A head with threads and blades of a rotary motor lawn mower or scythe, wherein the head comprises a base disc (1), a fastening disc (3) concentrically arranged on the base disc (1), threads (5) and blades (6), wherein the blades (6) are arranged in a rotary manner with their drilled holes (7) on plugs (8), whereas the threads (5) are arranged in two holes (10) on the blades (6) and secured against falling out of the holes (9, 10) with a thickening (12).