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1. Section Views

2. Sectioning image
NO information about
Cutting the apple with knife
apple inside
After cutting we
get information
about in side

3. Sectioning image
Information
about color
NO information about Cutting the watermelon by knife
inside Watermelon
Information
about taste
Information
about seeds

4. PURPOSES OF SECTION VIEWS
Clarify the views by
 reducing or eliminating the hidden lines.
 revealing the cross sectional’s shape.
 Describing the material
Facilitate the dimensioning.

5. EXAMPLE : Advantage of using a section view.

6. CUTTING PLANE
Cutting plane is a plane that imaginarily cuts
the object to reveal the internal features.
Cutting
plane Cutting plane line
Section lines

7. CUTTING PLANE LINE
Cutting plane line is an edge view of the cutting plane.
Indicate the path
of cutting plane.

8. CUTTING PLANE LINESTYLES
Thick line
ANSI
Viewing
standard
direction
Thick line
Viewing
direction
JIS & ISO Thin line
standard
Viewing
direction

9. SECTION LINING
Section lines or cross-hatch lines are used to
indicate the surfaces that are cut by the cutting
plane.
Section
lines
Drawn with 4H pencil.

10. SECTION LINES SYMBOLS
The section lines are different for each of
material’s type.
For practical purpose, the cast iron symbol is used
most often for any materials.
Cast iron, Steel Concrete Sand Wood
Malleable iron

11. SECTION LINING PRACTICE
The spaces between lines may vary from 1.5 mm
for small sections to 3 mm for large sections.
COMMON MISTAKE

12. SECTION LINING PRACTICE
It should not be drawn parallel or perpendicular to
contour of the view.
COMMON MISTAKE

13. Kinds of Sections

14. KIND OF SECTIONS
1. Full section
2. Offset section
3. Half section
4. Broken-out section
5. Revolved section (aligned section)
6. Removed section (detailed section)

15. FULL SECTION VIEW
The view is made by passing the straight cutting plane
completely through the part.

16. OFFSET SECTION VIEW
The view is made by passing the bended cutting plane
completely through the part.
Do not show the edge views
of the cutting plane.

17. TREATMENT OF HIDDEN LINES
Hidden lines are normally omitted from section
views.

18. HALF SECTION VIEW
The view is made by passing the cutting plane halfway
through an object and remove a quarter of it.

19. HALF SECTION VIEW
A center line is used to separate the sectioned half from the
unsectioned half of the view.
Hidden line is omitted in unsection half of the view.

20. BROKEN-OUT SECTION VIEW
The view is made by passing the cutting plane normal to the
viewing direction and removing the portion of an object in
front of it.

21. BROKEN-OUT SECTION VIEW
A break line is used to separate the
sectioned portion from the
unsectioned portion of the view.
Break line is a thin continuous line
(4H) and is drawn freehand.
There is no cutting plane line.

22. EXAMPLE : Comparison among several section techniques

23. REVOLVED SECTION VIEW
Revolved sections show cross-sectional
features of a part.
No need for additional orthographic views.
This section is especially helpful when a
cross-section varies.

24. REVOLVED SECTION VIEW
Basic concept

25. REVOLVED SECTION VIEW
Basic concept

26. REVOLVED SECTION VIEW
Steps in construction
Given
Edge view of
cross-section
Step 1
a. Assign position of cutting plane.
b. Draw axis of rotation in front view.

27. REVOLVED SECTION VIEW
Steps in construction
Given
Step 2
a. Transfer the depth dimension to
the front view.

28. REVOLVED SECTION VIEW
Steps in construction
Given
Step 3
a. Draw the revolved section.
b. Add section lines.

29. REVOLVED SECTION VIEW
Steps in construction
Given
FINAL PICTURE

30. REVOLVED SECTION VIEW
Placement of revolved section
1. Superimposed to orthographic view.
2. Break from orthographic view.
Break Superimposed

31. REMOVED SECTION VIEW
6. Removed section
Removed section is revolved section.
Section view is shown outside the view.
Used where space does not enough for
revolved section
Can be located elsewhere on a drawing
with properly labeled

32. REMOVED SECTION VIEW
Example : Revolved vs. removed sections.
Revolved section Removed section

33. REMOVED SECTION VIEW
Example : Situation that removed section is preferred.
Poor Preferred
Too messy !!

34. REMOVED SECTION VIEW
Example : Multiple removed section views
A B
B
A
SECTION B – B
SECTION A – A

35. Section view
representation of
rib, web, spoke and lug

36. TERMINOLOGY
Rib and Web are thin, flat feature of an object that acts
as a structural support.
Web
Rib Rib

37. TERMINOLOGY
Spoke is the rod radiating from the hub to the rim of a
wheel.
Hub
Hub
Spoke Rim
Spoke
Rim

38. TERMINOLOGY
Lug is an ear which is built as portion of an object for
attachment.

39. CONVENTIONAL PRACTICE
Omit the section lines on the section view of
 Rib, Web and Lug, if the cutting plane is
passed flatwise through.
 Spoke, if the cutting plane is passed longwise
through.

