ENGINEERING GRAFICS UNIT 1 FIRST YEAR PDF

This is pdf of Engineering graphic
Which is a subject tought in IPU affiliated college
In this pdf every thinh about Engeneering graphics is present
Which is very useful for IPU and IPU affiliated college Students

1. Introduction
Drawing Instruments
Lines
Dimensioning
Scale
Quadrant System

2. Graphical means of expression of technical details
without the barrier of a language.
Universal language for engineers
Engineering Drawing
Drawing
Describing any object/ information diagrammatically

3. Graphical representation of an object –Drawing
• Engineering drawing–A drawing of an object that
contains all information
-like actual shape, accurate size,manufacturing
methods,etc., required for its construction.
-No construction/manufacturing of any (man -made)
engineering objects is possible without engineering
drawing.

4. Computer has a major impact on the methods used to design and create technical
drawings.
Design and drafting on computer are cheap and less time consuming.
Why we go for manual drawing?
Engineering Drawing
Manual Drawing CADD

5. Computer cannot replace the drafting board and equipment as a
learning tool.
Once you have learned the basics of mathematics, now after
class 12, you are allowed the use of calculator and computer.
If basic fundamentals are clear, better use can be made of the
power of the software.
To be an expert in technical drawing, this first course on
Engineering (manual) Drawing is the first step.
Why we go for manual drawing?

6. Instruments required for drawing
Drawing board
Drawing sheet
Mini-drafter/drafting machine/ T-square
Instrument box containing compass, divider, etc.
Scales
Protractor
French curves
Drawing pencils
Eraser
Drawing clip/pin/adhesive tape
Sharpener
Duster

7. Drawing Sheet : Standard size
Trimmed paper of
a size A0 ~ A4.
Standard sheet size
(BIS)
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)

8. Mini-drafter –a miniature version of the drafting machine

9. Mini-drafter fixed on drawing board

10. Lay out of a drawing sheet

11. 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
• HBto F –Medium grade
• H, 2H,3H, 4H, 5H, 6H, 7H, 8H, 9H –increasing order of
hardness.
Drawings are done using 2H pencils and finished with H
and HB pencils –to be practiced in this course.

12. Grades and designation of wooden pencils

13. Line types

14. Line types….CONTD

15. Units of Measure
International systems of units (SI) –which is based on the meter.
Millimeter (mm) -The common SI unit of measure on engineering
drawing.
Individual identification of linear units is not required if all
dimensions on a drawing are in the same unit (mm).
The drawing shall however contain a note:
ALL DIMENSIONS ARE IN MM.
(Bottom left corner outside the title box)

16. Dimensioning
Indicating on a drawing, the size of the object and other
details essential for its construction and function, using lines ,
numerals, symbols, notes, etc.
Dimensions indicated on a drawing should be those that are
essential for the production, inspection and functioning of the
object and should not be mistaken as those that are required
to make the drawing of an object.

17. Extension
Lines
Dimension Text Dimension Lines
Arrow Heads

18. Dimensions are represented on a drawing
using one of two systems, unidirectional or
aligned.
The unidirectionalmethod means all
dimensions are read in the same direction.
The alignedmethod means the dimensions
are read in alignment with the dimension
lines or side of the part, some read
horizontally and others read vertically.

19. Dimension Text
Unidirectional vs. Aligned
Unidirectional
dimensions are placed
so they can be read from
the bottom of the
drawing sheet. This
method is commonly
used in mechanical
drafting.
Aligneddimensions are placed
so the horizontal dimensions can
be read from the bottom of the
drawing sheet and the vertical
dimensions can be read from the
right side of the drawing sheet.
This method is commonly used in
architectural and structural
drafting.

20. Chain Dimensioning
Dimensioning from feature to feature
is known as Chain Dimensioning.. It
is commonly used and easy to lay
out. It does have possible
consequences in the manufacturing
of a part. Tolerances can
accumulate, making the end product
larger or smaller than expected.

21. Chain Dimensioning
This is a general note. It
indicates that all two
place decimal
dimensions have a
tolerance of plus or
minus .01 inch unless
otherwise specified.

