Dear Dover, I need to mention that I was able so far to adjust my Arche to 1/306 s of a mm easily. If one handles the suppllied Allen key on the long lever, it works like
a minut (even seconds) of an analog watch. Very interesting to see how fine adjustable the M4 special fine thread is, if the indicator lever is long enough. Thus it indicates every fraction of a minut on an imaginated 'clock face' around the SRA screw. It is even fairly easy to return to previous settings to cross-check the sonic finding.I forwarded my findings to Daniel and he announced to add a printed dial indicator face to the SRA screw to allow precise repeatable settings.