40. EXAMPLE : RIB
Normal multiview drawing
Normal section view
Section view drawing with
convention

41. EXAMPLE : WEB : flatwise cut
Normal multiview drawing
Normal section view
Section view drawing with
convention

42. EXAMPLE : WEB : crosswise cut

43. EXAMPLE : WEB : multiple section view

44. EXAMPLE : SPOKE
Misleading impression

45. EXAMPLE : LUG

46. Aligned Section

47. DEFINITION
Aligned section is a section view that is drawn
by imaginary rotating the object’s features
appeared in a principal view about symmetry
axis

48. Example : HOLE
Gives the impression that this holes
are at unsymmetrical position.

49. Example : HOLE

50. Example : RIB

51. Example : Aligned section of lug

52. Conventional Break

53. CONVENTIONAL PRACTICE
For long objects that have to draw in a small scale to
fit them on the paper, it is recommended to remove
its long portion (which contains no important
information) and draw the break lines at the broken
ends.

54. Example
SCALE 1:1
2:1

55. STANDARD BREAK LINES
Wood
Rectangular
cross section
Metal
Cylindrical
cross section
Tubular
cross section

56. TO DRAW CYLINDRICAL BREAK
30o
R
30o
R/3 R/3

57. TO DIMENSION A BROKEN PART
f16
Typical method 800
f16
800
Use not to scale dimensions

58. Dimensioning

59. ENGINEERING DESIGN
PROCESS RESULT
Design
a part Sketches
of ideas
Multiview
Create Shape
drawings
Drawing
1. Size, Location
Dimensioning
2. Non-graphic information
Manufacture

60. DEFINITION
Dimensioning is the process of specifying part’ s information by using of
figures, symbols and notes.
This information are such as:
1. Sizes and locations of features
2. Material’s type This course
3. Number required
4. Kind of surface finish
5. Manufacturing process
6. Size and geometric tolerances

61. DIMENSIONING SYSTEM
1. Metric system : ISO and JIS standards This
course
Examples 32, 32.5, 32.55, 0.5 (not .5) etc.
2. Decimal-inch system
Examples 0.25 (not .25), 5.375 etc.
3. Fractional-inch system
1 , 3
Examples 5 etc.
4 8

62. Dimensioning
Components

63. DIMENSIONING COMPONENTS
Extension lines
Dimension lines Drawn with
(with arrowheads) 4H pencil
Leader lines
Dimension figures
Notes : Lettered with
- local note 2H pencil.
- general note

64. EXTENSION LINES
indicate the location on the object’s features that are dimensioned.

65. DIMENSION LINES
indicate the direction and extent of a dimension, and inscribe dimension figures.
10 27
13
43

66. LEADER LINES
indicate details of the feature with a local note.
10 27 10 Drill, 2 Holes
R16
13
43

67. Recommended
Practices

68. EXTENSION LINES
Leave a visible gap (≈ 1 mm) from a view and start drawing an extension line.
Extend the lines beyond the (last) dimension line 1-2 mm.
COMMON MISTAKE
Visible gap

69. EXTENSION LINES
Do not break the lines as they cross object lines.
COMMON MISTAKE
Continuous

70. DIMENSION LINES
Dimension lines should not be spaced too close
to each other and to the view.
Leave a space at least
2 times of a letter height.
16
34
11
35
Leave a space at least
1 time of a letter height.

71. DIMENSION FIGURES
The height of figures is suggested to be 2.5~3 mm.
Place the numbers at about 1 mm above dimension
line and between extension lines.
COMMON MISTAKE
34
11
34
11

72. DIMENSION FIGURES
When there is not enough space for figure or
arrows, put it outside either of the extension lines.
Not enough space Not enough space
for figures for arrows
16.25 1
16.25 1 1
or

73. DIMENSION FIGURES : UNITS
The JIS and ISO standards adopt the unit of
Length dimension in millimeters without
specifying a unit symbol “mm”.
Angular dimension in degree with a symbol “o”
place behind the figures (and if necessary
minutes and seconds may be used together).

74. DIMENSION FIGURES : ORIENTATION
1. Aligned method
The dimension figures are placed so that they are readable from the
bottom and right side of the drawing.
2. Unidirectional method
The dimension figures are placed so that they can be read from the
bottom of the drawing.
Do not use both system on the same drawing or on the same series of
drawing (JIS Z8317)

75. EXAMPLE : Dimension of length using aligned method.
30
30
30
30

76. EXAMPLE : Dimension of length using unidirectional method.
30
30 30
30 30
30 30
30

77. EXAMPLE : Dimension of angle using aligned method.
45o
45o
45o
45o

78. EXAMPLE : Dimension of angle using unidirectional method.
45o
45o 45o
45o 45o
45o 45o
45o

79. LOCAL NOTES
Place the notes near to the feature which they
apply, and should be placed outside the view.
Always read horizontally.
COMMON MISTAKE
10 Drill 10 Drill
10 Drill
≈ 10mm
Too far

80. THE BASIC CONCEPT
Dimensioning is accomplished by adding size and location information
necessary to manufacture
the object.
This information have to be
Clear
Complete
Facilitate the
- manufacturing method
- measurement method

81. EXAMPLE
L L
Designed
part
L
S
L
S
To manufacture this part S
we need to know…
1. Width, depth and S
thickness of the part.
2. Diameter and depth
of the hole.
“S” denotes size dimension.
3. Location of the holes. “L” denotes location dimension.

