For producing forked roots of turbine blades, the turbine blades are, in a first step, roughed-in and smoothed on their outer faces in a single operation with two rigidly coupled disk milling cutters that are provided hard metal cutter inserts. The tool string includes a shock reduction tool, which includes an anchoring tail piece axially and rotationally fixed to the at least one tubular. The slots divide the substrate into an array of interconnected rectangular sections that are arranged in horizontal rows and vertical columns and which are interconnected by tabs.