22. Datum(parallel) Dimensioning
The accuracy of the final product is
determined by the dimensions on the
drawing. If all the dimensions originate
from a common corner of the part, the
object will be more accurate. This is
referred to asDatumDimensioning.
Datums insure the tolerance or errors in
manufacturing do not accumulate.

23. Datum Dimensioning
The dimensions originate
from a common edge
(DATUM)of the part.

24. Coordinate dimensioning

25. Dimensioning Curved Features
and Arcs
Use a capital “R” for
dimensioning arcs.
Large Arcs use center
marks.
Small arcs do not need
center marks. Arrow can
be outside.
The arrow can be inside
for small arcs.

26. Diameters
A full circular object should be dimensioned
using its diameter. Holes should use hole
notes.
This specification
calls for a hole with
a .5 diameter
and 1.00 deep.

27. Diameters
Cylindrical parts may show their diameters in this
manner. Dimensioning on the right side view
could be too crowded.
Note that the diameter symbol is used so it
is not confused with a linear dimension.

28. Chamfers
External chamfer for 45 degree
chamfers only.
There are two options.
External chamfer for angles other than
45 degrees.
Internal chamfers.

29. Drawing Scales : Definition
Drawing Actual
Length, size
:
Scaleis a ratio between the linear dimension of a
drawn representation of an object and the actual object.
1 2
20
10

30. Designation of a scale consists of the word “SCALE”
followed by the indication of its ratio, as follows
SCALE 1:1for full size
SCALE X:1(X > 1) for an enlargementscales
SCALE 1:X(X > 1) for a reductionscales
Drawing Scales : Designation
Drawing scale is commonly found in a title block.

31. Standard reducingscales are
1:2, 1:5, 1:10, 1:20, 1:50, 1:100
Drawing Scales : Standard scale
Standard enlargingscales are
2:1, 5:1, 10:1, 20:1, 50:1, 100:1

32. 3
2FRP/V.P.
HRP/ H.P.
FRONT
DIRECTION
X
Y
I
II
III
IV
FOUR QUADRANTS
TOP
DIRECTION

33. X
Y
1
ST
Quad.
2
nd
Quad.
3
rd
Quad. 4
th
Quad.
X Y
VP
HP
Observer
THIS QUADRANT PATTERN,
IF OBSERVED ALONG X -Y LINE ( INREDARROW DIRECTION)
WILL EXACTLY APPEAR AS SHOWN ON RIGHT SIDE AND HENCE,
IT IS FURTHER USED TO UNDERSTAND ILLUSTRATION PROPERLLY.

34. 3
4 V.P.
H.P.
FRONT
DIRECTION
X
Y
1st QUADRANT
TOP
DIRECTION
1
st
ANGLE
Projection

35. FOR T.V. FIRST ANGLE
PROJECTION
IN THIS METHOD,
THE OBJECT IS ASSUMED TO BE
SITUATED IN FIRST QUADRANT
MEANS
ABOVE HP & INFRONT OF VP.
OBJECT IS INBETWEEN
OBSERVER & PLANE.
ACTUAL PATTERN OF
PLANES & VIEWS
IN
FIRST ANGLE METHOD
OF PROJECTIONS
X Y
VP
HP
PP
FV LSV
TV

36. FOR T.V.
IN THIS METHOD,
THE OBJECT IS ASSUMED TO BE
SITUATED IN THIRD QUADRANT
( BELOW HP & BEHIND OF VP. )
PLANES BEING TRANSPERENT
AND INBETWEEN
OBSERVER & OBJECT.
ACTUAL PATTERN OF
PLANES & VIEWS
OF
THIRD ANGLE PROJECTIONS
X Y
TV
THIRD ANGLE
PROJECTION
LSV FV

37. Methods of Drawing Orthographic Projections
First Angle Projections Method
Here views are drawn
by placing object
in 1
st
Quadrant
( Fv above X-y, Tv below X-y )
Third Angle Projections Method
Here views are drawn
by placing object
in 3
rd
Quadrant.
( Tv above X-y, Fv below X-y)
FV
TV
X Y X Y
G L
TV
FV
SYMBOLIC
PRESENTATION
OF BOTH METHODS
WITH AN OBJECT
STANDING ON HP ( GROUND)
ON IT’S BASE.
NOTE:-
HP term is used in 1
st
Angle method
&
For the same
Ground term is used
in 3
rd
Angle method of projections