Drawing

1. EnginEEring Drawing
By: Engr. Rauf Ahmad

2. Chapter 1
Introduction
LEC 01, Introduction 2

3. Contents
Drawing standards
Engineering drawing
Drawing sheet
Scale
Lettering
Line types
LEC 01, Introduction 3

4. The things you need
LEC 01, Introduction 4

5. Items required for drawing Items required for drawing
Drawing board (Available in Drawing Halls)
Drawing sheet (Half Scholar Sheet)
Mini-drafter/drafting machine/T- square(2ft or 3ft)
Instrument box containing compass, divider, etc.
Scales(6in. or 12in.)
Set-Squares & Protractor(30cm)
French curves(not required)
Drawing pencils(A lots of them)
Eraser(smooth)
Drawing clip/pin/adhesive tape
Sharpener
Duster LEC 01, Introduction 5

6. Standard sizes of drawing sheets as per BIS
A2 sizeLEC 01, Introduction 6

7. Instrument Drawing
Drawing Pencils
High-quality drawing pencils should be used in technical drawing, never ordinary writing pencils.
Many makes of mechanical pencils are available together with refill leads in all grades. Choose a
mechanical pencil that feels comfortable in your hand.
LEC 01, Introduction 7

8. Drawing Pencils
Wooden pencils – are graded and designated by numbers and letters
Mechanical clutch pencils – Not allowed
• 7B, 6B, 5B, 4B, 3B, 2B, B - in decreasing order of softness and
blackness
• HB to F – Medium grade
• H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H – increasing order of
hardness.
Drawings are done using 2HLEC 01, Introduction 8

9. ades and designation of wooden peLEC 01, Introduction 9

10. Pencil drawing –
In finished drawing, all lines (except construction lines-
used to construct the drawing) should be dense, clean
and uniform.
Construction line should be drawn very thin and should
be hardly visible in the finished drawing ( they should
not be erased).
LEC 01, Introduction 10

11. Line types
LEC 01, Introduction 11

12. Line types….CONTD
LEC 01, Introduction 12

13. Engineering
Drawing
The words of the language, as they are written or spoken, do not seem to play any role in my
mechanism of thought. The psychical entities which seem to serve as elements in thought are
certain signs and more or less clear images which can be “voluntarily” reproduced and
combined--this combinatory play seems to be the essential feature in productive thought before
there is any connection with logical construction in words or other kinds of signs which are
communicated to others
--Albert Einstein
Contents

14. 1. Try to write a description of
this object.
2. Test your written description
by having someone attempt
to make a sketch or visualize
from your description.
Effectiveness of Graphic Language
The word language is inadequate for describing the sizesize,
shapeshape and featuresfeatures completely as well as concisely.
You can easily understand that …
LEC 01, Introduction 14

15. Graphic Language in
Engineering Drawing
“Engineering drawing” or “blueprint” uses llinesines to
represent the featuresfeatures of an object.
Features of an object are surfacesurface (include planeplane) and
edgeedge.
Surface
Edge
LEC 01, Introduction 15

16. A drawing can be created in 3 ways
Ways to Create an
Engineering Drawing
1. Freehand sketch
2. Using typical drawing instruments
3. Using a computer
LEC 01, Introduction 16

17. Example
Create a Drawing : Freehand sketch
The lines are drawn using only pencil and erasers on a
blank or grid paper.
Pictorial sketch Orthographic sketch
LEC 01, Introduction 17

18. Example
Create a Drawing : Using instruments
Drawing instruments are used to
draw straight lines, circles, and
curves conciselyconcisely and accuratelyaccurately.
Drawings are usually made to scalemade to scale.
LEC 01, Introduction 18

19. Example
Create a Drawing : Using a computer
Computer aided drafting (CAD) software is used.
2D drawing Solid modeling
LEC 01, Introduction 19

20. Elements of a Drawing
A clear and precise engineering drawing requires both
graphicsgraphics and wordword languages.
Graphics language
Describe a shape (mainly).
Word language
Describe an exact size,
location and specification
of the object.
LEC 01, Introduction 20

