Abstract: A knife assembly for shearing angle stock has a square, plate-like, floating cutter provided with a pair of opposed, flat, parallel faces, presenting four, stock-engaging corners each having two pairs of cutting edges, permitting eight "settings" used successively as wear, breakage or dulling may require. Four rigid stops and a pair of floating abutments are provided so that during use, regardless of which of two directions the knife tends to rotate when engaging the stock, it is firmly backed up within a cutter-receiving recess formed in a shiftable cutter support.