This International Standard specifies the dimensions of milling cutters intended for manufacturing Woodruff keyseats in accordance with ISO 3912. Two types of Woodruff keyseat cutters with cylindrical shank are specified: — Woodruff keyseat cutters with cylindrical shank, in accordance with ISO 3338-1 ; — Woodruff keyseat cutters with flatted cylindrical shank, in accordance with ISO 3338-2.