24 Machine Drawing
dharm
d:\N-Design\Des2-1.pm5 Seventh Print
2.6.4 Half Section
Symmetrical parts may be drawn, half in plain view and half in
section (Fig 2.23).
2.6.5 Local Section
A local section may be drawn if half or full
section is not convenient. The local break may
be shown by a continuous thin free hand line
(Fig. 2.24).
2.6.6 Arrangement of Successive Sections
Successive sections may be placed separately, with designations for both cutting planes and
sections (Fig. 2.25) or may be arranged below the cutting planes.
A
A
B
B
D
C D
C
A–A B–B C–C D–D
Fig. 2.25 Successive sections2.7 Conventional Representation
Certain draughting conventions are used to represent materials in section and machine elements
in engineering drawings.
2.7.1 Materials
As a variety of materials are used for machine components in engineering applications, it is
preferable to have different conventions of section lining to differentiate between various
materials. The recommended conventions in use are shown in Fig.2.26.
2.7.2 Machine Components
When the drawing of a component in its true projection involves a lot of time, its convention
may be used to represent the actual component. Figure 2.27 shows typical examples of
conventional representaion of various machine components used in engineering drawing.
Fig. 2.24 Local sectionFig. 2.23 Half section