Numerical control system

Claim 1

A numerical control lathe, comprising: a tool holder having at least two sides which intersect, said at least two sides of said tool holder each holding a cutting tool; means for moving said tool holder in the directions of the three mutually orthogonal X, Y and Z axes; means for supporting and rotating a workpiece to be machined by the tools attached to said tool holder about an axis extending in one of said directions, one said tool extending toward the workpiece in a second of said directions, and another said tool extending toward the workpiece in the third of said directions; memory means for storing positional data relating to the position of the tips of the respective tools, including tool geometric offset and near offset amounts, and the diameter of the workpiece when said tool holder is at a reference point; means for selecting one of the tools to be used; and means for reading selected tool data and the diameter of said workpiece from said memory means, for computing the distance from the tip of the selected tool to the outer periphery of the workpiece, and for moving the tool holder to move the tip of the selected tool to the outer periphery of the workpiece, when the workpiece is to be machined by the selected tool.