GRAPHIC SCIENCE
MEL 110
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WELCOME
Name of teacher – Dr. Rahul Ribeiro
Office: 174 Block III
Email: rribeiro@mech.iitd.ac.in
Off: 011-26591034
Cell: 9910683606
Personal home page- http://web.iitd.ac.in/~rribeiro/
You can also access it by going to ME dept. –
faculty – Rahul Ribeiro – personal web page
All powerpoint files used in this class and other
instructions will be available at my homepage
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under “courses”.
Syllabus and text
 Lettering
 Dimensioning
 Projections (Orthographic, Axonometric, Isometric,
Oblique, Perspective)
 Geometric constructions
 Auxiliary projections
 Projections of lines, planes, solids
 Intersection of surfaces
 Sectioning
 Development of surfaces
 Computer Aided Drawing
Text books: Fundamentals of Engg. Drawing by Luzadder
and
Engineering drawing by N. D. Bhatt
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Classes and marks weightage
Venue, timings:
 2 hrs. of lecture: TUE and WED 10.00 – 11.00
am in Block III LT2
 4 hrs. of Practical in Work Shop 204
Weightage:
 Tutorial and practical - 40%
 Two minor tests – 15% each
 Major test – 30%
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Instructions for equipment
First 3 tutorials/practicals – Will be done
on tracing sheets. Below the tracing
sheets you will place graph or isometric
sheets
You will also need to bring HB pencils and
eraser (no other instruments will be
allowed)
Position of lines and points will be guided
by the graph and isometric sheets below
All items are available in the SCOOPS
shop or at nearby stationary shops
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Instructions for equipment (contd.)
Tutorial 4 onwards you will bring the
following







Approximately 21.5 x 15 in. drawing sheets
Cello tape for fixing sheet to desk
Compass (small and big)
Divider
Pencils (H and 2H)
Mini drafter
Metric scale and eraser
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Mini Drafter (Tutorial 4 onwards)
A mini drafter is a portable device used to draw parallel, inclined and
perpendicular lines speedily. It is mounted on a drawing board at the top left
corner. A drafter consists of a scale, a scale screw, a scale plate, steel bars, a
bar plate and a clamping mechanism
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Additional instructions
 Each tutorial will be given marks out of 10
 All work is to be completed within the 4 practical hrs.
 Students are required to attend every lecture and tutorial
 You can miss upto certain number of classes and
practicals for sickness and other contingencies ONLY
WITH APPROPRIATE DOCUMENTATION AND
APPROVAL
 A missed practical is to be completed within 5 days from
the day of absence by attending a different sections
practical session
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Borders and title block
What is Engineering Graphics?
Pictorial representation of an engineering
component
Made up of points, lines, curves
Follows certain rules of representation
Top view
Top viewing
direction
Front viewing
direction
Front view
Cone
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Example: sectional view of hand wheel
R12
Shot blast
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Section B-B
Section A-A
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LINES
 Lines are like the alphabet of a drawing language.
 Each line is used in a specific sense
 A line may be straight, curved, continuous or segmented
 Segmented may consist of dashes or dots or both
 It may be thick, medium or thin
 Pencil choice: Harder grade for thin lines, softer grade for thick lines




H – Thick and medium
2H – Thin
HB – Freehand
You can also use H for all purposes but make sure to vary intensity by
varying hand pressure
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Different types of lines
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Ref: Engg. Drawing, by Jolhe, McGraw-Hill
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Ref: Engg. Drawing, by Jolhe, McGraw-Hill
Lettering
• Writing of titles, dimensions, notes and other important
particulars on a drawing is known as lettering.
• It should be done in clear, uniform, legible style.
• The main titles are generally written in 6mm to 8mm
size, sub-titles in 3mm to 6mm size, while notes,
dimension etc. in 3mm to 5 mm size.
• For maintaining uniformity in size, thin and light guide
lines may first be drawn and lettering may then be done
between them.
• Use graph sheets to determine the spacing.
• Inclined lettering is drawn at 75o to the horizontal
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Dimensions of lettering
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Example
Gap 1mm
5mm
4mm
Draw in single stroke
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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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Drawings
(Some Types)
Botanical Drawings
( plants, flowers etc.)
Nature Drawings
( landscape,
Geographical
scenery etc.)
Drawings
( maps etc.)
Building Related Drawings.
Orthographic Projections
2-D Views
Portraits
( human faces,
expressions etc.)
Zoological Drawings
(creatures, animals etc.)
Engineering Drawings,
(projections.)
Machine component Drawings
Isometric ( Mech.Engg.Term.)
3-D View
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ORTHOGRAPHIC PROJECTIONS:
IT IS A TECHNICAL DRAWING IN WHICH DIFFERENT VIEWS OF AN OBJECT
ARE PROJECTED ON DIFFERENT REFERENCE PLANES
OBSERVING PERPENDICULAR TO RESPECTIVE REFERENCE PLANE
Different Reference planes are
Horizontal Plane (HP),
Vertical Frontal Plane ( VP )
Side Or Profile Plane ( PP)
And
Different Views are Front View (FV), Top View (TV) and Side View (SV)
FV is a view projected on VP.
TV is a view projected on HP.
SV is a view projected on PP.
IMPORTANT TERMS OF ORTHOGRAPHIC PROJECTIONS:
1 Planes.
2 Pattern of planes & Pattern of views
3 Methods of drawing Orthographic Projections
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VP
2nd
1ST Quad.
