Contour Parallel – Z constant Finishing (Waterline)

This function is used to create Z-level contours that can be machined using only X and Y motion. This permits the use of G17-planar arcs and greatly compresses 3D CNC code. It also allows much better surface finishing on vertical surfaces by using Z depths with the Side of the cutter, rather than the end. The contours are similar to the line that would be formed if the surface was partially submerged in water and a line was drawn where the water contacted the surfaces. Multiple uniformly incremented depths would be similar to the output from this surface finishing function.

A surface selection is required, along with optional stock box and restriction contours. The example below shows multiple complex surfaces with an outer and inner restriction curve. This permits machining of the steep sidewalls( at which this function provides the best cutting), while eliminating the flatter top surface. The top surface will then be machined using a more appropriate cutting strategy such as axis parallel, iso curve, or contour parallel finishing. No toolpaths are created by this function on a flat surface.

NC-3D Milling-Surface milling 3D-Constant Z constant finish

Tool Section

Select a tool from the tool table

Adjust Diameter D &E if desired

Set tool origin to tool tip or Center of the ball radius

NC-Path section

Set interpolation error initially to a large value such as .01 inch to speed up calculation of toolpaths. For the final toolpath, be sure to set this value just smaller than the desired surface finish tolerance.

Z-connections – Each “ring” that is developed by this function is independent from the next. The Z connections are used to connect between each Z level. If the part has already been roughed close to the desired shape, check the Z-incremental box, and the tool will rapid down close to the next ring. If the part has not been roughed, do not check the Z-incremental box and the tool will feed down to the next contour ring or waterline.

Surface section

Interpolation error – This value determines the coarseness of the surface interpolation. Set to a relatively large value such as .01 inches when testing the function. Use a value no larger than the stock distance to insure no gouging of the workpiece.

Stockdistance – Minimum amount of finish stock to be left after all cutting is completed.

Z-tooling section

Step Dz – This value determines the depth of cut per pass of the finishing cutter.

Above, front view of the toolpath. Note the uniform depth per pass of the cutter.

Below, rendering of a simulation of multiple surfaces from a previously roughed model.