Usage Notes on Offset Face Method to Create Midsurface Features
Using the Offset Face method, you are able to define all the faces to be offset. You need select a Seed Face; out of which all the faces connected to the seed face satisfying the smoothness criterion and within the defined Boundary Faces will be offset half the thickness and into the solid.
The boundary face is defined automatically using a preset system. This system calculates whether a given face has an edge which is connected to a face, and that the normals on the two faces are about 90 degrees apart. This connected face is defined as a boundary face when the face contains the edges in the thickness direction. For sheet metal parts, only the cutting edges will have this condition, and the rest of the internal edges should always have blends.
The thickness to be offset is calculated using the seed face. The distance between the seed face and its opposing face is taken as the thickness of the solid. A dialog item (Midsurface Position slider bar) specifying the percentage of the offset will allow you to define the midsurface location. A 0% position means that the midsurface is at the location where the seed face is; a placement of 100% means that the midsurface is at the location of the opposing face; and the number between 0 and 100 means that the midsurface is in between the seed face and its opposing face. This thickness will be saved as an attribute of the midsurface feature; however, you will not be allowed to edit it because thickness is a physical property.
After all the faces to be offset are defined, they will be offset in accordance with the percentage number specified into the solid, and the new midsurface will be created there. The resulting midsurface will consist of one full sheet body.