Chapter 9:

3D Toolpaths

Upon successful completion of this lesson, you will be able to:

• Explain how 3D tool compensation is calculated.
• Describe 3D cut tolerances.
• Identify geometric features common to 3D tool paths.
• Explain the purpose, general parameters, and use of common 3D roughing tool paths.
• Explain the purpose, general parameters, and use of common 3D finishing tool paths.
• Explain the purpose, general parameters, and use of REST mill tool paths.
• Explain the purpose, general parameters, and use of Pencil mill tool paths.

Contents

• 3D Cutter Compensation
• Tolerances
• 3D Toolpath Setups
• 3D Roughing
• Parallel Finish
• 3D Scallop
• REST Milling
• Pencil Toolpaths
• Conceptualizing 3D Toolpaths

Overview

3D tool paths are used to machine non-prismatic parts such as molds, dies, and organically shaped consumer products. These parts may be composed of hundreds or thousands of faces.

CAD/CAM software creates 3D tool paths by first triangulazing the model, as shown in Figure 9.1 (though the mesh is far finer than shown in this illustration). This mesh is used to calculate the tool path based on tool size and shape.

3D tool paths are calculation intensive in part because of the extensive checking required to ensure the tool does not gouge the part as it moves across the topography of part faces.

Figure 9.1: 3D Tool Path Calculation