ENLARGED DETAIL VIEWS
While prints may be drawn to a reduced, full, or enlarged scale size, parts are often shown in an enlarged scale. The enlarged portion of the part, also called the enlarged detail, is shown as an additional view usually located near the principal view to which it applies, Figure 7.9. The enlarged detail provides more space in which to apply dimensions and makes it easier to interpret the details of the area shown. Each enlarged detail is identified by a letter or number. The same letter or number is also used to identify the point on a principal view to which the
detail refers. FIGURE 7.9 ■ Enlarged detail of a portion of a part.
A developed view, also called a development, is a view of a part as it appears when stretched or laid out on a flat surface. This view shows the part before it is shaped by bending, rolling, or other fabrication methods. A developed view illustrates the part exactly as it must be prepared before any bending or rolling is performed, Figure 7.10. It may be very simple and involve only one bend, or it may be quite complicated and contain a series of bends, curves, and angles. It is common practice to show the location of any bends on the developed view. In addition, dimensions shown on the developed view include any allowances necessary for bending or rolling.
FIGURE 7.11 ■ Drawing of a tank including the developed view of the shell.
A developed view is also used to indicate the locations of holes in sheets or plates that are to be rolled or shaped into cylindrical forms, Figure 7.11. Hole sizes and location dimensions may be given either on the drawing of the part or on the developed view. It is not necessary to give the dimensions on both.
In many cases, a developed view is absolutely necessary. For example, the following shapes all require developed views for fabrication: fabricated angular pipe joints in which the sections are rolled from sheet or plate, and fabricated spheres, curved domes, or heads, Figure 7.12 and Figure 7.13. Note in Figure 7.12 that the dimensions added to the developed views follow the baseline system of dimensioning.
NOTE: FORMULA FOR STRETCH OUT 3.14 (Pi) or ъ X10M (Dia.)
31.40" S. O. (Stretch Out)