21. Text on drawings : Example
General
notes Title
block
Dimensions
&
Notes
LEC 01, Introduction 21

22. Knowledge and Skills Require
Graphics
language
Word
language
Dimensions & Notes
VisualizationVisualization is the ability to mentally picture things that do not exists.
VisualizationUsing line types
Geometric
construction
Projection
method
Engineering Drawing
Contents
LEC 01, Introduction 22

23. Drawing Standard
Drawing sheet Scale Lettering Line types Contents

24. Definition and Necessity
Drawing standards are set of rulesset of rules that govern how
technical drawings are represented.
Drawing standards are used so that drawings conveyconvey
the same meaningthe same meaning to everyone who reads them.
LEC 01, Introduction 24

25. ISO International Standards Organization
Standard Code
ANSI American National Standard InstituteUSA
JIS Japanese Industrial StandardJapan
BS British StandardUK
AS Australian StandardAustralia
Deutsches Institut für NormungDINGermany
Country Code Full name
มอก./TISสำำนักงำนมำตรฐำนผลิตภัณฑ์อุตสำหThailand
LEC 01, Introduction 25

26. Examples of TIS Standard
ก. 210 2520 วิธีเขียนแบบทั่วไป : ทำงเครื่องกล
ก. 440 ล.1 2541 กำรเขียนแบบก่อสร้ำงเล่ม 1 ทั่วไป
มอก. 446 ล.4 2532 ข้อแนะนำำสำำหรับกำร
เขียนแผนภำพวงจรไฟฟ้ำก. 1473 2540 กำรเขียนแบบเทคนิค กำรติดตั้ง
สัญลักษณ์สำำหรับระบบท่อของเหลว
ระบบทำำควำมร้อน กำรระบำยอำกำศ
และระบบท่ออำกำศ
Code number Contents
ที่มำ : http://library.tisi.go.th/data/lib_resources/pdf/catalog-online49/tis/02_ICS.pdf
LEC 01, Introduction 26

27. JIS Z 8311 Sizes and Format of DrawingsSizes and Format of Drawings
JIS Z 8312 Line ConventionsLine Conventions
JIS Z 8313 LetteringLettering
JIS Z 8314 ScalesScales
JIS Z 8315 Projection methods
JIS Z 8316 Presentation of Views and Sections
JIS Z 8317 Dimensioning
Code number Contents
Examples of JIS Standard
LEC 01, Introduction 27

28. Drawing Standard
Drawing Sheet
Drawing standard Contents

29. Drawing Sheet : Standard size
Trimmed paper of
a size A0 ~ A4.
Standard sheet size
(JIS)
A4 210 x 297
A3 297 x 420
A2 420 x 594
A1 594 x 841
A0 841 x 1189
A4
A3
A2
A1
A0
(Dimensions in millimeters)
LEC 01, Introduction 29

30. Drawing space
Drawing
space
Title block
d
d
c
c
cBorder
lines
1. Type X (A0~A4)
2. Type Y (A4 only)
Title block
Sheet size c (min) d (min)
A4 10 25
A3 10 25
A2 10 25
A1 20 25
A0 20 25
Drawing Sheet : Orientation & Margin
LEC 01, Introduction 30

31. Drawing Standard
Drawing Scale
Drawing standard Contents

32. Drawing Scales : Definition
Drawing Actual
Length, size
:
ScaleScale is a ratio between the linear dimension of a
drawn representation of an object and the actual object.
1 2
LEC 01, Introduction 32

33. Designation of a scale consists of the word “SCALE”
followed by the indication of its ratio, as follows
SCALE 1:1 for full size
SCALE X:1 (X > 1) for an enlargementenlargement scales
SCALE 1:X (X > 1) for a reductionreduction scales
Drawing Scales : Designation
Drawing scale is commonly found in a title block.
LEC 01, Introduction 33

34. Dimension numbersDimension numbers shown in the drawing represent
the “true size” of an object and they are independent of
the drawing scale used.
Drawing Scales : Notes
LEC 01, Introduction 34

