CAEG LAB BY RK SIR

Computer Aided Engineering Graphics[RCE-101/201]

Govt. Engineering College Mainpuri [U.P.]

Lecture Prepared by: R.K. Gautam B.tech [Civil Engg.]

M.tech [Transportation Engg.]

2

NOTATIONS

FOLLOWING NOTATIONS SHOULD BE FOLLOWED WHILE NAMEINGDIFFERENT VIEWS IN ORTHOGRAPHIC PROJECTIONS.

IT’S FRONT VIEW a’ a’ b’

OBJECT POINT A LINE AB

IT’S TOP VIEW a a b

IT’S SIDE VIEW a” a” b”

3

X

Y

1ST Quad.2nd Quad.

3rd Quad. 4th Quad.

X Y

VP

HP

Observer

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.

4

HP

VPa’

a

A

POINT A IN1ST QUADRANT

OBSERVER

VP

HP

POINT A IN2ND QUADRANT

OBSERVER

a’

a

A

OBSERVER

a

a’

POINT A IN3RD QUADRANT

HP

VP

A

OBSERVER

a

a’POINT A IN4TH QUADRANT

HP

VP

A

Point A is Placed In different quadrantsand it’s Fv & Tv are brought in same plane for Observer to see clearly. Fv is visible asit is a view on VP. But as Tv is a view on Hp, it is rotateddownward 900, In clockwise Direction (in 1st quadrant).The In front part of Hp comes below xy line.

The HP behind the Vp is also rotated clockwise, and thereforecomes above the xy line.

Observe and note the process.

Convention: Horizontal plane is always rotated clockwise

PROJECTIONS OF A POINT IN THE 4 QUADRANTS

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HP

VP

POINT IN 2nd QUADRANT

VP

HP

PT

PF

HP

VP

POINT IN 3rd QUADRANT

HP

VP

POINT IN 4th QUADRANT

VP

VP

HPHP

PT: TOP VIEW

PF: FRONT VIEW

PF

PT

PF

HP

VP

POINT IN 1st QUADRANT

VP

HP

PT

PF

PT

P

PP

P

How you will draw on the sheet

6

POINT IN 2nd QUADRANT

PT

PF

POINT IN 3rd QUADRANT

POINT IN 4th QUADRANT

PT: TOP VIEW

PF: FRONT VIEW

PF

PT

PF

POINT IN 1st QUADRANT

PT

PF

PT

y

yy

y

xx

xx

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A

a

a’ A

a

a’

Aa

a’

X

Y

X

Y

X

YFor Fv

For Tv

For Fv

For Tv

For Tv

For Fv

POINT A ABOVE HP& INFRONT OF VP

POINT A IN HP& INFRONT OF VP

POINT A ABOVE HP& IN VP

PROJECTIONS OF A POINT IN FIRST QUADRANT.

ORTHOGRAPHIC PRESENTATIONS OF ALL ABOVE CASES.

X Y

a

a’

VP

HP

X Y

a’

VP

HP

a X Y

a

VP

HP

a’

Fv above xy,Tv below xy.

Fv above xy,Tv on xy.

Fv on xy,Tv below xy.

Projection of lines, planes, solids

•Line – consists of 2 points•Plane – consists of 3 or more points•Solid – consists of more than 3 points

Therefore in order to project lines, planes and solids, we need to project their corresponding points and join them

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9

SIMPLE CASES OF THE LINE

1. A VERTICAL LINE ( LINE PERPENDICULAR TO HP & // TO VP)

2. LINE PARALLEL TO BOTH HP & VP.

3. LINE INCLINED TO HP & PARALLEL TO VP.

4. LINE INCLINED TO VP & PARALLEL TO HP.

5. LINE INCLINED TO BOTH HP & VP.

PROJECTIONS OF STRAIGHT LINES.AIM:- TO DRAW IT’S PROJECTIONS - FV & TV.

INFORMATION REGARDING A LINE: IT’S LENGTH, POSITION OF IT’S ENDS WITH HP & VPIT’S INCLINATIONS WITH HP & VP

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X

Y

V.P.

X

Y

V.P. b’

a’

b

a

F.V.

T.V.

a b

a’

b’

B

A

TV

FV

A

B

X Y

H.P.

