Auxiliary Views

     Auxiliary views are used to show the true lengths parts of objects that do not have faces parallel to the normal three viewing planes. Auxiliary view are folded up from a normal view into the viewing plane. In the image shown above, the view at the center shows a front view of the object. The object curves upward at each end. The top view shows the the object as seen from the top, but the features at the ends are contorted due to the fact that they are viewed at an angle. the circles have become ellipses, and lines do not show the true length or angle of the surfaces of the part. The three views on the sides help show the true lengths and shapes of the angled features. Features that would be contorted in a normal view are dimensioned in an auxiliary view instead. The view to the far right is a secondary auxiliary view, because it is folded up from another auxiliary view. The auxiliary views in this drawing are partial auxiliary views, because they do not show the entire object. Sometimes, a short break line is used to show where the object would continue if it were shown.
     Without Auxiliary views, tedious trigonometric calculations would be necessary to find the actual lengths of features at angles, and dimensions might have to be drawn to hidden lines more often, and features would not be dimensioned in their primary view.