ENGINEERING GRAPHICS By R.Nathan Assistant Professor Department of Mechanical Engineering

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ENGINEERING GRAPHICSBy R.NathanAssistant
ProfessorDepartment of Mechanical Engineering
C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
20.09.2012
2
UNIT 1BASICS OF ENGINEERING GRAPHICS

• Engineering Graphics Lecture Notes

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

PENCIL GRADES
C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
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18.09.2012
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• Engineering Graphics
  Lecture Notes

Types of Lines
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• Engineering Graphics
  Lecture Notes

Types of Lines
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• Engineering Graphics
  Lecture Notes

Example for Lines
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• Engineering Graphics
  Lecture Notes

Pencil Holding Technique
C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
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• Engineering Graphics
  Lecture Notes

ALPHABETS FOR TITLE BLOCK
C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

ALPHABETS FOR TITLE BLOCK (FOR LEFT HAND USERS)
C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

LIST OF DRAWING EQUIPMENTS MATERIALS

1. DRAWING BOARD
2. MINI DRAFTER
3. DRAWING SHEET
4. PENCILS (HB, 2H, 4H, 2B, 4B etc)
5. NON DUST RUBBER
6. SCALES (150 mm 300 mm)
7. INSTRUMENT BOX
8. SET SQUARES (30, 45, 60 etc..)
9. DRAWING BOARD CLIPS, CLAMPS, PINS, CELLO TAPE
10. PROTECTOR or PROCIRCLE or CIRCLE MASTER
11. PENCIL SHARPENER
12. SMALL PAPER KNIFE or STITCHING THREAD to cut the
    sheetS
13. A HANDKERCHIEF or HAND TOWEL

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
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18.09.2012
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• Engineering Graphics
  Lecture Notes

DRAWING BOARD
ERASER
SCALES
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• Engineering Graphics
  Lecture Notes

COMPASS
BOW COMPASS
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• Engineering Graphics
  Lecture Notes

DIVIDER
BOW DIVIDER
SET SQUARES
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• Engineering Graphics
  Lecture Notes

DRAWING CLIPS, CLAMPS,
PROTRACTOR
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PAPER KNIFE or STITCHING THREAD
CIRCLE MASTER or PRO-CIRCLE
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• Engineering Graphics
  Lecture Notes

ROLLER
MINI DRAFTER
INSTRUMENT BOX
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• Engineering Graphics
  Lecture Notes

HOW TO KEEP DRAWING SHEET CLEAN

1. ALWAYS CLEAN YOUR HANDS INSTRUMENTS BEFORE
   FIXING THE DRAWING SHEET
2. HANDS SHOULD BE FREQUENTLY WIPED WITH CLEAN
   HANDKERCHIEF
3. THE SET SQUARES MAY BE LIGHTLY MOVE WITH THE
   FINGER NAILS WHILE USING
4. CLEAN PENCIL SMULGE WITH A CLEAN CLOTH
5. THE RUBBER PPOWER OF PENCIL IS REMOVED AWAY FROM
   THE DRAWING SHEET
6. DRAWING SHEET SHOULD BE ERASED WITH A SOFT
   RUBBER ONLY
7. REMOVE RUBBER DUST WITH A CLEAN PIECE OF CLOTH or
   HANDKERCHIEF
8. DO NOT KEEP ANYTHING or ARTICLE ON THE DRAWING
   SHEET
9. AVOID UNNECCESARY RUBBING OF LINES
10. DO NOT TOUCH DRAWING SHEET WITH DIRECT HANDS

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
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• Engineering Graphics
  Lecture Notes

DIMENSIONING
ARROWS
SYMBOLS
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TYPES OF DIMENSIONING
1. CHAIN DIMENSIONING
2. DIMENSIONING FROM A COMMON FEATURE
3. PARALLEL DIMENSIONING
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TYPES OF DIMENSIONING
4. SUPER IMPOSED RUNNING DIMENSIONING
5. COMBINED DIMENSIONING
6. PROGRESSIVE DIMENSIONING
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SYSTEM OF PLACING DIMENSION
1. ALIGNED SYSTEM
2. UNIDIRECTIONAL SYSTEM
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• Engineering Graphics
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TYPES OF DIMENSIONING
DIMENSIONING IN THE HATCHING
DIMENSIONING ANGLES
DIMENSIONING CIRCLES
DIMENSIONING ARCS
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• Engineering Graphics
  Lecture Notes

CORRECT INCORRECT METHODS OF DIMENSIONING
CORRECT METHOD
INCORRECT METHOD
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• Engineering Graphics
  Lecture Notes

TYPES OF TRIANGLES
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• Engineering Graphics
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CONSTRUCTION OF TRIANGLES
1. Construct an equilateral triangle given the
length of the side 50 mm

• Solution-
• Method 1 (using Compass)
• Draw a line AB of 50 mm length
• With centres A B and radius equal to 50 mm draw
  arcs intersecting each other at C
• Draw lines joining C with A and B.
• Now, ABC is the required equilateral triangle

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF TRIANGLES
2. Construct an equilateral triangle given the
length of the side 50 mm

