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Chapter 1 engineering drawing

THAI NGUYEN UNIVERSITY OF TECHNOLOGY
Mechanical Faculty
Mechanical Engineering Division

PART II

ENGINEERING
DRAWING


Engineering drawing
Drawing standards
Drawing sheet
Scale
Lettering
Line types


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


Effectiveness of Graphic Language
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.
3. And…try again with this object

You can easily understand that …

The word language is inadequate for describing the size,
shape and features completely as well as concisely.


Graphic Language in
Engineering Drawing
“Engineering drawing” or “blueprint” uses lines to
represent the features of an object.
Features of an object are surface (include plane) and
edge.
Surface
Edge


Ways to Create an Engineering Drawing
1. Freehand sketch


Ways to Create an Engineering Drawing


1. Freehand sketch
2. Using typical drawing instruments
3. Using a computer

The lines are drawn using only
pencil and erasers on a blank or
grid paper.

Drawing instruments are used to draw
straight

lines,

circles,

and

curves

concisely and accurately. Drawings are
usually made to scale.


*Using a computer
Computer aided drafting (CAD) software is used.

2D drawing

Solid modeling


Elements of a Drawing
A clear and precise engineering drawing requires both

graphics and word languages.

Graphics language
Describe a shape (mainly).

Word language
Describe an exact size,
location and specification
of the object.


Knowledge and Skills Require
Engineering Drawing
Word
language

Graphics
language
Geometric
construction
Using line types

Projection
method

Dimensions & Notes

Visualization

Visualization is the ability to mentally picture things that do not exists.
Contents


Drawing Standards

Drawing sheet

Scale

Lettering

Line types

Contents


Definition and Necessity
Drawing standards are set of rules that govern how
technical drawings are represented.
Drawing standards are used so that drawings convey
the same meaning to everyone who reads them, and
do not make unmistakeable. (the success or failure of
a structure depends on the clarity and details of the

drawing)


Standard Code
Country

Thailand
USA

Code

Full name

/TIS
ANSI

American National Standard Institute

Japan

JIS

Japanese Industrial Standard

UK

BS

British Standard

Australia

AS

Australian Standard

Germany

DIN

Deutsches Institut für Normung

ISO

International Standards Organization

TCVN

Tiêu Chuẩn Việt Nam


Examples of JIS Standard
Contents

Code number
JIS Z 8311

Sizes and Format of Drawings

JIS Z 8314

Scales

JIS Z 8312

Line Conventions

JIS Z 8313

Lettering

JIS Z 8315

Projection methods

JIS Z 8316

Presentation of Views and Sections

JIS Z 8317

Dimensioning


Drawing Sheet : Standard size
Trimmed paper of
a size A0 ~ A4.

Standard sheet size
(JIS)
A4
A3
A2
A1
A0

210 x 297
297 x 420
420 x 594
594 x 841
841 x 1189

(Dimensions in millimeters)

A4
A3
A2

A1

A0


Drawing Sheet : Orientation & Margin
c

1. Type X (A0~A4)
Sheet size
A4
Border d
lines

c

c

Drawing space

Title block
2. Type Y (A4 only)

d
Drawing
space

Title block

A3
A2
A1
A0

c (min) d (min)
10
25
(5)
(25/5)
10
25
10
25
20
25
20
25


A4
A3
A2

A4

A3

A3

A2

* Multi Drawings in paper.
* Do not “economize”

17/28


Drawing Scales : Definition
Length, size

Scale is a ratio between the linear dimension of a
drawn representation of an object and the actual object.

100

1

:

2
100

Drawing

Actual

Dimension numbers shown in the drawing represent the
“true size” of an object and they are independent of the
drawing scale used.


Drawing Scales
Designation of a scale consists of the word “Scale”

followed by the indication of its ratio, as follows
Scale 1:1
Scale X:1
Scale 1:X

for full size
(X > 1) for an enlargement scales
(X > 1) for a reduction scales

X= 2, 5, 10, 20, 50, 100…

Drawing scale is commonly found in a title block (10).
(1)
(4)

(2)

(3)

(5)

(6)

(9)

(7)
(10)
(8)

(11)


Drawing Standard
Lettering


Drawing Letters
Text’s style on the drawing
must have the following
2 properties

Examples
GOOD
Not uniform in style.

Legibility
- Shape

Not uniform in height.

- Space between letters
- Space between words

Uniformity
- Size (or text height)

- line thickness

Not uniformly vertical.
Not uniform in
thickness of stroke.
Inappropriate space
between letters


Basic Line Types &
Name according to application
Thickness
Style

Thick

Thin
Visible line

Continuous
Dash
Chain
1. Visible line

1. Dimension line
2. Extension line
3. Leader line
Hidden line
Center line

represent features that can be seen in the current view.

2. Dimension line
Extension line indicate the sizes and location of features.
Leader line
3. Hidden line

represent features that can not be seen in the current view.

4. Center line

represents symmetry, path of motion, centers of circles,
axis of axisymmetrical parts


60

1

A

7
6
9

5

3

2
A

1120

10

4

8


Drawing order…
1>6>7>5


Exercises:
1. Match objects (A,B) with target shapes (1-20)


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