1. CE En 112 Engineering Drawing with CAD Application
Chapter 3: Section and Auxiliary Views (Lecture A)
Section Views

2. Lecture Outline Sectioning basics (3.1, p.132)
Cutting plane lines (3.2, p.136)
Section line practices (3.3, p.136)
Section view types (3.4, p.138)
Special sectioning conventions
Next class

3. Objectives Apply the concept of cutting planes to create section views
Represent cutting plane lines and section lines, using conventional practices
Create full, half, offset, removed, revolved, broken-out and assembly section views using conventional practices
Create conventional breaks for different materials and cross sections
Represent ribs, webs, and thin features in section, using conventional practices
Represent aligned sectioned features, using conventional practices

4. Sectioning Basics (3.1)
Section view: An important aspect of design and documentation used to improve clarity and reveal interior features of parts and structures – also used to reduce the number of hidden lines in a drawing

5. Sectioning Basics (con’t)
Sectional drawings: Multiview technical drawings that contain special views of a part or parts—views that reveal interior features—using a minimum number of hidden lines

6. Sectioning Basics (con’t)
Traditional section views are created by passing an imaginary cutting plane through the object parallel to one of the primary multiview planes

7. Sectioning Basics (con’t)
Hidden lines are minimized as the section view reveals hidden features without the use of hidden lines

8. Sectioning Basics (con’t)
Edges that can be seen in section view need to be drawn as visible (solid) lines

9. Pay special attention to the direction of the arrows
Cutting Plane Lines (3.2)
Cutting plane lines: Show where the cutting plane passes through the object representing the edge view of the cutting plane adjacent to section view
Pay special attention to the direction of the arrows

10. Cutting Plane Lines (con’t)
Thick (0.6 mm or inch) dashed lines that extend past the edge of the object ¼” or 6 mm with line segments at each end drawn at 90 degrees and terminated with arrows
The arrows represent the direction of the line of sight and point away from the sectioned view
Two line types are acceptable for cutting planes

11. Section Line Practices (3.3)
Section lines (cross-hatch lines): Added to indicate the surfaces that are cut by the imaginary cutting plane
Different symbols are used to represent various materials
With so many different materials the general symbol (cast iron) is used in most instances

12. Section Line Practices (con’t)
General purpose line is drawn at 45-degrees spaced 1/16 to ⅛ inch (1.5 mm to 3 mm) depending on drawing size
Section lines should not run parallel or perpendicular to the visible outline

13. Section Line Practices (con’t)
Avoid placing dimensions or notes within the lined areas – if they must be placed there, omit the section line in the area of the note

14. Section Line Practices (con’t)
If an area is too large use outline sectioning
Thin parts in section are represented without section lines

15. Section View Types (3.4) Full section (Fig. 3.11)
Half section (Fig. 3.12)

16. Section View Types (con’t)
Broken-out section (Fig. 3.13)
Revolved section (Fig. 3.14)

17. Section View Types (con’t)
Removed section (Fig. 3.15)
Offset section (Fig. 3.16)

18. Section View Types (con’t)
Assembly section
Auxiliary section

19. Special Sectioning Conventions
Conventional practices have been established to handle section views of special situations including holes, ribs, webs, and other thin features
These are not in the text, however, a brief explanation will be included in the following slides

20. Special Conventions (con’t)
Thin features, such as webs, are left unsectioned when cut parallel to the feature by the cutting plane

21. Special Conventions (con’t)
Thin features are section lined with alternate lines if it clarifies the geometry of the object

22. Special Conventions (con’t)
Web
When the feature is not lost, section lines are omitted

23. Special Conventions (con’t)
Aligned section conversions are used to rotate the holes into position along the vertical center line

24. Special Conventions (con’t)
Aligning spokes in section views is the conventional method of representation

25. Special Conventions (con’t)
Conventional breaks: Used for revolved section views or for shortening the view of an elongated part
View shortened

26. Next Class How to create auxiliary views MD HW#3 is due
MD HW#4 is assigned