VIEWS WITH CONVENTIONAL BREAKS

Many of the structural shapes to be drawn are too long to be shown on a print in their true size. In addition, the use of a reduced scale size would be impractical because it would be dif­ficult to show fine details. However, this could be overcome by showing an enlarged detail.

If the metal has a uniform structural shape throughout its length, a reduced length can be shown by means of a conventional break symbol. A break symbol indicates that a sec­tion of the metal has been removed. Figure 7.1 shows the conventional break symbols com­monly used on prints. The location where the metal has been removed is indicated by break lines. The amount removed is not given since it has no significance in the reading of the print. Figure 7.2 shows the break symbol in use on a drawing to reduce the amount of space required to show the object. Note that the part is dimensioned as if the entire part were shown.

Dimensions given on views that have a con­ventional break are the true sizes, as shown in Figure 7.2.

The shape of an object can be shown by the use of the break symbol. If appropriate section lining is used, the composition of the material can also be indicated. For example, in Figure 7.1 the conventional break symbol that illus­trates a rectangular section shows the shape of the section between the break lines. This method of showing the shape in section is often used for structural shapes such as chan­nels, S-beams, and T-shapes. The cross section shown for each shape is called a revolved sec­tion, Figure 7.3. Note in Figure 7.3 that the section lines indicate the composition of the structural shape. Revolved sections will be discussed in greater detail in Unit 8.