need education. Offset normal, offset automatic, offset translate

[texaspete]

Hello gang. It's me Texaspete. I've ran into another problem. I got optics from our optics engineer and I need to offset for the backside (side b, or the crude side) of the part. The optics have steps, these steps are flats between the optics. The flats are triangles and these crisscross. When I try to offset "normal surface" the software tries to extend the optics surface - but it can't and complaints about the triangle and not being able to extend the surface to the next intersection (BOY DO I WISH I COULD SHOW YOU A PICTURE). So I have been experimenting with "Normal to surface" "Automatic" and "Translate x,y,z" The offset value is 2.5mm. Normal doesn't work so I tried Automatic; First I offset one optical surface 2.5mm. then I offset the same optical surface using "automatic" When I cut a cross section the distance between the section entities varies, example. 1.4mm to 3.1mm. If I try translate x,y,z. I get simular values (not exact) but not exact as "automatic".
Can someone educate me about "Automatic" and "translate".
Thanks - southern style Texaspete