The screws have a pitch of 250 micron/turn, however, the spring mechanism introduces a small >1 scaling factor to the actual travel, if you depend on ~10micron precision over long travel ranges, simply measure the actual tetrode depth during plating after a known number of turns relative to 0.
For the new shuttle drive see the paper for a travel distance estimate.
initial calibration:
During the implant, i usually keep the 2 corner tetrodes out by ~250um - i can then use pictures of these taken during insertion to register my guide tube array to pictures taken after the craniotomy in which i have scale bars - this way i know exactly where the drive went.
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