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

1. Engineering 22 SectionViews-2 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 Drawing Types • Full Section (done so far) • Half Section • Offset Section • Broken-Out Section • Revolved Section • Removed Section • Special Section Conventions

5. Full Section • The cutting plane passes completely through the part as a single flat plane

6. Half Section • The cutting plane only passes half way through the part • The other half is drawn as usual • Hidden lines are not shown on either half of the part • A center line is used to separate the two halves • Mostly used on cylindrical parts

7. Offset Section • The multiview drawing is often difficult to interpret when there are several hidden features on the object • A sectioned view makes the object much easier to understand • An offset section allows the cutting plane to pass through all of the significant internal features • There may be several bends/kinks in the cutting plane

8. Offset Section cont • The actual part would show a new visible line (at the edge) at the bend in the cutting plane • Since the cutting plane bend is arbitrary, do not show the line representing this bend in the sectioned drawing • Hidden lines are NOT shown • Be sure to include object lines BEHIND the cutting plane

9. Broken Out Section • Only a portion of the view is sectioned • A jagged break line is used to divide the sectioned and unsectioned portion of the drawing

10. Revolved Section • A cross section of the part is revolved 90° and superimposed on the drawing • A jagged break line may be used to divide the revolved section from the rest of the drawing

11. Revolved Section Caveats • Superimposition of Rev-Sec requires Removal of All ORIGINAL Lines Underneath the Section • Retain the TRUE-SHAPE of the Rev-Sec Regardless of the Line-Direction in the Visible-View

12. Removed Section • Similar to the revolved section except that the sectioned drawing is not superimposed on the drawing but placed adjacent to it • The view and the cutting plane are labeled (Sec. A-A) • The removed section may be drawn at a different scale • Very Useful for Detailing Small Parts or Features

13. Intersections - Windows • The Offset of the intersection from the Visible Lines is SMALL or Negligible • Can DisRegard the True Projection and Align to Vis-Lines • The Larger Intersection Does Have a Substantial Offset From the Visible Lines • Use the True-Projection to position the intersection

14. Intersections - PortHoles • The Offset of the intersection from the Visible Lines is SMALL or Negligible • Can DisRegard the True Projection and Align to Vis-Lines • Larger Intersections • For the Smaller Hole Use Tube OD (R1) and ID (r1) Arc at Depth Found by True Projection • For Hole K, rk = r1, SemiEllipses of Intersection appear asStraight-Lines

15. Special Sections • There are special rules (conventions) that are followed to make some parts more understandable • Some features are rotated to their TRUE RADIAL position in sectioned views • The object is difficult to understand using standard multiview drawings where hidden lines are used to represent internal features

16. Special Sections cont • Many Times If a part is sectioned as it would actually appear if cut, the details of Features such as ribs and holes may not be clear • Since the goal is to make the drawing easy to interpret the drawing is modified by the following std conventions • The cutting plane shows that the features are revolved to their true radial position • Hidden features are not shown • The sectioned drawing produced is a DISTORTED, but CLEARER, picture of the object • The section drawing appears as a full section • The arrows show the directionof the view

17. Special Sections cont • Ribs/Webs are not sectioned when the cutting plane passes through them lengthwise • Ribs are sectioned if the cutting plane passes through them at other orientations

18. SpecialSectionscont • The side view is replaced by a full section view • The cutting plane shown in the Front view shows the direction of the line of sight • The holes and ribs have been revolved to their true radial position • The ribs are not sectioned in this orientation • The section lines are all drawn at the same angle since the object is one solid part

19. Conventional Breaks • Use Conventional Breaks to Shorten an Elongated Object • “Jagged” Lines are used to Break Non-Circular Cross-section Objects • “S” Breaks are Preferred for Cylindrical Objects

20. Demo – Pipe Intersection • Let’s make a Cross Section for a Drilled, Thick-Walled Pipe

21. Final Result

22. All Done for Today Blue PrintCrossSec Circa 1862

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

24. Intersect Demo

25. Intersect Demo cont

26. Hatch Procedure-1

27. Hatch Procedure-2 • Hatch DiaLog Box 4

28. Hatch Procedure-3 • Pick Hatch Areas by Clicking ONCE ANYwhere within the Region

29. Hatch Procedure-4

30. Hatch Procedure-5 • All Done