Method of manufacturing a knife blade for a cutter knife and cutter knife

A method of manufacturing a knife blade for a cutter knife of an agricultural harvesting machine, the method comprising:

• providing a blade blank, the blade blank having a polygonal shape forming a rectangular mounting portion and a tapered blade portion, wherein the blade blank has a bottom side extending in a first plane and a top side extending in a second plane, wherein a hole connecting the first plane with the second plane is made in the blade blank,
• reshaping an area surrounding the hole of the blade blank by deforming in such a way that a top contact surface surrounding the hole is formed in a third plane, wherein the third plane is more distant from the first plane than the second plane in a normal direction perpendicular to the first plane, the top contact surface being adapted to be mounted to a knife rail,
• wherein in the reshaping step a peripheral rim is formed concentrically around the hole on the bottom side of the blade blank so that the peripheral rim is arranged in the normal direction between the first plane and the second plane, and
• wherein in the reshaping step a bottom contact surface is maintained around the hole on the bottom side of the blade blank so that the bottom contact surface is arranged in the first plane, the bottom contact surface being adapted to be mounted to the knife rail, wherein the blade blank is adapted to be fastened alternately with the top side or with the bottom side towards the knife rail.