Engineering drawing

1
Introduction
Chapter 1

• After completing this chapter student can able
  to-
• Know history of engineering drawing
• Understand objectives of engineering drawing
• Identifying standard paper layouts
• Identifying types of instruments for engineering
  drawing
• Identifying alphabet lines
• Writing technical lettering
• know types of scaling

2
Introduction

• Drawing is an art of representing objects or
  forms on a flat surface by means of lines, using
  any of a wide variety of tools and techniques.
• An engineering drawing is a type of technical
  drawing, used to fully and clearly define
  requirements of engineered items,
• And it is usually created in accordance with
  standardized conventions for
• layout,
• nomenclature,
• interpretation,
• appearance size etc.

3
Introduction

• Types of Engineering drawing Based on the major
  engineering branches, engineering drawing can be
  classified as follows

4
Introduction

• Mechanical engineering drawings
• Some examples of mechanical engineering drawings
  are part and assembly drawings, riveted joints,
  welded joints, fabrication drawings, pneumatics
  and hydraulics drawings, pipeline diagrams, keys
  coupling drawings etc.
• Electrical Engineering drawings
• Wiring diagrams of home and industries, circuit
  diagrams, electrical installation drawings etc.

5
Introduction

• Electronics Engineering drawings
• Circuit drawings, PCB tracks drawings etc.
• Civil Engineering drawings
• Plan, front elevation of homes to be built,
  foundation drawings, etc.

6
Introduction

• Engineering as communication
• It is the process of conveying feelings/informatio
  n

7
Introduction

• Graphics Language
• The word languages are inadequate for describing
  the size, shape and features completely as
  well as concisely.
• Graphic language in engineering application
  use lines to represent the surfaces, edges and
  contours of objects.
• The language is known as drawing or
  "drafting
• A drawing can be done using freehand,
  instruments or computer methods.

8
Freehand drawing The lines are sketched without
using instruments other than pencils and erasers.
9
Instrument drawing Instruments are used to draw
straight lines, circles, and curves concisely
and accurately. Thus, the drawings are usually
made to scale.
10
Computer drawing The drawings are usually made
by commercial software such as AutoCAD, solid
works etc.
11
Elements of Engineering Drawing
Engineering drawing are made up of graphics
language and word language.
12
History of Engineering drawing

• Drawing is universal language that human beings
  have being using to communicate the visual image
  in their mind
• It is such an old practice that its recorded
  history could be as old as humanity
• The is evidence that as far back as 12000 B.C.,
  ancient cave were inscribed with drawing that
  give clues to some human experiences in
  prehistoric time.
• Technical engineering drawing might have been
  existed before written language

13
History of Engineering drawing

• At inception, technical drawing were drawn with
  hands by using tools that can be regarded as
  primitive of present manual (traditional)
  technical drawing tools
• set square,ruler,protractor and compass it was
  about 5000 years before the beginning of
  engineering and architectural drawing and
  drafting.
• The ancient Greek civilization has had a great
  deal of influence on modern- day drawing through
  its work in geometry.
• Many of manual tools such as compass triangles
  were developed when Greek civilization were peak

14
History of Engineering drawing

• 14th and 15th century
• Engineering drawings representing machines and
  buildings
• Leonardo da Vincis(1452-1519
• Italian artist, inventor, and mapmaker
• Created pictorial drawings generally without
  dimensions
• Gas pared Monge, French mathematician, introduced
  theory of projection at the end of 18th century
• It is deeply rooted in our sense that it is our
  own universal language even today

15
History of Engineering drawing

• Leon Battista Alberti (1404-1472)
• Italian architecture and engineering author
• Explored the need to incorporate more geometry in
  drawings
• Proposed drawings with multiple views
• René Descartes (1596-1650)
• French inventor of the Cartesian coordinate
  system
• Founder of analytic geometry

16
Objective of engineering drawing

• The main objective of Engineering Drawing is
• Increase imagination power
• to turn ideas into Products.
• Every product we have today (cars, houses, beds,
  tables, appliances, tools, packages, clothing,
  toys, dishes, radios, CD players, roads, bridges,
  airplanes, ships, computers, telephones, fax
  machines, copiers, air-conditioners, light bulbs,
  keys, etc.) began as an "idea" in some person's
  head. Before these "ideas" became products, they
  had to be drawn on paper.

17
Objective of engineering drawing

• To know about different types of lines use of
  different types of pencils in an Engineering
  Drawing
• To know how to represents letters numbers in
  drawing sheet
• To know about different types of projection
• To know projection of points ,straight lines,
  solids etc.

