Auxiliary views

Views, Continued Auxiliary views Any view not projected onto one of the principal planes is an auxiliary view. A primary auxiliary view is a view projected to a plane perpendicular to one of the three principal planes (top, front, or side) and inclined to the other two planes. A view projected from a primary auxiliary view on a plane inclined to all three principal planes of projection is referred to as a secondary auxiliary view. The purpose of an auxiliary view is to show the true shape and size of an inclined surface of an object since inclined surfaces are not parallel to any planes in multiview projections and appear foreshortened. The method of projecting the image of an object to an auxiliary plane is identical to the method used for projecting an image to one of the principal planes; that is, the projectors are parallel and the observer is positioned an infinite distance away from the object. To draw a primary auxiliary view, follow this table: Step 1 2 3 4 5 6 . Action Draw two adjacent principal views, one of which must show the inclined surface as an edge. Lightly draw a reference line (AB) parallel to the edge view of the inclined plane. Lightly draw a reference line (CD) between the two principal views. Use AB and CD to locate points in the auxiliary view. Draw projectors from the inclined edge rotating reference line AB parallel with the inclined surface. These projectors are perpendicular to the inclined edge and the reference line as shown in figure 3-44. Using a compass or dividers, transfer distances from reference line CD to the various points in the side view. Darken all object outlines of the primary auxiliary view and erase all projectors and reference lines. The completed primary auxiliary view shows the true shape of the inclined surface. Continued on next page 3-49