Introduction to engineering drawing

• List of Drawing Instruments and Materials

• Instruments box containing the following minimum items:

• A large compass (150 mm)

• A bow compass with adjusting screws (100 mm)

• A large divider

• A bow divider with adjusting screws (100 mm)

• A good quality drafter

• A pair of set squares: 45°-45°, 30°-60° (250 mm, 2.5 mm thick)

Conventional lines

Type of views

• Isometric

• Orthographic

Chapter 5

Orthographic

Projection

OBSERVER MOVE AROUND

Front view Right side view

Top view

THE GLASS BOX CONCEPT

Bottom view

Left side view

Rear view

Height

Width

De

pth

History

PROJECTION SYSTEMS1. First angle system

2. Third angle system

First Quadrant

ThirdQuadrant

- European country

- ISO standard

- Canada, USA,

Japan, Thailand

ORTHOGRAPHIC PROJECTION

1st angle system 3rd angle system

ORTHOGRAPHIC VIEWS

1st angle system 3rd angle system

Foldingline

Foldingline

Foldingline

Foldingline

ORTHOGRAPHIC VIEWS

1st angle system 3rd angle system

Front View

Front View

Right Side View

Right Side View

Top View

Top View

First angle system Third angle system

PROJECTION SYMBOLS

PROJECTION SYMBOLS

d 1.7d

2.2d

Suggested proportion

Orthographic Writing Steps

WRITING STEPS

1. Select the necessary views

2. Layout the views.

3. Project the views.

4. Dimension the views.

1. SELECT THE NECESSARY VIEWS

45

152

152

64

2. LAYOUT THE VIEWS

A4

25

Choose anappropriate scale

1:1

PROJECT THE VIEWS

DIMENSION THE VIEWS

NOTES1. Dimensions in millimeters.2. ….

PART NAME

xx

x x

y

y

y

y

z

TRANSFERINGTHE DEPTH DIMENSION

1. Direct measurement

01

23

27

0 1 2 3 Starting point27

TRANSFERINGTHE DEPTH DIMENSION

2. Use miter line

45

Views too close

No line is formed when curved surface tangent

to a plane surface.

No line

No line

TANGENT & INTERSECTION

Line is formed when curved surface intersects

a plane surface.

tangent

tangent

intersect

intersect

Orthographic

Projection

of Object Features

OBJECT FEATURES

Edges are lines that represent the boundary

between two faces.

Corners Represent the intersection of two or

more edges.

Edge

Corner

Edge No edge

No corner No corner

Surfaces are areas that are bounded by edges

or limiting element.

Limitingelem

ent

is a line that represents the last visible

part of the curve surface.

Surface Surface Surface

LimitLimit

OBJECT FEATURES

Line Convention

HIDDEN LINE PRACTICE

Hidden line should join a visible line, except itextended from the visible line.

Correct

No !

Join

Leavespace

Correct No !

Hidden line should join a visible line, except itextended from the visible line.

Leavespace

Leavespace

HIDDEN LINE PRACTICE

Hidden line should intersect to form L and Tcorners.

Correct

No !

L T

HIDDEN LINE PRACTICE

Hidden arcs should start on a center line.

HIDDEN LINE PRACTICE

Introduction to AutoCAD

OUTLINE

• Giving commands

• Object snap

• Zooming and panning

• Drawing 2D shapes

• Drawing 3D shapes

• Editing

• UCS

• Assignment

How do we give a command?

• Command line

• Toolbars(view/Toolbars)

• Drop-down menus

You can pick any one(s) that you are comfortable with.

What is OSNAP?• Osnap (Object Snap) settings make it easier to select a 2d

object’s points– Endpoint

– Midpoint

– Perpendicular

– Center

– İntersection

• Osnap will be active when

AutoCAD is expecting you to

pick a point on the working area

• Type osnap on your

command window:

Zooming...• You will need to zoom in and out while drawing with

AutoCAD. This doesnt change your objects or UCS, only the way you see your working space. This can be done in many ways:

1. Scroll bars

2. Typing z or zoom in your command window.

• All

• Center

• Dynamic

• Extents

• Previous

• Scale

• Window

Lets draw a LINE:• remember that AutoCAD recognizes an object by its

coordinates. You will need two given points to draw a line.

• You can start at a random point on your WCS for your FIRST POINT, but you should specify the coordinates of your SECOND POINT.

(x1,y1,z1)

(x2,y2,z2)

What else?• Rectangle: two diagonal lines

(pick first point, select the second one with relation to the first. @5<-33)

• Circle/Arc: center and radius

• Polygon: specify the number of edges and length of a side

A small tip: you can use the EXPLODE command for the tool to split the object into its components or lines

a

b

a

d

d

Editing… • COPY

• MOVE

• MIRROR

ARRAY

SCALE

STRETCH

More editing…• STRETCH

• EXPLODE

OFFSET

ROTATE

ERASE

Polyline (pline) • The PLINE command creates a chain line with

multiple vertexes and straight or circular segments between the vertexes

• Draw a closed shape with the pline command:

• Then type PEDIT (polyline edit) on the command line and see what you can do with it:Enter an option [Close/Join/Width/Edit vertex/Fit/Spline/Decurve/Ltype gen/Undo]:

Try Width and Spline

Hatching

• Hatching is used to add shaded patterns to objects and shapes within an Autocad drawing. Hatch patterns can be used to indicate a material to be used, such as a concrete hatch. Alternatively it could be used to make an area of a drawing stand out.

• You will pick:

– Pattern

– Scale

– Angle

– points

• Solids contain the “mass properties” of 3D objects.

• You can use the Solids toolbar for readily accessible objects

– Box

– Cylinder

– Wedge

• You can use the Boolean operations of more complicated shapes.

– Union (join two solids)

– Subtract (carve out the second solid from the first)

– Intersection (only the common area)

Drawing SOLIDS

Torus

Cone

Sphere

We can create solids by extruding as well

• If you “extrude” a surface into the third dimension, you simply add a thickness in section. This basically is same as creating a “solid” object

Extrude 5 units 5 units

Extrude -4 units

4 units