18
Objective of engineering drawing

• To know development of different types of
  surfaces.
• To know about isometric projection.
• Basics of dimensioning ,Lettering representation
  of lines
• Different lines used for representation of
  different Engineering Sections.
• To know different angle of projection.

19
DRAWING SHEET

• In engineering drawing there are various standard
  paper sheet
• Standards are set of rules that govern how
  technical drawings are represented.
• Drawing standards are used so that drawings
  convey the same meaning to everyone who reads
  them.

20
Standard Code
21
DRAWING SHEET

• A drawing sheet comprises a thick paper onto
  which the drawing is made.
• It is available in standard thickness and size.
• The thickness is specified by weight in grams
  per square metre (gsm).
• A sheet with 150 to 250 gsm is suitable for
  drawing. Size of the sheet depends upon the size
  of drawing.

22
DRAWING SHEET

• Based on ISO standard the A-series papers are
  sized as follows
• This series of paper always has a length-to-width
  ratio 2 1rounded of nearest millimeter
• A0 has an area of 1 square metre.
• Successive sizes in the series are designated as
  A1, A2, A3, etc., which are obtained by halving
  the preceding size.

23
Paper sizes for ISO-A series
Series Paper size (mm mm)
A0 210 x 297
A1 297 x 420
A2 420 x 594
A3 594 x 841
A4 841 x 1189
24
DRAWING INSTRUMENTS

• Following is a list of common drawing instruments
  and accessories

1. French curves
2. Set squares
3. Eraser or rubber
4. Sheet fasteners
5. Template
6. Pencil cutter
7. Sand paper pad
8. Brush or towel cloth

1. Drawing board
2. Mini drafter
3. Drawing sheet
4. Drawing Pencil
5. Compass (pivot joint type and spring bow type)
6. Divider (pivot joint type and spring bow type
7. Protractor
8. 8. Ruler (scale

25
DRAWING INSTRUMENTS

• DRAWING BOARD
• It is made of softwood which provides a flat
  surface.

(a)
(b)
Drawing board(a) Conventional (b) Modern

26
DRAWING INSTRUMENTS

• Designation and size of Drawing Board

Designation Length Width Tolerance onLength/Width Thickness Tolerance onThickness Recommended for usewith sheet sizes
D00 1525 1220 5 22 1 A0
D0 1270 920 5 22 1 A0, A1
D1 920 650 5 22 1 A1, A2
D2 650 470 5 22 1 A2, A3
D3 500 350 5 22 1 A3, A4

27
DRAWING INSTRUMENTS

• Mini-drafter

(a)
(b)
(a) Mini-drafter (b) Clamping mini-drafter
28
Rolling Ruler
DRAWING INSTRUMENTS
29
T-square
DRAWING INSTRUMENTS
The T-square serves as a guide for the
set-squares for drawing parallel lines at
commonly used angles 30º, 45º and 60º
30

DRAWING INSTRUMENTS

• Sheet holder

31
DRAWING INSTRUMENTS

• DRAWING PENCIL
• Pencils are graded according to the proportion of
  graphite to clay mixture in the pencil lead.
• A set of pencils ranges from hardest to softest
  as follows

32
DRAWING INSTRUMENTS

• Spring bowcompass

Spring bow compass
(a) Pivot joint compass (b) Legs bended at knee
joints (c) Extension arm inserted to draw large
circles
33
DRAWING INSTRUMENTS

• DIVIDER

Pivot joint divider
Spring bow divider
34
DRAWING INSTRUMENTS

• PROTRACTOR

Protractor (a) Semi-circular (b) Circular
35
DRAWING INSTRUMENTS
RULER (SCALE)
FRENCH CURVES
36
DRAWING INSTRUMENTS

• triangls
• Straightedge
• Draw angles
• Connect points
• 3060 triangle
• Angles of 306090
• 45 triangle
• Angles of 454590

37
DRAWING INSTRUMENTS
DRAWING TOOLS
Pencil Eraser
Erasing Shield
38
DRAWING INSTRUMENTS

• SHEET FASTENERS

Sheet fasteners (a) Drawing pins (b) Drawing clip
(c) Adhesive tape
39
DRAWING INSTRUMENTS

• TEMPLATES

(a) General purpose
(b) Lettering
40
DRAWING INSTRUMENTS

• PENCIL CUTTERS

Sharpeners (a) Conventional (b) Blade cutter
(c) Mechanical
41
DRAWING INSTRUMENTS

• Sand paper pad

Brush