Bruce Mayer, PE Registered Electrical & Mechanical Engineer BMayer@ChabotCollege

1. Engineering 22 SectionViews-1 Bruce Mayer, PE Registered Electrical & Mechanical EngineerBMayer@ChabotCollege.edu

2. Learning Goals • Properly Create Section (Cut-Away) Views to Show Internal Features Of Objects That Are Not Easily Understood In Standard Orthographic Projection View Drawings

3. Learning Goals cont • Use and/or Apply • How & Where to Construct the Cutting Plane Line • Section Lines (a.k.a. “Hatch Lines”) • Several Types of Section Drawings

4. Section Views • Definition: An Orthographic Technical Drawing That Reveals Details About INTERNAL Features By Displaying The Part As If Cut By An Imaginary Plane

5. Section Views cont • Usefulness: • Makes the Drawing More Understandable, Especially The Internal Details Of The Part • Since The Sectioned Drawing Shows Internal Features There Is Generally NO NEED To Show HIDDEN Lines • Especially helpful for • Complex Part Fabrication • Assembly Drawings

6. Some Assembly Drawings

7. The Cutting Plane • An imaginary plane that defines where the object is cut • Shown in drawing ADJACENT to the Sectioned View • Drawn with the PHANTOM or HIDDEN line type • Arrows at the end of the cutting plane line indicate the direction of view for the sectioned drawing.

8. The Cutting Plane cont. • The arrows point TOWARD the part of the object that is VISIBLE in the sectioned view • A sectioned drawing follows the general rules of any view in an OrthoGraphic MULTIVIEW drawing

9. Multiple Cutting Planes • Cutting planes may be labeled at their endpoints if multiple cutting plane lines are used • When using multiple cutting planes each sectioned drawing is drawn as if the other cutting plane lines do not exist • The cutting plane line takes precedence over center lines • Cutting planes may by omitted when their location is obvious

10. Section View Placement • The Section View is Placed “Opposite” to the Direction of the Cutting Plane Arrows • The Arrows are Rotated INTO the Paper to Reveal the Section

11. Cross Hatch Lines • Cross-Hatch Lines are drawn where the object passes through the cutting plane • If a saw were used to cut the part then Hatch lines represent the cutting (tool) marks left by the saw blade • Different materials may be represented by the use of different Hatch line types • The general Hatch line type which may be used for any material is the line type for IRON

12. Hatch Line Conventions • Hatch lines should NOT be PARALLEL or PERPENDICULAR to object lines • Hatch lines are generally drawn at 45° unless this conflicts with other rules • Hatch lines should be oriented at different angles for separate parts • Occasionally Hatch lines are only drawn on the perimeter of large areas (not an issue with CAD) • Hatch lines are not used for thin parts rather they are filled in solid (Do not use closely spaced Hatch lines)

13. Section Line Conventions cont. • Cutting Plane Lines Take Precedence over Center Lines • Hatch Line Density • Should Clearly Identify the Cut Material • Not be Too Dense As This Tends to Obscure Object lines

14. Using the White Board, Let’s Make Some Cross Section Drawings Sketch Demo A B C

15. Prob-A Solution

16. Prob-B Solution

17. Prob-C Solution

18. All Done for Today Blue PrintCrossSec Circa 1862

19. Engr/Math/Physics 25 Appendix  Time For Live Demo Bruce Mayer, PE Licensed Electrical & Mechanical EngineerBMayer@ChabotCollege.edu

20. Prob-A Solution - 1 • Grid it

21. Prob-A Solution - 2 • Connect Dots to Block In OutLine

22. Prob-A Solution - 3 • Connect Dots to Reveal Sliced Edges

23. Prob-A Solution - 4 • Construct View of Rounded-End Slot • Circle • Trim • Pedit (turn ½-circles into Plines) • Pline

24. Prob-A Solution - 5 • Connect the Dots to Reveal Sliced Areas • Hatch the Sliced Areas

25. Prob-A Solution - 6 • Strip Out Constr Lines, and Add Center Marks & Lines to Show Completed Cross-Section

26. Prob-B Solution

27. Prob-B Solution

28. Prob-C Solution

29. Prob-C Solution