82. ANGLE
To dimension an angle use circular dimension
line having the center at the vertex of the angle.
COMMON MISTAKE

83. ARC
Arcs are dimensioned by giving the radius, in the
views in which their true shapes appear.
The letter “R” is always lettered before the figures
to emphasize that this dimension is radius of an
arc.
or

84. ARC
The dimension figure and the arrowhead should
be inside the arc, where there is sufficient space.
Sufficient space Sufficient space Insufficient space
for both. for arrowhead only. for both.
Move figure outside Move both figure
and arrow outside
R 62.5
R 6.5
R 58.5

85. ARC
Leader line must be radial and inclined with
an angle between 30 ~ 60 degs to the horizontal.
COMMON MISTAKE
R62.5 R62.5 R62.5
R62.5
R62.5 R62.5

86. ARC
Use the foreshortened radial dimension line,
when arc’ s center locates outside the sheet or
interfere with other views.
Method 1
2
Drawing sheet

87. FILLETS AND ROUNDS
Give the radius of a typical fillet only by using a
local note.
If all fillets and rounds are uniform in size,
dimension may be omitted, but it is necessary to
add the note “ All fillets and round are Rxx. ”
R6.5 R12
NOTE:
NOTE: All fillets and round are R6.5
All fillets and round are R6.5 unless otherwise specified.
Drawing sheet

88. CURVE
The curve constructed from two or more arcs,
requires the dimensions of radii and center’s
location.
COMMON MISTAKE
Tangent point

89. CYLINDER
Size dimensions are diameter and length.
Location dimension must be located from its
center lines and should be given in circular view.
Measurement
method

90. CYLINDER
Diameter should be given in a longitudinal view with the symbol “f ” placed
before the figures.
f 100
f 70

91. HOLES
Size dimensions are diameter and depth.
Location dimension must be located from its
center lines and should be given in circular view.
Measurement
method

92. HOLES : SMALL SIZE
Use leader line and local note to specify diameter
and hole’s depth in the circular view.
1) Through thickness hole
f xx f xx Thru. xx Drill. xx Drill, Thru.
or or or

93. HOLES : SMALL SIZE
Use leader line and local note to specify diameter
and hole’s depth in the circular view.
2) Blind hole
f xx, yy Deep xx Drill, yy Deep
or
Hole’s
depth

94. HOLES : LARGE SIZE
Use extension and Use diametral Use leader line
dimension lines dimension line and note
f xx

95. HOLES
COMMON MISTAKE
f xx f xx
f xx Rxx
f xx
f xx

96. CHAMFER
Use leader line and note to indicate linear
distance and angle of the chamfer.
S q
S
For a 45o chamfer
or
CS S S

97. ROUNDED-END SHAPES
Dimensioned according to the manufacturing
method used.
f 12 Center to Center Distance
R12
21
5

98. ROUNDED-END SHAPES
Dimensioned according to the manufacturing
method used.
R12
12
21
Center to Center Distance
5

99. ROUNDED-END SHAPES
Dimensioned according to the manufacturing
method used.
R12
12
16 21

100. ROUNDED-END SHAPES
Dimensioned according to the manufacturing
method used.
R12
12
27
Tool cutting distance

101. ROUNDED-END SHAPES
Dimensioned according to the standard sizes of
another part to be assembled or manufacturing
method used.
Key
(standard part)
25

102. ROUNDED-END SHAPES
Dimensioned according to the standard sizes of
another part to be assembled or manufacturing
method used.
20

103. Placement of
Dimensions

104. RECOMMENDED PRACTICE
1. Extension lines, leader lines should not cross
dimension lines.
POOR GOOD

105. RECOMMENDED PRACTICE
2. Extension lines should be drawn from the nearest
points to be dimensioned.
POOR GOOD

106. RECOMMENDED PRACTICE
3. Extension lines of internal feature can cross visible
lines without leaving a gap at the intersection point.
WRONG CORRECT

107. RECOMMENDED PRACTICE
4. Do not use object line, center line, and dimension
line as an extension lines.
POOR GOOD

108. RECOMMENDED PRACTICE
5. Avoid dimensioning hidden lines.
POOR GOOD

109. RECOMMENDED PRACTICE
6. Place dimensions outside the view, unless
placing them inside improve the clarity.
POOR GOOD

110. RECOMMENDED PRACTICE
6. Place dimensions outside the view, unless
placing them inside improve the clarity.
JUST OK !!! BETTER

111. RECOMMENDED PRACTICE
7. Apply the dimension to the view that clearly show
the shape or features of an object.
POOR GOOD

112. RECOMMENDED PRACTICE
8. Dimension lines should be lined up and grouped
together as much as possible.
POOR GOOD

113. RECOMMENDED PRACTICE
9. Do not repeat a dimension.
POOR GOOD