This checkbox is available on the Milling page of certain finish operations. For projection milling methods, it toggles the way that you specify how far the tool moves over between passes. With Scallop height unchecked, you specify the stepover. With it checked, you specify the scallop height.
For Z-level finish operations it toggles how you specify how the tools moves down in Z. With Scallop height unchecked, you specify the Z-increment. With it checked, you specify the scallop height.
With scallop height checked, spacing of the toolpaths are calculated along the surfaces to provide a uniform surface finish. These figures show surfaces cut without using scallop height,
This figure shows the same surfaces cut with scallop height.
