To set the machining, the technique commonly used is to measure dimensions between each machined surface and the one which locates the workpiece into the workpiece holder. This technique leads to dimensions with much smaller tolerances than the ones specified on the design drawing and to long time setting. On an example of a screw machining process we present the first stage of the Copilot-Pro methodology. It consists in identifying the groups of manufacturing operations which must be done before extracting the workpiece from the machine-tool to measure the surfaces achieved. Thus, the number of workpieces extracted from the machine-tool is minimized which reduces the setting times, the number of unfinished and rejected workpieces and which permit to select manufacturing dimensions with higher tolerances.