The vertical saddle is divided into two parts. The rear part is rigidly connected to the HP-AAC device which is able to move it vertically with extreme precision and without backlash. HP-AAC is a device controlled by the CNC of the machine, through two brushless motors. In this way it is possible to modify the overall geometry of the cross travel according to the RAM position. The geometric compensation thus introduced DOES NOT deform the structures and this is one of the fundamental characteristics of the international FPT patent.