Multiple boring head

In a machine tool the combination comprising a housing, a spindle journalled in said housing for rotation about a first axis, drive means for rotating said spindle, means for supporting a workpiece in axial alignment with said first axis, means for moving the spindle and workpiece support axially relative to one another, an annular member fixed axially on said spindle for rotation therewith, said annular member also being rotatable relative to said spindle about a second axis parallel to and spaced from said first axis, a first tool holder fixedly mounted on said annular member for rotation therewith, a cutting tool mounted on said first tool holder such that, when the annular member is rotated relative to said spindle, said cutting tool is shifted radially toward and away from said first axis, a second tool holder mounted on said spindle for rotation therewith and for radial movement thereon, a cutting tool mounted on the second tool holder and having a cutting point thereon, means connecting the second tool holder and the annular member such that the second tool holder and the cutting tool thereon are displaced radially on said spindle toward and away from said first axis in response to rotation of the annular member relative to the spindle, and means for incrementally rotating the annular member about said second axis relative to said spindle while the spindle is rotatably driven about said first axis to simultaneously displace both the first and second mentioned tools radially relative to said first axis.