Overview

In the previous chapter, the main focus was on evaluating a part contour and establishing contour points necessary to develop a suitable toolpath. This chapter continues that subject, with additional geometry solutions and with the focus on calculations using various shortcuts by employing formulas.

During toolpath development, it is quite common to define a typical contour as a combination of lines and arcs meeting at their respective endpoints. Some contours will have more lines or more arcs in some cases, they may have only lines or only arcs. In CNC programming, the approach to finding coordinate points (contour points) is generally the same, regardless of the line/arc combination within a contour. There are three main possibilities that will each require a little different approach by the CNC programmer, when developing the desired toolpath:

• Intersecting contour point between a LINE element and another LINE element

• Intersecting or tangent contour point between a LINE element and an ARC element

• Intersecting or tangent contour point between an ARC element and another ARC element

Regardless of the endpoint combinations, the tool cutting direction will be either in the climb milling mode or the conventional milling mode (predominantly climb milling mode).

In the majority of programming applications, the CNC programmer has to use some mathematical methods to establish the XY coordinates of the desired contour point.

Contour Point Between Two Lines (Lathe)

A contour point between two linear motions will always be an intersection. From the three available possibilities...