US Patent 8931174 Methods and arrangements relating to edge machining of building panels

A tool configuration incorporating a preprocessing step and a method incorporating the tool configuration with its preprocessing step, producing an improved locking system of a floor panel. With the special tool configuration, and the preprocessing step changing the properties of the surface layer, certain surfaces are profiled of the joint edge of the floor panel, resulting in decreased tolerances. Further, equipment having an upper belt or chain guided in a horizontal direction, by an upper guiding device, and configured to press the floor panel vertically towards the lower chain, decreasing the tolerances of the produced floor panel as well.