 = for cylinder head bold ( Zylinderkopfschraube mit Schlitz)