L E C T U R E 1

ENGN103 ENGINEERING DRAWING

LETTERING, LINES AND SCALE

STRUCTURE OF PRESENTATION

• Introduction

• Tools for Drawing

• Paper sizes

• Title Block

• Dimensioning

• Lettering

• Lines

DRAWING

• Artistic Drawing Technical Drawing

WHY ENGINEERING DRAWING?

• A drawing is a graphic representation of an object,

or a part of it, and is the result of creative thought

by an engineer or technician.

• Engineering Drawing is a formal and precise way of

communicating information about the shape, size,

features and precision of physical objects.

• Drawing is the universal language of engineering.

Engineering drawing ENGN103 Introduction: Overview

DRAWING TOOLS

• To prepare a drawing, one can use: • Manual drafting instruments • Computer-aided drafting or design, or CAD.

• The basic drawing standards and conventions are the same regardless

of what design tool you use to make the drawings.

• In learning drafting, we will approach it from the perspective of manual drafting.

• If the drawing is made without either instruments or CAD, it is called a freehand sketch.

Engineering drawing ENGN103 Introduction: Apparatus

MANUAL DRAFTING TABLE/BOARD

Engineering drawing ENGN103 Introduction: Apparatus

T-SCALE

Engineering drawing ENGN103 Introduction: Apparatus

TRIANGLE / SET-SQUARE

Engineering drawing ENGN103 Introduction: Apparatus

Adjustable Triangle Set-square: 30 & 60, 45

COMPASS

Engineering drawing ENGN103 Introduction: Apparatus

PROTRACTOR

FRENCH CURVE

Engineering drawing ENGN103 Introduction: Apparatus

CIRCLE MASTER

FLEXI-CURVE

Engineering drawing ENGN103 Introduction: Pencils

Engineering drawing ENGN103 Introduction: Paper Size

PAPER SIZES

Engineering drawing ENGN103 Introduction: Paper Size

Engineering drawing ENGN103 Introduction: Title Block

Engineering drawing ENGN103 Introduction: Lettering

• Thick- HB grade pencil

• Medium- H Grade

pencil

• Thin- 4H grade pencil

Engineering drawing ENGN103 Introduction: Lines-Home Work

DRAWING SCALE

• The ratio of the length in a drawing (or model) to

the length of the real thing. 1: 10, 1:1, 1:200 etc

Example: in the drawing anything with the size of "1" would have a size of "10" in the real world, so a measurement of 150mm on the drawing would be 1500mm on the real horse.

• A drawing that shows a real object with accurate

sizes except they have all been reduced or

enlarged by a certain amount (called the scale)is a

scale drawing.

SCALE • When the object is bigger than the size of drawing sheet, it is drawn

at reduced scale.

• Therefore, scale is the ration of actual object and the size shown on

the drawing. The scales are designated as:

• SCALE 1: X for reduced scale (X is the ratio)

• SCALE X:1 for enlarged scale

• SCALE 1:1 for full size

• Standard recommended ratios are multiples of 2, 5 and 10 as:

• Enlargement: 50:1, 20:1, 10:1, 5:1, 2:1

• Reduction: 1:2, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000, 1:2000,

1:5000