The wire is the only diamond tool whose support is not rigid, as this consists of a flexible steel cable. For this reason it is reasonable to assume that any shear stress to which it is subjected must be lower than could be sustained by a disc, a wheel, a drill and also by a frame-saw blade, which are fitted with a steel support. This premise implies that the cutting capacity of the beads and their self-dressing ability must be greater than in the diamond tools mentioned above, or that the diamond wire must be used with lower productivity parameters (m2 sawing/hour). Although this has already been said in past publications, it is useful to see a comparison between the use parameters by comparing a 1000 mm disc with a 21 m wire cutting class 3 granite. Leaving aside the analysis of the incidence of diamond and labour costs which are extremely negative for the wire (but are justified by the slab-squaring possibilities that discs do not have) and concentrating our attention on the cutting capacity (m2/hour) and the power consumption it would seem that everything that has been said in the foreword is completely inapplicable, i.e. that also by reducing the cutting capacity the stress on the bead is still greater than on segments. But things are not as they seem. In the same instant the disc, taken into exam with these cutting parameters, has practically only one segment in contact with the material and therefore the power per segment is 4 kW (with the relating stresses arising from this on the segment itself), while the beads in contact with the material are 120 so that the power for each bead is 0.066 kW (with the resulting relating stresses). Thus what was hoped for in the foreword occurs partly also in practice, but in a manner that is not exactly useful as far as self-dressing of the bead is concerned