amounts of power necessary to operate the apparatus because of the timing of the cutter rolls 14 and 16 relative to one another and the shallow depth of intermeshing of the cutter rolls 14 and 16 the cutter segments 78 and 80 overlap one another but not the central wheels 76 of the adjacent cutter discs thus avoiding erosion of the central wheels 76 beneath cutter segments 78 or 80 as a result the power required to operate the apparatus is not increased by scrap material catching between adjacent cutter disc central wheels 76 beneath the cutter segments 78 or 80 when the cutter segments 78 or 80 are worn the scrap shredding apparatus 10 of the present invention may be sharpened restoring cutting efficiency practically to its original level by removing each of the worn cutter segments 78 and 80 from its respective cutter disc central wheel 76 and removing material from each of the lateral surfaces 110 and 112 of the cutter segments 78 and 80 material is removed by grinding or milling to reduce the lateral width 104 of the cutter segment 78 or 80 to the designed thickness of a thinner one of the cutter discs 34 50 taking care that material is removed in such a way as to preserve the relationship between the lateral surfaces 110 and 112 and the centrally located bolt holes 82 this restores sharp edges on the cutter segments as shown in fig4 the cutter segments 78 and 80 are then fastened to the next thinner central wheel 76 whose thickness they match once the cutter segments have been thus sharpened and reinstalled on different central wheels 76 as part of the cutter discs 34 50 the cutter segments 78.