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Sometimes the total auxiliary view is not needed.
Such a view could possibly even make the drawing
confusing. In this case, a PARTIAL AUXILIARY
VIEW is used. Only the points or lines
needed to project the line or surface desired are
used. This reduces the number of projection lines
and greatly enhances the clarity of the view. If
a partial auxiliary view is used, then it must be labeled
PARTIAL to avoid confusion. In figure 5-24,
if only the true length of line AB is desired, the
points A and B would be projected and connected.
The view would be complete after it was
labeled and dimensioned. In some cases the shape of an object will be such that neither the normal orthographic view nor the auxiliary views will show the true size and shape of a surface. When this occurs, a SECONDARY AUXILIARY VIEW is needed to describe the surface. The procedures for projecting and drawing a secondary auxiliary view are the same as those for a normal (or primary) auxiliary view. The reference plane for a secondary auxiliary view is located in the orthographic view from which the primary auxiliary view is projected. Usually, the primary auxiliary plane becomes the secondary reference plane. The secondary auxiliary plane is in the primary auxiliary view, and its location is determined in the same manner that the primary auxiliary plane is determined.AUXILIARY SECTION. An auxiliary view maybe a sectional, rather than a surface, view. In the upper left part of figure 5-26, there is a single-view projection of a block. It is desired to show the right side of the block as it would appear if the block were cut away on the plane indicated by the dotted line, the angle of observation to be perpendicular to this plane. The desired view of the right side is shown in the auxiliary section, which is projected from a front view as shown. Because the auxiliary plane of projection is parallel to the cutaway surfaces, these surfaces appear in true dimensions in the auxiliary section.A regular multi-view of an orthographic drawing is one that is projected on one of the
Figure 5-26.-Use of an auxiliary section. regular planes of projection. An auxiliary view is one that is projected on a plane other than one of the regular planes.A rectangular object is in normal position for regular multi-view orthographic projection when each of its faces is parallel to one regular plane of projection and perpendicular to the other two. This is the case with the object shown in figure 5-27, view A.USE OF REVOLUTIONS. In a REVOLUTION, the object is projected on one or more of the regular planes of projection. However, instead of being placed in normal position, the object is revolved on an axis perpendicular to one of the regular planes.Figure 5-27, view B, is a three-view multi-view projection showing the block in 5-27, view A, as it would appear if it were revolved 30 degrees on an axis perpendicular to the profile plane of projection. Figure 5-28, view A, shows how the
Figure 5-27.-A. Multi-view view of block in normal position; B. Multi-view view of block revolved 30 degrees on axis perpendicular to vertical plane.
Figure 5-28.-Use of revolution on axis perpendicular to (A) horizontal plane and (B) vertical plane.
Figure 5-29.-Use of a revolved section (A-A). block would look if it were revolved 30 degrees on an axis perpendicular to the horizontal plane. Figure 5-28, view B, shows the block as it would appear if it were revolved 30 degrees on an axis perpendicular to the vertical plane. |
 
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