Abstract: The adjustable boring bar developed for metal working, and equipped with hard metal shifting tips consists of a boring bar shaft connected to the machine-tool, of a boring head adjustably guided as compared to the boring bar shaft and provided with shifting tip, as well as of elements fastening and adjusting the boring head. The boring bar shaft is provided with cylindrical bore including an angle with the symmetry line, as well as with radial slot, in the said bore a cylindrically developed boring head is located, on the cylindrical mantle of which flattening is to be found. Normal to the slot, setting and clamping element -- e.g. pinned adjusting screw -- is located. In the boring head, parallel to its centerline, an adjusting screw serving for the rough adjustment is to be found, whereas in the boring bar shaft a stop element -- e.g. a dowel pin -- of this adjusting screw can be found.