1. SECTION VIEWS Drawing and Sketching (Continued) Lecture 13B
Engineering Design GE121
SECTION VIEWS
Drawing and Sketching
(Continued)
Lecture 13B

2. Sections
Sections are views of surfaces exposed by cutting planes

3. Conic Section
Different sections are created by varying the angle of the cutting plane.
Circle Ellipse Parabola Hyperbola

4. Mechanical Drawing Section

5. Assembly Drawing

6. Construction Detail Sections

7. Topographic Maps

8. Topographic Sections

9. Topographic Sections (on Mars)

10. Wireframe Sections

11. Section Views in Engineering Sketches
Improve clarity and reveal interior features of parts
Eliminate (or greatly reduce) hidden lines so sketches are more easily visualized and understood
The following section views images are taken from: Bertoline(1999): Introduction to Graphics for Engineers, McGraw-Hill

12. Section Views in Engineering Sketches
Based upon the use of a cutting plane that cuts through the object to reveal interior surfaces
Line of Sight Imaginary Cutting Plane

13. Section Views in Engineering Sketches

14. Section Views in Engineering Sketches
Normal Orthographic View Section View
Section View can replace one of the normal orthographic views, or it could be drawn as a separate view

15. Section Views in Engineering Sketches
Ideally the objective is to eliminate all the hidden lines on the section, but it’s not always possible

16. Section Views in Engineering Sketches
Hidden lines used to avoid an additional view

17. Section Views in Engineering Sketches
Cutting plane is indicated as an edge view in one of the orthographic views (cutting plane line)
Labeled
Thick line (0.6mm), dashed line, which extends beyond the edge of the object & terminates with arrowhead at 90° to the cutting plane
Two types of dashed lines
Arrowheads indicate the direction of view or line of sight

18. Section Views in Engineering Sketches
Bottom right sketch should be mirror image of that on the left.

19. Section Views in Engineering Sketches
This shows the kind of detail that goes into defining standard drawings.
Two Cutting Plane Line - Formats

20. Section Views in Engineering Sketches
All surfaces touched (cut) by the cutting plane are marked with cross hatching or a special hatching symbol
Generic hatch pattern is normally at 45° unless object edges are at 45 (never want hatching to be parallel or perpendicular to object edges. If necessary, change angle of hatch to avoid this)

21. Section Views in Engineering Sketches
Hatching symbol can be used to convey information about the material of the object.

22. Section Views in Engineering Sketches
More hatching symbols

23. Section Views in Engineering Sketches
Section lines are omitted around notes and dimensions

24. Section Views in Engineering Sketches
Full Section
Cutting plane passes through the object in one continuous line

25. Section Views in Engineering Sketches
Half Section
Cutting plane passes only half way through the object, then takes a 90° turn
Generally for symmetrical objects

26. Section Views in Engineering Sketches
Hidden lines ideally omitted on both halves of the section view
The sectioned and unsectioned portions are separated with a centreline
Cutting plane uses one arrowhead only

27. Section Views in Engineering Sketches
Offset Section
Cutting plane line which is bent at 90° angles at one or more locations in order to pass through important features

28. Section Views in Engineering Sketches

29. Section Views in Engineering Sketches
Change of angle of the cutting plane line is NOT shown in the section view

30. Section Views in Engineering Sketches
On multi-part assemblies, change the angle of hatching or hatching material symbol to identify different parts

31. Section Views in Engineering Sketches
Sketching and Drawing
Sketching is a less-exact freehand operation, and straightedges are not generally used
Drawing is more precise, and uses straightedges, and precise dimensions and angles

32. Activity: Sketch Section
Section View will replace Top View
Start by reproducing the drawings shown here. Note that the End View lines up with the Front View.
Adding the Top View may make it easier to visualize the Section View.
Front View Right Side View

33. Activity: Sketch Section
Top View
Front View

34. Activity: Sketch Isometrics
Sketch Isometric Views of the Objects in the previous examples as time permits