Quad.
Y
Observer
HP
X Y
X
3rd Quad.
4th Quad.
THIS QUADRANT PATTERN,
IF OBSERVED ALONG X-Y LINE ( IN RED ARROW DIRECTION)
WILL EXACTLY APPEAR AS SHOWN ON RIGHT SIDE AND HENCE,
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IT IS FURTHER USED TO UNDERSTAND ILLUSTRATION PROPERLLY.
FIRST ANGLE
PROJECTION
FOR T.V.
IN THIS METHOD,
THE OBJECT IS ASSUMED TO BE
SITUATED IN FIRST QUADRANT
MEANS
ABOVE HP & INFRONT OF VP.
OBJECT IS INBETWEEN
OBSERVER & PLANE.
PP
VP
FV
LSV
Y
X
TV
HP
Open the
planes out
ACTUAL PATTERN OF
PLANES & VIEWS
IN
FIRST ANGLE METHOD
OF PROJECTIONS
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2
PATTERN OF PLANES & VIEWS (First Angle Method)
THIS IS A PICTORIAL SET-UP OF ALL THREE PLANES.
ARROW DIRECTION IS A NORMAL WAY OF OBSERVING THE OBJECT.
BUT IN THIS DIRECTION ONLY VP AND A VIEW ON IT (FV) CAN BE SEEN.
THE OTHER PLANES AND VIEWS ON THOSE CAN NOT BE SEEN.
PROCEDURE TO SOLVE ABOVE PROBLEM:TO MAKE THOSE PLANES ALSO VISIBLE FROM THE ARROW DIRECTION,
A) HP IS ROTATED 900 DOUNWARD
B) PP, 900 IN RIGHT SIDE DIRECTION.
THIS WAY BOTH PLANES ARE BROUGHT IN THE SAME PLANE CONTAINING VP.
Click to view Animation
On clicking the button if a warning comes please click YES to continue, this program is
safe for your pc.
PP
VP
Y
FV
LSV
Y
X
X
TV
HP
900
HP IS ROTATED DOWNWARD
AND
BROUGHT IN THE PLANE OF VP.
900
PP IS ROTATED IN RIGHT SIDE
AND
BROUGHT IN THE PLANE OF VP.
ACTUAL PATTERN OF PLANES & VIEWS
OF ORTHOGRAPHIC PROJECTIONS
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DRAWN IN
FIRST ANGLE METHOD OF PROJECTIONS
NOTE
• Front view is also known as
ELEVATION
• Top view is also known as
PLAN
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3
Methods of Drawing Orthographic Projections
First Angle Projections Method
Here views are drawn
by placing object
Third Angle Projections Method
Here views are drawn
by placing object
in 1st Quadrant
in 3rd Quadrant.
( Fv above X-y, Tv below X-y )
(
SYMBOLIC
PRESENTATION
OF BOTH METHODS
WITH AN OBJECT
STANDING ON HP ( GROUND)
ON IT’S BASE.
FV
X
Y
Tv above X-y, Fv below X-y )
TV
NOTE:-
X
1st
TV
HP term is used in
Angle method
&
For the same
Ground term is used
in 3rd Angle method of projections
Y
FV
G
L
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FIRST ANGLE
PROJECTION
FOR T.V.
IN THIS METHOD,
THE OBJECT IS ASSUMED TO BE
SITUATED IN FIRST QUADRANT
MEANS
ABOVE HP & INFRONT OF VP.
OBJECT IS INBETWEEN
OBSERVER & PLANE.
PP
VP
FV
LSV
Y
X
TV
HP
ACTUAL PATTERN OF
PLANES & VIEWS
IN
FIRST ANGLE METHOD
OF PROJECTIONS
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THIRD ANGLE
PROJECTION
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.
TV
X
Y
LSV
FV
ACTUAL PATTERN OF
PLANES & VIEWS
OF
THIRD ANGLE PROJECTIONS
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FIRST ANGLE
PROJECTION
FOR T.V.
IN THIS METHOD,
THE OBJECT IS ASSUMED TO BE
SITUATED IN FIRST QUADRANT
MEANS
ABOVE HP & INFRONT OF VP.
OBJECT IS INBETWEEN
OBSERVER & PLANE.
PP
VP
FV
LSV
Y
X
TV
HP
ACTUAL PATTERN OF
PLANES & VIEWS
IN
FIRST ANGLE METHOD
OF PROJECTIONS
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THIRD ANGLE
PROJECTION
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.
TV
X
Y
LSV
FV
ACTUAL PATTERN OF
PLANES & VIEWS
OF
THIRD ANGLE PROJECTIONS
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FOR T.V.
1
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
x
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
y
TOP VIEW
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FOR T.V.
3
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
X
Y
TOP VIEW
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
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4
FOR T.V.
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
X
Y
TOP VIEW
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
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FOR T.V.
5
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
X
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
Y
TOP VIEW
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6
FOR T.V.
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
X
Y
TOP VIEW
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
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TUT1 Qs. 3
Sketch the 3 orthographic
projections in 1st. angle
FOR T.V.
2
ORTHOGRAPHIC PROJECTIONS
FRONT VIEW
L.H.SIDE VIEW
X
Y
TOP VIEW
PICTORIAL PRESENTATION IS GIVEN
DRAW THREE VIEWS OF THIS OBJECT
BY FIRST ANGLE PROJECTION METHOD
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TUT 1. Qs. 4
Sketch the orthographic views
in 3rd. angle
End of lecture
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