A paper cutter assembly for a printer/plotter is mounted on the printhead carriage for movement therewith to avoid separate mounting and guide structure. A cutter wheel is mounted in a housing for cam induced movement between a raised inactive position and a lower active position by engagement of a cam element carrier mounted for movement in the cutter housing with structure on the printer chassis. The printer platen has a stationary cutter bar which extends in a channel in the platen transversely of the path of paper movement and has a cutter wheel receiving well at one end of the channel into which the cutter wheel drops without contacting the platen or cutter bar at commencement of a cutting operation. Camming surfaces on the platen engage the side of a cutter drive wheel to move the cutter wheel into engagement with the cutter bar and then to raise the cutter wheel to the proper amount of operational overlap of the cutting edges as the cutter assembly moves across the paper path. The cutter wheel is moved between its inactive and active positions at one side of the media and damage to the cut edge of rollfeed media is prevented by retracting the rollfeed media edge away from the cutter bar as the cutter wheel returns to said one side of the media after a cut.