There are some areas where the 20 mm tool did not fit. Remove more of the remaining material in those areas with a Pocket rest milling operation.
3D Milling panel
Pocket
.
button.
to close the Tool Library dialog. Next, remove the material the previous operation did not remove.
at the bottom of the Operation dialog box, or right-click in the graphics window and select OK from the marking menu, to automatically start calculating the toolpath. The toolpath is now calculated and a preview appears in the graphics window.

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