1

Reminder-Instructions for equipmentTutorial 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)

More Hlighter Mini drafter Metric scale and eraser

2

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

a, d

f, gb, c

e, h

d a

bc

h e

fg

Oblique projectionPlane of projection

Projection lines are oblique to the plane

d, h

b, fc, g

a, e

Face abcd retains original shape and dimensions

Drawing an oblique projection

taken as 45o

Oblique view of a cuboid

x

y

z

Axes are drawn such that two of them are perpendicular to each other for the front face (horizontal and vertical) and the third is drawn at a pre-defined angle (use 45o in this course) to horizontal axis

Lines drawn in true length

Receding angle

Receding line

This face will have features with true shape

Draw essential contours (circles, curves etc.) on this face

o

Oblique view

It is a method of drawing a 3-D view of an object (similar to isometric view)

2 axes are mutually perpendicular while the 3rd. axis is at an angle (other than 90o to the other 2 axes)

Object Orientation GuidelinesPlace complex features (arc, hole, irregular shapesurface parallel to frontal plane.

Cavalier and cabinet projection

• Two types of oblique projection– Cavalier projection: When the receding lines are drawn to

full size scale and the projectors are inclined at an angle of 30o, 45o, or 60o

– Cabinet projection: If the receding lines are drawn to half size scale.

We use Cavalier Projection in this course

8

PROJECTIONS OF PLANES

Information usually given:1. Shape of the plane2. Inclination of it’s surface with one of the reference (principal) 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

9HP

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

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

10

X Ya

b c

d

a’b’

c’d’

a1

b1 c1

d1

a1

b1

c1

d1

b’ a’

d’c’ c’1 d’1

b’1 a’1450

300

Rectangle 30mm and 50mm sides is resting on HP on one small side which is 300 inclined to VP, while the surface of the plane makes 450 inclination with HP. Draw it’s projections.

Surface // to Hp Surface inclined to Hp

Side Inclined to Vp

11

Drawing the side view

O45o

TF

F

T

RSVRSV

With O as center draw curves (1/4 circle) to project the corners Draw a line from O at 45o to the

horizontal axis to project the corners

w

w

w

wO

12

Projections of solids

13

SOLIDSDimensional parameters of different solids.

Top

Rectangular Face

Longer Edge

Base

Edge of Base

Corner of base

Corner of base

Triangular Face

Slant Edge

Base

Apex

Square Prism Square Pyramid Cylinder Cone

Edge of Base

Base

Apex

Base

GeneratorsImaginary lines generating curved surface of cylinder & cone.

Sections of solids( top & base not parallel) Frustum of cone & pyramids.( top & base parallel to each other)

Problem:A cone 40 mm diameter and 50 mm height is resting on one generator on Hp which makes 300 inclination with VpDraw it’s projections.

Draw in 1st.angle

h

a

bc

d

e

g

f

X Ya’ b’ d’ e’c’ g’

f’h’

o’ a’h’b’

e’

c’g’d’f’

o’

a1

h1

g1

f1

e1

d1

c1

b1

a1

c1

b1

d1

e1

f1

g1 h1

o1

a’1b’1

c’1d’1e’1

f’1

g’1

h’1

o1

o1

30

Solution Steps:Resting on Hp on one generator, means lying on Hp:1.Assume it standing on Hp.2.It’s Tv will show True Shape of base( circle )3.Draw 40mm dia. Circle as Tv & taking 50 mm axis project Fv. ( a triangle)4.Name all points as shown in illustration.5.Draw 2nd Fv in lying position I.e.o’e’ on xy. And project it’s Tv below xy.6.Make visible lines dark and hidden dotted, as per the procedure.7.Then construct remaining inclination with Vp ( generator o1e1 300 to xy as shown) & project final Fv.