accordance with the foregoing a plurality of cutter discs are positioned in stacked face to face relationship on the center section of the mandrel each with its key slot 50 disposed in engaging relationship with the helical key 46 such that the individual helical cutting edges of each disc is rotationally indexed from the adjacent disc in an amount so as to position the cutting edges in helical alignment forming the substantially continuous segmented helical cutting edge 26 as shown in fig1 the plurality of discs are maintained in stacked relationship along the mandrel with their side faces 60 in appropriate abutting relationship by means of a pair of removable circular clamping flanges 70 which slidably overlie the end shafts 32 as best shown in fig1 and 2 and are secured by means of machine screws 72 in tapped bores 74 provided in the radial shoulders at each end of the center section 30 to assure the maintainence of appropriate clamped relationship of the stacked discs it is preferred that the length of the cylindrical center section 30 of the mandrel be slightly less than the total length of the stacked discs such that at least one clamping flange 70 is disposed in a slight axially positioned clearance from the radial shoulder of the center section it will be appreciated from the foregoing description that the rotary cutter assembly is permissive of quick and simple repair in the event of inadvertent damage to the.