Abstract: A press is described for prehemming and final hemming the internal periphery of an aperture in sheet material received on an anvil (10) on which the sheet material (12) is held down so that the upturned edge (14) of the aperture which is to be hemmed is substantially in alignment with the edge of the opening in the anvil (10). A composite hemming tool (40, 42) is provided adapted to perform prehemming and final hemming and carried b a tool carrier (36, 38). Drive means (24, 26) protrudes up from the press through the opening in the anvil so that a lower inclined leading edge (44, 46) of the tool substantially registers with the upturned edge (14) to be hemmed. The drive means operates so as to force the tool first of all towards the edge so as to bend the upturned edge over until it is bent through substantially 90 degrees from its upstanding position and thereafter to move in a generally downward direction so as to compress the downturned ege. A method of hemming is also described based on this machine.