Abstract: An apparatus for severing thin boards from squared timber includes a guide urface upon which a squared timber is conveyed and pressed against a cutting edge of a blade, as well as a counter pressing edge. The adjustment of the distance between the guide surface and a plane parallel thereto which extends through the blade cutting edge (i.e., the thickness of the thin board to be cut) is effected by relative adjustment of the blade cutting edge to the guide surface in an inclined plane which forms an acute adjustment angle .alpha. with a line normal to the guide surface. Because of the relative adjustment of the blade cutting edge to the guide surface along the angle .alpha., when a different board thickness is desired, the distance between the blade cutting edge and the counter pressing edge in the cutting direction is automatically adapted. In a preferred embodiment of the apparatus, the width of an exit guide channel for the severed thin boards can also be simultaneously set to the desired board thickness.