Engineering Drawing- Complete

8/12/2019 Engineering Drawing- Complete

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Engineering DrawingConducted By:

T.L.Lau


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Module Purpose

To equip the Trainees with the knowledge andskills in producing Mechanical Drawings usingDrawing Board and Drafting Instruments sothat Drawings are produced according toStandard Specification

To enable the Trainees to apply the principlesof Geometrical Construction in producingvarious Geometrical drawings

To enable the Trainees to apply the Principlesof Orthographic Projection in producingvarious First and Third Angle Projection of anobject.

To be able to Construct Pictorial (Isometric)Drawings from the Orthographic Projectionsgiven and vise-versa.


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Course Outline

Topic 1

Drawing Equipments and materials

Topic 2

Geometrical Construction

Topic 3

First and Third Angle Orthographic

Projections

Topic 4Isometric Projection


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Topic 11. Drawing Equipments

i) The Drawing Board


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ii. Set Squares

A. The 45 Triangle

and

B. The 30 - 60

Triangle


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iii. Instrument Set

The BOFA Set


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a. Correct Usage of Instruments

i. The Compass

a) Flat side of lead faces outside;


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b. Practice correct method of

sharpening the lead.


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c. Avoid sharpening lead

on the side facing the

needle;

d. Avoid usingconical points


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f. Put pressure on the metal point to prevent

compass from jumping out of the centrehole.


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BEFORE WE PROCEED

FURTHER

See whether you can answer the

following short questions.


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Questions

i. Technical drawings are produced

by a drafter using drawinginstruments.

True False


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ii. Industrial or technical drawings

and prints are made for the purpose of______________ .

a. Reading;

b. Communication;

c. Showing off;

d. Self Satisfaction


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iii. Currently, with the wide usage of IT, most

of the technical drawings are done using

Microsoft software.

True False


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NOW WE CAN PROCEED


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2. DRAFTING MATERIALSa. Paper Sizes

ISO Standard Paper Sizes:-

SIZE

DIMENSIONS

A

A1

A2

A3

A4

A5

A6

841 X 1188

594 X 841

42 X 594

297 X 42

21 X 297

145 X 21

1 5 X 145


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b. TYPES OF PENCILS USED

Type Alines show the outline of the feature of an object. They are the thickestlines on a drawing and done with a pencil softer than HB.

Type Blines are dimension lines and are used for dimensioning, projecting,

extending, or leaders. A harder pencil should be used, such as a 2H.

Type Clines are used for breaks when the whole object is not shown. Theyare freehand drawn and only for short breaks. 2H pencil

Type Dlines are similar to Type C, except they are zigzagged and only for

longer breaks. 2H pencil

Type Elines indicate hidden outlines of internal features of an object. They aredotted lines. 2H pencil


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(CONTINUE.)

Type Flines are Type F[typo]lines, except they are used for drawingsin electrotechnology. 2H pencil

Type Glines are used for centre lines. They are dotted lines, but a longline of 1020mm, then a gap, then a small line of 2mm. 2H

pencil

Type Hlines are the same as Type G, except that every second long line isthicker. They indicate the cutting plane of an object. 2H pencil

Type Klines indicate the alternate positions of an object and the line taken bythat object. They are drawn with a long line of 1020mm, then a small

gap, then a small line of 2mm, then a gap, then another small line. 2H

pencil.


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3. Standard Drawing Practices

A. How to begin your drawing

B. The Dos

C. The DONTs


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A. How to begin your drawing

1. Clean the drawing board and allthe drawing instruments using

hand-kerchief, napkin or a

piece of clean cloth.


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2. Fix the drawing sheet over a padding

sheet on the drawing board;


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3. Draw the border lines using HB

pencil; standard spacing is 10 mm.and 15 mm on bottom.


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4. Prepare a suitable Title Block

Example


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C. The DONTs1. Never use cheap quality pencil and eraser.

2. Always use divider for transferring measurementsfrom the scale to the drawing.

3. Never put either end of pencil into your mouth.

4. Never sharpen pencils over the drawing board orsheet.

5. The sliding rule or mini drafter and set squaresmust be cleaned properly every time.

6. Never keep the drawing instruments like

compasses and dividers outside the instrumentbox while not in use.


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Questions

1. What is the correct A3 size of drawingpaper according to the International

Standard Organization?420 mm x 297 mm.

2. What is the first thing you should do when

you want to start technical drawing?Clean the drawing board and all thedrawing instruments.


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TOPIC 2GEOMETRICAL CONSTRUCTION

1. Layout of Drawings Planning must be done before starting a drawing

to ensure a balance and pleasant layout.

Example:


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2. Lines And Angles

1. To Divide a line into

equal parts.

2. To Bisect a Line.


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3. To Bisect an Angle

4. To Construct

Perpendiculars


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5. To Construct Angles

and bisect them.

6. To Copy an angle


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7. To Construct

Triangles.

8. a) Inscribed and c) Circumscribed Circle

b) Escribed Circle


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9. To Construct Polygons.

10. To construct Tangents and Circles


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11. Geometrical Construction Practice


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Lesson Feedback

Any explanation on GeometricalConstruction that you do not fully

understand?


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If there is no more question..

Lets continue with TOPIC 3

ORTHOGRAPHIC PROJECTION


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TOPIC 3ORTHOGRAPHIC PROJECTION

What is Orthographic Projection?

Answer :

a. It is a Multiple view drawing showing flatrepresentations of a principle object.

b. It is the also the most accurate method of

shape description of an object


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Answer:

a. The object is represented by looking at it fromdifferent directions reproducing them in a flattransparent, but imaginary projection plane.

The most basic method is to project the object intothree views, the Plan or Top View, the Front View

and the Side View.

Q: How is it done?


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Three basic views of an object


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1. First Angle Projection

1. Third Angle Projection

There are two main methods

of Projection:


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Can use a maximum of SEVEN

projections if more details are

needed from an object


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Details of abbreviations used


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Engineering Drawing- Complete

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