You may have selected the solid instead of just the surfaces you want machined.
Place the solid on a seperate level, and turn that level OFF ( un-tick ).
It is a good idea to used different colors as well.
( note-- you can also mask items for selection by lines, color, level, solids and/or surfaces )
Drive surfaces will be the surfaces you want the tool to touch .
Check surfaces are for to ensure tool does not go into.
Surfaces can be solid faces if you set the options correct, the default is solid block, which I think you have done. |