• Solution-
• Method 2(using Set Squares)
• Draw a line AB of 50 mm length
• Draw a line through A, making 60 angle with AB
• Similarly through B, draw a line making the same
  angle with AB
• Intersecting point is C
• Now, ABC is the required equilateral triangle

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
27

• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF TRIANGLES
3. Construct a triangle given the altitude 55
mm and two base angles 40 and 65

• Solution-
• Let ?A and ?B are the given base angles and CD be
  the altitude
• Steps Involved-
• Draw a base line of any convenient length
• Draw a - at a point D
• Make CD equal to the given altitude 55 mm
• Through C, draw a line EF to AB
• Make ?ECA 40, ?FCB 65
• Thus ABC is the required triangle

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF SQUARE

1. Construct a square ABCD with AB 60 mm

• Solution-
• Steps Involved-
• Draw a line segment AB of 60 mm
• At A, draw a perpendicular at B.
• With A as centre, 60 mm as radius draw an arc and
  to intersect the - to get the point D
• With B as centre, 60 mm as radius draw an arc and
  to intersect the - through B, to get the point C.
• Now ABCD, is the perfect square

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF RECTANGLE

1. Construct a rectangle PQRS when PG 70 mm, QR
   50 mm

• Solution-
• Steps Involved-
• Draw a line segment PQ of 70 mm long
• At P and Q erect perpendiculars
• With P as centre, 50 mm as radius draw an arc,
  to cut the - at the point S
• With Q as centre, 50 mm as radius draw an arc, to
  cut the - at the point R
• Join R with S
• Now PQRS is the required rectangle

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF RHOMBUS

1. Construct a rhombus ABCD, having its side equal
   to 40 mm and base angle at B of 105

• Solution-
• Let us use the properties of rhombus here.
• All sides of a rhombus are equal
• Steps Involved-
• Draw a line segment AB of 40 mm length
• At B, draw a line BX at an angle of 105
• B as centre 40 mm as radius draw an arc to cut
  the line BX. Intersection point is C
• With A and C as centres, 40 mm as radius draw
  arcs, intersecting point is D
• Join A with D and C with D
• Thus ABCD is the required rhombus

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF RHOMBUS

1. Construct a rhombus PQRS with diagonals 46 mm and
   QS 60 mm

• Solution-
• We know that, the diagonals of a rhombus bisect
  each other at right angles
• Steps Involved-
• Draw a line segment QS of 60 mm length
• Draw a bisector of QS which passes through the
  point O
• With O as centre, ½ PR (23 mm) as radius draw
  arcs above and below to cut the - bisector.
  Intersection points are P R
• Draw lines joining P with Q S.
• Thus PQRS is the required rhombus

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
  Lecture Notes

CONSTRUCTION OF QUADRILATERAL

1. Construct a Quadrilateral with AB 45 mm, BC
   55 mm, CD 40 mm, AD 60 mm, AC 70 mm.

• Solution-
• From our earlier classes, we learnt that, to draw
  a quadrilateral, minimum five dimensions are
  required. Let u now draw this quadrilateral.
• Steps Involved-
• Draw AB of 45 mm length
• With B as centre, 55 mm as radius draw an arc
• With A as centre, 70 mm as radius draw an arc to
  cut the previous arc at the point C
• With C as centre, 40 mm as radius draw an arc
• With A as centre, 60 mm as radius cut the
  previous arc to get the intersection point D
• Draw lines joining D with C and A
• Thus ABCD is the required quadrilateral

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012
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• Engineering Graphics
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CONSTRUCTION OF TRAPEZIUM

1. Construct a trapezium ABCD, having its sides AD
   30 mm, DC 25 mm, CB 35 mm and the difference
   of parallel sides is 20 mm

• Solution-
• Steps Involved-
• Draw a line segment AB of 45 mm, difference
  between parallel sides 20 mm (20 2545 mm)
• With A as centre and 30 mm as radius draw an arc
• With E as centre 35 mm as radius draw an arc to
  cut the previous arc (ie EDBC)
• Intersecting point is D. D as centre 25 mm as
  radius draw an arc
• With B as centre, 35 mm as radius cut the
  previous arc. Intersection point is C
• Draw lines joining A with D, D with C and C with
  B
• Thus ABCD is the required trapezium

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
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• Engineering Graphics
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CONSTRUCTION OF POLYGONS
HEPTAGON
OCTAGON
NONAGON
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• Engineering Graphics
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CONSTRUCTION OF PENTAGON

1. Construct a regular pentagon given the lengh of
   its side as 40 mm

• Solution-
• Draw a line segment AB of 40 mm length
• At B, draw a perpendicular BL such that BK AB,
  join A with K
• With B as centre, AB as radius draw an arc (ie
  arc AK)
• Draw a perpendicular bisector of AB
• Mark the point of intersection of perpendicular
  with line AK as 4 and arc AK as 6
• Mark a point 5 which is the midpoint of 4-6
  obtained by bisecting it
• With 5 as centre and 5A as radius draw a circle
• With B as centre and radius AB, draw an arc to
  cut the circle at C
• In a similar way, set off the measurement of side
  along the circle to get the points D and E
• Draw lines joining B with C, C with D, D with E
  E with A

C.R.ENGINEERING COLLEGE Alagarkovil, Madurai -
625301
I - SEMESTER
18.09.2012