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Engineering Graphics- Basics
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Overview of an Engineering Drawing
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GRAPHICS LANGUAGE
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Effectiveness of Graphics Language
1. Try to write a description of this object.
2. Test your written description by having
someone attempt to make a sketch from your
description.
You can easily understand that
The word languages are inadequate for describing
the size, shape and features completely as
well as concisely.
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DRAWINGS ( A Graphical Representation)
The Fact about If compared with Verbal or
Written Description, Drawings offer far better
idea about the Shape, Size Appearance of any
object or situation or location, that too in
quite a less time.
Hence it has become the Best Media of
Communication not only in Engineering but in
almost all Fields.
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Composition of Graphic Language
Graphic language in engineering application
use lines to represent the surfaces, edges and
contoursof objects.
The language is known as drawing or
drafting .
A drawing can be done using freehand,
instruments or computer methods.
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Freehand drawing The lines are sketched without
using instruments other than pencils and erasers.
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Instrument drawing Instruments are used to draw
straight lines, circles, and curves concisely
and accurately. Thus, the drawings are usually
made to scale.
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Computer drawing The drawings are usually made
by commercial software such as AutoCAD, solid
works etc.
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Engineering Drawing
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Elements of Engineering Drawing
Engineering drawing are made up of graphics
language and word language.
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Basic Knowledge for Drafting
Word language
Graphics language
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Drawing Standard
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Standards are set of rules that govern how
technicaldrawings are represented.
Drawing standards are used so that drawings
convey the same meaning to everyone who reads
them.
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Standard Code
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Drawing Sheet
A4
Trimmed paper of a size A0 A4.
A3
Standard sheet size (JIS) A4 210 x 297 A3
297 x 420 A2 420 x 594 A1 594 x 841 A0 841
x 1189
A2
A1
A0
(Dimensions in millimeters)
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Drawing Scales
Designation of a scale consists of the word
SCALE followed by the indication of its ratio,
as follow
SCALE 11 for full size SCALE X1 for
enlargement scales SCALE 1X for reduction
scales
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Basic Line Types
Name according to application
Types of Lines
Appearance
NOTE We will learn other types of line in later
chapters.
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Meaning of Lines
Visible lines represent features that can be
seen in the current view
Hidden lines represent features that can not be
seen in the current view
Center line represents symmetry, path of
motion, centers of
circles, axis of axisymmetrical parts
Dimension and Extension lines indicate the sizes
and location of features
on a drawing
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Example Line conventions in engineering drawing
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Traditional Drawing Tools
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DRAWING TOOLS
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DRAWING TOOLS
1. T-Square
2. Triangles
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DRAWING TOOLS
2H or HB for thick line
4H for thin line
3. Adhesive Tape
4. Pencils
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DRAWING TOOLS
5. Sandpaper
6. Compass
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DRAWING TOOLS
7. Pencil Eraser
8. Erasing Shield
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DRAWING TOOLS
9. Circle Template
10. Tissue paper
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DRAWING TOOLS
11. Sharpener
12. Clean paper
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Lettering
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Text on Drawings
Text on engineering drawing is used
To communicate nongraphic information.
As a substitute for graphic information, in those
instance where text can communicate the needed
information more clearly and quickly.
Thus, it must be written with
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Example
Placement of the text on drawing
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Lettering Standard
ANSI Standard
This course
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Stroke Sequence
T
F
L
I
E
H
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Stroke Sequence
V
X
W
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Stroke Sequence
Z
M
K
N
4
Y
A
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Stroke Sequence
G
Q
C
O
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Stroke Sequence
U
P
B
D
R
J
1
2
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Stroke Sequence
7
5
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Stroke Sequence
6
0
3
S
8
9
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Stroke Sequence
i
l
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Stroke Sequence
w
x
k
v
z
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Stroke Sequence
y
f
t
j
r
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Stroke Sequence
o
a
b
c
d
p
q
e
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Stroke Sequence
n
m
h
g
u
s
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Example Good and Poor Lettering
GOOD
Not uniform in style.
Not uniform in height.
Not uniformly vertical or inclined.
Not uniform in thickness of stroke.
Area between letters not uniform.
Area between words not uniform.
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Sentence Composition
Leave the space between words equal to the
spacerequires for writing a letter O.
Example
ALL
DIMENSIONS
IN
O
O
O
ARE
MILLIMETERS
O
UNLESS
SPECIFIED.
O
OTHERWISE
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Large Circle

1. Place the little finger (or pencil s tip) at the
   center as a pivot, and set the pencil point at
   the radius-distance from the center.

1. Hold the hand in this position and rotate the
   paper.

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• ? The following figures illustrates the Aligned
  system of dimensioning

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QUADRANT THEORY
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2nd Quadrant
VP
1ST Quad.
2nd Quad.
1st Quadrant
Y
Observer
HP
X Y
X
3rdQuadrant
4th Quad.
3rd Quad.
4th Quadrant
THIS QUADRANT PATTERN, IF OBSERVED ALONG X-Y
LINE ( IN RED ARROW DIRECTION) WILL EXACTLY
APPEAR AS SHOWN ON RIGHT SIDE AND HENCE, IT IS
FURTHER USED TO UNDERSTAND ILLUSTRATION PROPERLLY.
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• ? How to fold the A2 size drawing sheets for
  assignment work?
• ? Mark 190 mm from the right edge of the drawing
  sheet. Mark 186 mm from the previous mark. Mark
  20 mm from the left edge of the drawing sheet.
• ? Mark 297 mm from the bottom edge of the drawing
  sheet on the reverse side.
• ? Coincide the first fold with third fold to get
  second fold. Coincide the third fold with the
  border line which is 20 mm to the right of left
  edge of drawing sheet to get fourth fold. Fifth
  and sixth folds are back folds.
• ? All larger size drawing sheets i.e. A0, A1, A2
  and A3 are folded to A4 size sheet.

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