Material entry tool path for cutting a starting hole that extends in the vertical axis

An apparatus for generating control code for a CNC machine comprising:

• an arithmetic processor coupled to a memory, wherein the processor is programmed to generate the control code by:
• generating in a computer a first plurality of coordinate values, xi, yi, zi, said first plurality of coordinate values representing a plurality of first connected line segments which surround a vertical axis, said first connected line segments gradually descending to a first predetermined depth,
• generating in a computer a second plurality of coordinate values xj, yj, zj, said second plurality of coordinate values representing a plurality of second connected line segments which surround the vertical axis, said plurality of second connected line segments having a starting point at approximately the first predetermined depth, and gradually descending to a second predetermined depth greater than the first depth, and
• converting the first and the second coordinate values to a code for controlling the CNC machine,
• wherein, when said code is executed in said CNC machine, a milling cutter mounted to a spindle of the CNC machine forms in a workpiece, a first hole based on the first plurality of coordinate values and a second hole based on the second plurality of coordinate values such that a ledge having a width greater than a chip thickness is formed in the workpiece at a boundary of the first hole and the second hole.

A non-transitory computer readable storage medium with an executable program stored thereon, wherein the program instructs an arithmetic processor to perform the following steps:

• generating in a computer a first plurality of coordinate values, xi, yi, zi, said first plurality of coordinate values representing a plurality of first connected line segments which surround a vertical axis, said first connected line segments gradually descending to a first predetermined depth,
• generating in a computer a second plurality of coordinate values xj, yj, zj, said second plurality of coordinate values representing a plurality of second connected line segments which surround the vertical axis, said plurality of second connected line segments having a starting point at approximately the first predetermined depth, and gradually descending to a second predetermined depth greater than the first depth, and
• converting the first and the second coordinate values to a code for controlling the CNC machine,
• wherein, when said code is executed in said CNC machine, a milling cutter mounted to a spindle of the CNC machine forms in a workpiece, a first hole based on the first plurality of coordinate values and a second hole based on the second plurality of coordinate values such that a ledge having a width greater than a chip thickness is formed in the workpiece at a boundary of the first hole and the second hole.