This document discusses different types of sectional views used in technical drawings to show internal geometry and hidden details, including full sectional views, half sectional views, and offset sectional views. It describes how sectional views are indicated using a cutting plane line and arrows, and how cross-hatching is used to represent cut areas. Rules for sectional views are provided, such as only cross-hatching the cut material and not placing full lines over cross-hatched areas.

1. Sectional Standards and
Conventions

3. Answers
A 35 mm
B 46 mm
C 32 mm
D 11 mm
E 15 mm
H 49 mm
J 11 mm

4. SectionalViews
• The main purpose of a sectional view is to effectively communicate internal
information to enhance the viewer’s understanding of the part.
• There are several different types of section views that engineers use to
communicate internal geometry.
• Full sectional view
• Half sectional view
• Offset sectional view

5. Hidden Detail
• Sometimes an object features detail that are internal and cannot be
seen by viewing external surfaces.
• In these circumstances, orthographic drawing is vital in depicting
otherwise hidden detail.
• Hidden detail may appear on any of the featured views.

6. Hidden Detail
• Hidden details are indicted by a thin broken line. It is essential
that this line convention be followed so that the detail is clearly
understood and not mistaken for an outline.

8. Cross-sections
• The cross-sectioning of an object allows for the internal details to be clearly
shown.
• A cross-section is literally a ‘cut-through’ view of an object.

9. Cross-sections
An imaginary cut is
made at an appropriate
point to display the
relevant information.

10. The cutting plane
• The path of the imaginary cut is indicated on the orthographical drawing by
a cutting plane.
• The cutting plane is shown as a broken line with thick lines at each end.
• Narrow arrowheads touch the end of the cutting plane, indicating the
direction of the cut and the subsequent direction of view.

11. The cutting plane
The first cross-section is always
labelled Section A-A, subsequent
sections are B-B, C-C and so on.

12. Crosshatching
• In order to show solid areas of
the object that have been ‘cut’,
hatching is used
• The hatching should be drawn
at 45° and be suitably spaced
relative to the area covered.

13. Crosshatching
• Where adjacent parts of an object meet, the direction of hatching should be
reversed.

14. Full sectional view
• A full section view is created by running the cutting plane through the entire
length of the object being sectioned
• The cutting plane may be identified and indicated in the usual manner to
increase clarity.

16. Half sectional views
• A symmetrical object or assembly may be drawn as a half section, showing
one half up to the centre line in section and the other half in full view
• The cutting plane effectively removes a quarter of the object
• A normal centreline is listed on the section view.The wording, half section,
can be confusing because one thinks of showing half the part.
• Remember, a half section shows one-fourth of the part, not one half!

17. Half sectional views

18. Offset sectional view
• In order to include features that are not in a straight line, the cutting-plane
line may be offset or bent, so as to include several planes or curved surfaces
• An offset section is similar to a full section in that the cutting plane extends
through the object from one side to the other.
• The change in direction of the cutting-plane line is not shown on the
sectional view.

19. Offset sectional views

20. Rules to remember
• A sectional view shows the part of the component in front of the sectional
plane arrows
• Only the material which has been cut by the sectioning plane is cross-
hatched
• A sectional view must not have any full lines drawn over cross-hatched areas
• Dimensions are not inserted in cross-hatched sectioned areas