Engineering Drawing

ME 203

2013-2014

Introduction

• Course Aim– Projection & assembly of mechanical elements – Draw different mechanical elements with suitable

fits and tolerances

Introduction

• Course content – Machine drawing standards – Threaded fasteners – Locking devices – Power screws– Springs – Keys and cotters– Bearings – Gears – Welding joints

Introduction

• Teaching and learning methods – Lectures– Tutorial

• Student assessments– 9th week exam (written) 20%– Continues assessment (in class & homework,

quizzes) 30%– Final assessment (written) 50%

Introduction

• Required books– Machine drawing (Third Edition), Dr. P. Kannaiah,

Prof. K.L. Narayana and Mr. K. Venkata Reddy, New Age International (P) Ltd., Publishers, Published by New Age International (P) Ltd., Publishers, 2006

Chapter one

Introduction to Engineering Graphics

Communication

Development of Engineering Graphics

Multiview DrawingsFrancesca (1420-92)

Cartesian CoordinatesDescartes (1596-1650).

Product Data Management(Solid Work)

Production Lifecycle

Management

Engineering Drawing

Graphic Language

• engineer must have proficiency in– language, both written and oral,– Symbols associated with basic sciences– graphic language.

Irrespective of language barriers, the drawings can be effectively used in other countries, in addition to the country where they are prepared. Thus, the engineering drawing is the universal language of all engineers.

Graphic Language

• Importance of graphic language – Build new structures– Create new machines– Representing the existing ones.

Without engineering drawing, it would have been impossible to produce objects

An engineer should posses good knowledge, not only in preparing a correct drawing but also to read the drawing correctly.

Classification of Drawing

• Machine drawing

Classification of Drawing

• Production drawing

Classification of Drawing

• Part drawing

Classification of Drawing

• Assembly drawing

Classification of Drawing

• Detailed drawing

Classification of Drawing

• Subassembly drawing

Classification of Drawing

• Installation assembly drawing

Classification of Drawing

• Installation for catalog drawing

Classification of Drawing

• Assembly for instruction manual drawing

• Tabular DrawingsClassification of Drawing

Classification of Drawing

• Exploded assembly drawing

Classification of Drawing

• Schematic assembly drawing

Classification of Drawing

• Machine shop drawing

Classification of Drawing

• Patent drawing

Chapter two

Principle of Drawing

Drawing sheet -Sheet Size

A0

A1

A2

A3A4

A5

A4

• Sheet size

Drawing sheet-Sheet Size

Drawing sheet- Sheet Size

• The basic principles involved in arriving at the sizes of drawing sheets are:– X : Y = 1 : – Example : A4 210:297 = 1:

Drawing sheet-Title block

• The title block should lie within the drawing space

• Containing the identification of the drawing• Location is at the bottom right hand corner.

Drawing sheet-Title block

• The title block can have a maximum length of 170 mm.

• providing the following information:– Title of the drawing– Sheet number– Scale– Symbol, denoting the method of projection– Name of the firm– Initials of staff drawn, checked and approved.

Drawing sheet-Title block

Drawing sheet-Title block

PHAROS UNIVERSITY , FACULTY OF ENGINEERING

TITLE:

SCALE:

NAME:ROLL NO:

PLATE NO:EVALUATED BY

110 75

20

10

15

10

10

To be used in all drawings

Power Screw

Studentinstructor Exe Sheet # Example 001

1:2DATE : 28/9/2013

ID # / SEC #

Drawing sheet-Title block

100m

m

10

20 mm

Drawing sheet-Title block

• SCALE 1 : 1 for full size,• SCALE × : 1 for enlarged scales,• SCALE 1 : × for reduced scales.

Drawing sheet-Line

Drawing sheet-Line-application

Drawing sheet-Line-application

Drawing sheet-Line-application

• Order of Priority of Coinciding Lines

Drawing sheet-Line-application

• Order of Priority of Coinciding Lines

Drawing sheet-Line-application

• Leader lines A leader is a line referring to a feature (dimension, object, outline, etc.).

– Leader lines should terminate with :• with a dot, if they end within the outlines of an object• with an arrow head, if they end on the outline of an

object• without dot or arrow head, if they end on a dimension

line

Drawing sheet-Line-application

Balloons containing part numbers.

Leader lines point to the corresponding part.

Balloons are placed in orderly horizontal or vertical rows.

The leader lines; - should not cross, - be as parallel as possible.

Sketching, Text, and Visualization

Examples of Sketches:

Multiview Sketch

Examples of Sketches:

Pictorial Sketch

NOTE: There are also “technical sketches” used in industry which may include notes, and several versions that show motion.

Sketches use “proportion”, not scale!

Proportion allows the designer to use approximate values to create a balanced looking object.

Sketches are…accurate freehand drawings which use single lines to represent edges and features.

Multi-line sketching is NOT used in engineering design. (Scribbling!)

Question!How do you know when a sketch or CAD drawing is complete?

ANSWER: When the production people can make the part without having to ask you any questions!

Most drawings not only have views of the object, but also we include written notes and dimensions to aid in its production.

Projection types:

Drawings use various types of projection (how we view the object), to enhance our ability to visualize what we are being asked to see or understand.

Let’s look at the various styles of projection used…

Projection types:

Here’s how the same object may look using different projection styles.

Projection types:

Projection type is defined by the “line of sight” from the observer.

Let’s look at some of these…..

Perspective:

The line of sight is cone-shaped - which makes objects far away appear smaller to our view. Objects are not “true shape and size”.

Parallel:

The line of sight is always parallel regardless of how far away the object is from our view. This allows surfaces to be drawn “true shape and size”.

Orthographic:

Ortho means “at 90 degrees”, and is a form of parallel projection.

Orthographic projections are used to show several views of the same object in one drawing set.

Orthographic:

The “principle views “ should be chosen to show the most detail of the object with the least number of hidden lines.

Here, the TOP, FRONT, and RIGHT SIDE were chosen.

Understanding what Center Lines do…

Center lines show the theoretical perfect center of arcs, holes, and cylinders. They can be used to show symmetry, or used to aid in dimensioning an object.

Center lines NEVER start or stop on another line!

Steps in creating a 3-view sketch…

Step 1:

Layout the 3 principle views you have chosen with even margins between views and the outside border of your drawing area.

Step 2:

Rough out the general shape of each view.

Steps in creating a 3-view sketch…

Step 3:

Transfer any data from one view to its neighbor using “reverse construction”. This can be done by using a “miter line”.

Step 4:

Add hidden and center lines to the necessary views.

Steps in creating a 3-view sketch…

Step 5:

Erase all unnecessary lines and “snap” the lines on your views.

“Snapping” adds weight to the lines in each view and makes the drawing easier to read.

Step 6:

Add notes and/or dimensions to complete your drawing.

Here’s some tips on creating a multi-view drawing:

1. Lightly sketch all the information that you know first.

2. Use reverse construction to locate lines that may be

unknown such as compound angles.

3. Add all circles and other arcs to your drawing.

4. Snap all arcs and circles first, and then straight lines.

Tutorials Rules

Engineering Drawing Tools

Sketching Assignments