35. Standard reducing scales are
1:2, 1:5, 1:10, 1:20, 1:50, 1:100
Drawing Scales : Standard scale
Standard enlarging scales are
2:1, 5:1, 10:1, 20:1, 50:1, 100:1
LEC 01, Introduction 35

36. Drawing Standard
Lettering
Drawing standard Contents

37. - Size (or text height)
- line thickness
- Shape
- Space between letters
- Space between words
Recommendation
LegibilityLegibility
UniformityUniformity
Text’s style on the drawing
must have the following
2 properties
Examples
GOOD
Not uniform in style.
Not uniform in height.
Not uniformly vertical.
Not uniform in
thickness of stroke.
Inappropriate space
between letters
LEC 01, Introduction 37

38. Style (this course)
Gothic vertical style.
Begin the sentence, phrase or word with a capital letter.
Text height 2~3 mm.
Space between lines of text is about of text height.
Height of the lower-case letter is about 2/3 of that of a
capital letter.
LEC 01, Introduction 38

39. Basic Strokes
Straight Slanted CurvedHorizontal
1 1 2
3
“I” letter “A” letter
1
2
3
4 5
6
“B” letter
Examples
LEC 01, Introduction 39

40. Suggested Strokes Sequence
Straight line
letters
Curved line
letters
&
Numerals
Upper-case Letters & Numerals
LEC 01, Introduction 40

41. Lower-case Letters
LEC 01, Introduction 41

42. I L T F
E H
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 42

43. V X W
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 43

44. N M K Z
Y A 4
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 44

45. O Q C G
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 45

46. D U P B
R J
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 46

47. 5 7
Stroke Sequence : Upper-case
1 2
Skip section
LEC 01, Introduction 47

48. 6
8 9
0S 3
Stroke Sequence : Upper-case
Skip section
LEC 01, Introduction 48

49. l i
Stroke Sequence : Lower-case
Skip section
LEC 01, Introduction 49

50. v w x k
z
Stroke Sequence : Lower-case
Skip section
LEC 01, Introduction 50

51. j y f
r
t
Stroke Sequence : Lower-case
Skip section
LEC 01, Introduction 51

52. c o a b
d p q e
Stroke Sequence : Lower-case
Skip section
LEC 01, Introduction 52

53. g n m h
u s
Stroke Sequence : Lower-case
Skip section
LEC 01, Introduction 53

54. DRAWING
Word Composition
Non-uniform
spacing
Uniform
spacing
DR A WING
Space between the letters depends on the adjacent
contour of the letters.
Word having non-uniform spacing is more readable.
LEC 01, Introduction 54

55. Word Composition
Contour
DRAWING
Contour can be denoted as “straight”, “slant” and “curve”.
Adjacent contour can be
1. straight-straight : II, IN, IM, IP etc.
2. straight-curve (or curve-straight) : IO, QR etc.
3. straight-slant (or slant-straight) : IV, IW etc.
4. curve-curve : OO, OG etc.
5. slant-curve (or curve-slant) : VO, WG, VC etc.
6. slant-slant : VW, VX etc.
Spacing
LEC 01, Introduction 55

56. Leave the space between words equal to the space
requires for writing a letter “O”.
Example
Sentence Composition
ALL DIMENSIONS ARE IN
MILLIMETERS
O O O
O UNLESS
OTHERWISE SPECIFIED.O
LEC 01, Introduction 56

57. Drawing Standard
Line Types
Drawing standard Contents

58. Basic Line Types &
Name according to application
Continuous
Dash
Chain
Style
Thickness Thick Thin 1. Dimension line
2. Extension line
3. Leader line
Center line
Hidden line
Visible line
represent features that can be seen in the current view.
represent features that can not be seen in the current view.
represents symmetry, path of motion, centers of circles,
axis of axisymmetrical parts
indicate the sizes and location of features.
1. Visible line
3. Hidden line
4. Center line
2. Dimension line
Extension line
Leader line
LEC 01, Introduction 58

59. Example
Contents
LEC 01, Introduction 59