Engineering Drawing: Chapter 04 orthographic writing

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Engineering Drawing: Chapter 04 orthographic writing

  1. 1. Chapter 4 Orthographic Writing
  2. 2. Contents Suggestions on a view selection Orthographic writing Primary auxiliary view Alignment of views (Projection systems) Basic dimensioning Overall steps Additional examples on a view selection
  3. 3. Orthographic writing Contents
  4. 4. Overall steps 1. Select the necessary views 2. Layout the selected views on a drawing sheet. 3. Complete each selected views. 4. Complete the dimensions and notes. 45 152 152 64 25~40 Front Top Choose a drawing scale (say 1:1) Front Top y y x x x x y y z
  5. 5. View selection procedures 1. Orient the object to the best position relative to a glass box. 2. Select the front view . 3. Select adjacent views .
  6. 6. Suggestions : Orient the object 1. The object should be placed in its natural position . NO ! 2. The orthographic views should represent the true size and true shape of an object (as much as possible). GOOD
  7. 7. Suggestions : Select the front view 1. The longest dimension of an object should be presented as a width (in a front view). Inappropriate First choice Good Second choice Use more space
  8. 8. Inappropriate 2. The adjacent views project from the selected front view should be appeared in a natural position . Suggestions : Select the front view
  9. 9. 3. It has the fewest number of hidden lines. Good Inappropriate Suggestions : Select the front view
  10. 10. Suggestions : Select an adjacent view Inappropriate Inappropriate 1. Choose the view that has the fewest number of hidden lines.
  11. 11. 2. Choose the minimum number of views that can represent the major features of the object. Necessary Necessary Hole’s information is placed on a separated view. Suggestions : Select an adjacent view All information is placed on a single view .
  12. 12. 3. Choose the views that are suitable to a drawing sheet. Good Suggestions : Select an adjacent view Poor Not enough space for dimensioning. Good Choose another adjacent view. Change orientation of the selected views.
  13. 13. Summary View selection has 3 steps In practice, drafter should consider all recommendations simultaneously before start to draw. Orient the object Select front view Select adjacent view
  14. 14. Additional examples on a view selection Contents
  15. 15. Notes In a usual case, three views orthographic drawing is selected to describes an object’s information. However, a necessary view may be less or more than three views. Later chapter
  16. 16. Object that requires only one -view Flat (thin) part having a uniform thickness such as a gasket, sheet metal etc. Adjacent views provide only a part’s thickness ! 1 Thick Cylindrical-shaped part. Example
  17. 17. Repeat ! Infer from CL Object that requires only one -view Example Example Flat (thin) part having a uniform thickness such as a gasket, sheet metal etc. Cylindrical-shaped part.
  18. 18. Identical adjacent view exists. Repeat ! Object that requires only two -view The 3 rd view has no significant contours of the object. (provides no additional information) Example
  19. 19. Object that requires only two -view Identical view exists. Example 1 The 3 rd view has no significant contours of the object. (provides no additional information)
  20. 20. Object that requires only two -view Identical view exists. Example 2 The 3 rd view has no significant contours of the object. (provides no additional information)
  21. 21. Class activity : View selection 2 1 3 4 6 5 Select a necessary view ?
  22. 22. Class activity : View selection Select a necessary view ? 2 1 3 4 6 5
  23. 23. Class activity : View selection 2 1 3 4 6 5 Select a necessary view ?
  24. 24. Alignment of views Contents
  25. 25. Projection systems 1. First angle system 2. Third angle system First quadrant Third quadrant - European countries - ISO standard - Canada, USA, Japan, Thailand Transparent planes Opaque planes
  26. 26. 1 st angle system (Opaque planes) 3 rd angle system (transparent planes/glass box) Orthographic views
  27. 27. Folding line Folding line Folding line Folding line   1 st angle system 3 rd angle system Orthographic views
  28. 28. 1 st angle system 3 rd angle system Front View Front View Right Side View Right Side View Top View Top View Views arrangement
  29. 29. Projection symbols 1 st angle system 3 rd angle system d 1.7 d 2.2 d
  30. 30. Basic dimensioning Contents
  31. 31. 1. Extension lines 2. Dimension lines 3. Leader lines 4. Dimension numbers 5. Local notes Dimensioning components 10 27 43 10 Drill, 2 Holes R16 17
  32. 32. Primary auxiliary view Contents
  33. 33. Necessity Auxiliary view is needed when it is desirable to show the true size and shape of a surface that is not parallel to one of the principal planes of projection. True size can not be observed from these principal views.
  34. 34. Use of auxiliary view In practice, an auxiliary view is usually a partial view showing only the desired information. Example Complete view Partial view d d d d
  35. 35. Types of an auxiliary view Primary auxiliary views may be classified into 3 types by their relative to the principal views. 1. Adjacent to front view 2. Adjacent to top view 3. Adjacent to side view
  36. 36. Width & Height & True length of edge view Width & Depth Height & Depth Auxiliary view adjacent to front view Glass box and revolution View arrangement True size of an inclined plane
  37. 37. Example 1 Do you remember? Depth dimension of the auxiliary view can be read from top view or side view. Auxiliary plane
  38. 38. Hidden lines of the holes are omitted for clarity. Start Reference line A C D B Prefer distance A B C D Example 2
  39. 39. Width & Height Height & Depth Auxiliary view adjacent to top view Glass box and revolution Width & Depth & True length of edge view True size of an inclined plane View arrangement
  40. 40. Width & Height Auxiliary view adjacent to side view Glass box and revolution Width & Depth True size of an inclined plane View arrangement Height & Depth & True length of edge view
  41. 41. Example Reference line Start Prefer distance A B C A B C

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