A manually operable cutter device for cutting flexible sheet material, the cutter device comprising a cutter body and a cutting blade assembly operatively mounted to the cutter body and including a rotatable cutter blade having a peripheral edge portion and a fixed cutter blade adapted to cooperate together to provide a cutting zone in which sheet material can be cut. The rotatable cutting blade is mounted for rotation about an axis which extends generally laterally with respect to a normal feed direction of the sheet material to the cutting zone and the direction of rotation of the peripheral edge portion through the cutting zone is in the normal feed direction. The tangential peripheral speed of the rotating cutter blade in the cutting zone is not less than the speed of the feed of sheet material to the cutting zone.teh