To meet the increasing uncertainty demands for the calibration of tactile coordinate measuring machines the PTB aims to provide calibrated artefacts with an uncertainty in the range of 30 nm. Therefore, the Nanometer Comparator will be upgraded with a tactile sensor system to add the capability to measure step gauges. A concept of the integration of a tactile sensor into the machine setup is presented and two different sensors were analysed by repetitively contacting a gauge block face. With a sensor based on a silicon flexure and two fibre interferometers a (1) repeatability of less than 7 nm was achieved.