V.A. Khomenko, Prof., Dr. Sc.(Eng.), V.V. Khomenko, Dr. Sc.(Eng.), lecturer, I.I. Polzunov, Altai State Technical University A system of measures is described aimed at modernizing the drilling tools for large-diameter engineering boreholes to enhance the tool endurance and to further improve drilling process characteristics. The modernized item is a reamer drill steel, namely, a set of 0.414 to 0.788 m discs.