Cutter apparatus for a crop material baler has a rotor carrying a series of blades and a knife bed having a series of knives, with the knives arranged to project up between the blades so that as the blades rotate, the blades pass on opposite sides of knives and sever the crop materials. The knife bed includes a cross shaft and an indexing shaft extending substantially the full width of the knife bed. Biasing mechanisms spring-load the knives. Each biasing mechanism has a roller contacting its respective knife and a roller support mounted on the indexing shaft with a rubber torsion spring. Each knife is configured to swing down about the cross shaft against the biasing force of its torsion spring in the event that an obstruction or solid object passes through the cutting zone and engages the knife.
