SEGMENT 8: Supplemental Views
Section Drawings
Half Section
A half section is one-half of a full
section. While a full section shows the object as if half has been cut away, a half section shows one-quarter cut away. Offset Section
The cutting plane of a section is usually
taken straight through the object. However, it can also be offset, or shifted, to show a detail or avoid a part. See Figure 8-10 for this type of section, known as an offset section. The cutting plane in this figure is offset to pass through the two bolt holes. If it were not, the bolt holes would not show in the sectional view. Show an offset section by drawing it on the cutting-plane line in a normal view. |
Full Section
A full section is a sectional view that
shows an object as if it were cut completely across from one end or side to the other. Broken-Out & Revolved Sections
A view with a broken-out section shows
an object as it would look if a portion of it were cut partly away by a cutting plane and then “broken off” to reveal the cut surface and insides. Think of a cutting plane passing through part of an object, as shown in Figure 8-13A. Now think of that cut surface as revolved 90°, so that its shape can be seen clearly, as shown in Figure 8-13B. The result is a revolved section (also called a rotated section). |
Chapter 8 Additional Information
Section 8.1
Sectioning techniques are available for
board drafting and CAD to help save time in creating sectional views. Accurate sectional views can be drawn with board techniques by using section line spacing and outline sectioning. To develop a sectional-view drawing, first determine which normal views are neces- sary. Then decide what type of sectional view is needed to show interior detail with few, if any, hidden lines. In CAD, section lining is often referred to as hatching. When developing sectional views, planning is important to maximize efficiency. |
Section 8.2
Sectional views are used to show complex
interior details. Special section-lining patterns, or symbols, are used to represent specific materials. Each of the various types of sectional views has a specific purpose; these views should not be used interchangeably. Cutting-plane lines or centerlines may be used to show where a section is taken. Hidden lines are used on sectional views only if they are needed for clarity. Bolts, shafts, pins, and other similar parts are usually not sectioned even if the cut- ting plane passes through them. |
Auxiliary Views
Auxiliary Views
Chapter 9 Vocabulary
Auxiliary View- An auxiliary view is a projection on an auxiliary plane that is parallel to an inclined surface.
Auxiliary plane- An imaginary plane adjacent to a surface that appears foreshortened in the normal views.
Primary auxiliary view- An auxiliary view that is developed directly from one of the normal views.
Partial auxiliary view- An auxiliary view in which some elements have been left out.
Edge view- A view in which a cutting plane appears as an edge, or line.
Reference planes- Planes that are parallel to inclined surfaces and are used for creating auxiliary views.
Auxiliary plane- An imaginary plane adjacent to a surface that appears foreshortened in the normal views.
Primary auxiliary view- An auxiliary view that is developed directly from one of the normal views.
Partial auxiliary view- An auxiliary view in which some elements have been left out.
Edge view- A view in which a cutting plane appears as an edge, or line.
Reference planes- Planes that are parallel to inclined surfaces and are used for creating auxiliary views.
Chapter 9 Additional Information
Section 9.1An auxiliary view is required to solve
problems involving inclined surfaces. A partial auxiliary view is acceptable when some curves can be left out but the object is still described completely. A primary auxiliary view is one that is developed directly from the normal views. Secondary auxiliary views are projected from primary auxiliary views. Drawing an auxiliary section is another way to explain an object’s details. Auxiliary views are developed by revolv- ing the plane of projection. The creation of an auxiliary view in CAD is similar to that used in board drafting but can be done in less time because the CAD software automates many of the more time-consuming tasks. |
Section 9.2A view projected from a primary view is a
secondary auxiliary view. It is used to find the true size and shape of a surface that lies along an oblique plane. An oblique plane is one that is inclined to all three of the normal planes. The steps used to construct a secondary auxiliary view are to draw partial and top views; project lines perpendicular to the inclined line in the top view and draw the primary auxiliary view. Then project lines perpendicular to the auxiliary surface of the primary auxiliary view and draw the second auxiliary view. Complete the top view by projecting lines from the top view and distances. Darken all lines and add dimensions and notes to complete the drawing. |