An essential feature of the AISA screen printing machines is the constant squeegee blade height. In all AISA screen printing machines, the rubber blade of the squeegee bar is supported by an aluminum extruded bar that is clamped to a reference point. The same reference is used in the squeegee sharpener GHS 18 and GHS 19. The sharpener ensures the parallelism of the squeegee, which is necessary to achieve a correct printing process. The rubber is manually pulled out from the bar by approx. 1 mm and then is sharpened. The machine has been designed to keep the height of the rubber blade constant. Therefore, the distance between the reference point (latching position of the squeegee bar) and the edge of the blade is always constant. This feature, together with the concept of machine-tool used in the design and manufacturing of the screen printing machines, allows a constant printing angle, the hardnes of the blade and the interference with the glass being equal. The squeegee sharpener can have different length according to the maximum squeegee length used on the printing machine.