Since 2010 the CMD-3 detector has been collecting data at the e+e- collider VEPP-2000 in the Budker Institute of Nuclear Physics. One of the main goals of experiments with CMD-3 detector is the precise measurement of the cross sections of the e+e- annihilation into hadrons. For a large number of processes the main source of systematic uncertainty in cross sections determination due to accuracy of polar angles determination of the tracks. Z-chamber is used for the reconstruction of the track longitudinal coordinate which is with low systematic uncertainty. The measurement of longitudinal coordinates is performed by the collecting of the charge which is induced on the strip cathodes of the Z-chamber. The algorithms of the reconstruction of cathodes clusters and calibration procedure are presented.