2D Spiral toolpaths mill a feature in a continuous spiral either towards the feature center or away from the feature center. Spiral is only a general description of the actual path as not all feature shapes lend themselves to a truly spiral pattern. The pattern is obtained by taking the stock boundary, the feature boundary or the curve specified in the Boundaries tab and offsetting this curve toward the center of the part. The steps between the passes is calculated in 2D. For spiral toolpaths that use a 3D stepover use the 3D spiral technique. To use the stock boundary, click Use stock dimensions as boundary on the Boundaries tab. This will result in a square shape to the toolpaths.
To automatically calculate the silhouette boundary of the surfaces of your feature, click Use part surfaces as boundary. This toolpath will mimic the boundary of your feature.
If you want to use a different curve as your toolpath shape, click Use a curve as boundary on the Boundaries tab. The options for using a curve are different for spiral milling and other techniques.
For information about 3D Manufacturing attributes, refer to 3D Milling tab and Manufacturing attributes. See also Troubleshooting projection milling methods.