Abstract: A printing machine has a plurality of rubbing rollers which are rotatable about respective rubbing axes and serve to transfer ink to a form roller. Each of these rubbing rollers is connected via a link to a respective cam follower engaging in a respective continuous circumferential cam groove in a cam that rotates about an axis parallel to the roller axis. The cam follower is normally nonrotatable about the cam but its angular position about the cam can be adjusted so as to closely control the inking characteristic of the respective rubbing roller. The angular position of each rubbing roller is determined by means of a calculator which is set up to hold a diagram on which is plotted the inking density of the material to be printed against the form roller position. A plurality of sliders each corresponding to a respective rubbing roller are independently displaceable on the support adjacent the diagram and each carry indicia indicating the inking characteristic of the respective rubbing roller.