This function offsets the surface along its surface normals. You may need to reverse the surface normals to get the offset you desire. Surface offset is an approximate operation.
You must have an existing surface to use Surface normal offset.
Open the Surface wizard and set it to perform a Surface normal offset or select Surface normal offset from the surface toolbar.
Set whether you want to modify the existing surface or create a new surface from the process.
If you are creating a new surface, name the surface for future reference.
Click Pick and select the source surface, or select the surface from the dropdown list box.
Set the distance you want to offset the surface.
Specify an acceptable Tolerance. Tolerance means that the resulting surface may deviate from the exact offset by no more than value you enter.
Click Finish or OK to create the new surface.