V.P. a’

b’

a b

Fv

Tv

X Y

H.P.

V.P.

a b

a’ b’Fv

Tv

For Fv

For Tv

For Tv

For Fv

Note:Fv is a vertical lineShowing True Length&Tv is a point.

Note:Fv & Tv both are// to xy & both show T. L.

1.

2.

A Line perpendicular to Hp & // to Vp

A Line // to Hp & // to Vp

Orthographic Pattern

Orthographic Pattern

(Pictorial Presentation)

(Pictorial Presentation)

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A Line inclined to Hp and parallel to Vp(Pictorial presentation)

X

Y

V.P.

A

B

b’

a’

b

a

F.V.

T.V.

A Line inclined to Vp and parallel to Hp(Pictorial presentation)

Ø

V.P.

a b

a’b’

BAØ

F.V.

T.V.

X Y

H.P.

V.P.

F.V.

T.V.a b

a’

b’

X Y

H.P.

V.P.

Øa

b

a’ b’

Tv

Fv

Tv inclined to xyFv parallel to xy.

3.

4.

Fv inclined to xyTv parallel to xy.

Orthographic Projections

True Length

True Length

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X

Y

V.P.

For Fva’

b’

a b

B

A

For Tv

F.V.

T.V.

X

Y

V.P.

a’

b’

a b

F.V.

T.V.

For Fv

For Tv

B

A

X Y

H.P.

V.P.

a

b

FV

TV

a’

b’

A Line inclined to both Hp and Vp(Pictorial presentation)

5.

Note These Facts:-Both Fv & Tv are inclined to xy.(No view is parallel to xy)Both Fv & Tv are reduced lengths.(No view shows True Length)

Orthographic ProjectionsFv is seen on Vp clearly.To see Tv clearly, HP is rotated 900 downwards,Hence it comes below xy.

On removal of objecti.e. Line ABFv as a image on Vp.Tv as a image on Hp,

and are NOT the true angles (inclinations) of the line with the planes

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PROJECTIONS OF PLANES

Information usually given:1. Shape of the plane2. Inclination of it’s surface with one of the reference planes3. Inclination of one of it’s edges with the other reference plane will be given

A plane is a two-dimensional geometrical entity

It has length and width but no thickness

For practical purposes, a flat face of an object may be treated as a plane

A plane which has limited extent (has fixed shape) is termed as a lamina

14HP

a 1

b 1

c 1

d 1

VPVP

a’

d’c’

b’

VP

a’ d’c’b’

For Fv

For T

v

For F.V.

For

T.V.

For

T.V.

For F.V.

HP

a

b c

d

a1’

d1’ c1’

b1’

HP

a1

b1 c1

d1

CASE OF A RECTANGLE – OBSERVE AND NOTE ALL STEPS.

SURFACE PARALLEL TO HPPICTORIAL PRESENTATION

SURFACE INCLINED TO HPPICTORIAL PRESENTATION

ONE SMALL SIDE INCLINED TO VPPICTORIAL PRESENTATION

ORTHOGRAPHICTV-True Shape FV- Line // to xy

ORTHOGRAPHICFV- Inclined to XYTV- Reduced Shape

ORTHOGRAPHICFV- Apparent ShapeTV-Previous Shape

A B C

Center linesDrawn to indicate the axis of cylindrical, conical or spherical objects or details.

Thin long chains composed of alternately long and short dashes.

Longer dashes are approximately 6 to 8 times the short dashes in length.

Center of a circular curve is indicated by a crossmade up of centerline chains.

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16

x y

FRONT VIEW

TOP VIEW

L.H.SIDE VIEWFOR F.V.

FOR S.V.

FOR T.V.

PICTORIAL PRESENTATION IS GIVENDRAW THREE VIEWS OF THIS OBJECT

BY FIRST ANGLE PROJECTION METHOD

ORTHOGRAPHIC PROJECTIONS

3rd. Angle projection

Front view

Top view

Right Side view

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FOR F.V.FOR S.V.

FOR T.V.

ORTHOGRAPHIC PROJECTIONS

X Y

FRONT VIEW

TOP VIEW

L.H.SIDE VIEW

PICTORIAL PRESENTATION IS GIVENDRAW THREE VIEWS OF THIS OBJECT

BY FIRST ANGLE PROJECTION METHOD