SCHOOL OF RAILWAYS AND
INFRASTRUCTURE DEVELOPMENT
MC/EL/ES/CE/GM/GL 155
TECHNICAL DRAWING
A. A. Afari &
Alhassan Sullaiman
Department of Mechanical Engineering, UMaT
03-Mar-21
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Course Objectives
This course is divided into five chapters and intended to develop the following skills.
Chapter 1 is to:

Identify traditional technical drawing tools and

Learn the proper usage of traditional drawing tools.
Chapter 2 is on

Dimensions
Chapter 3 is on

Simple geometric constructions.
Chapter 4 focuses on more complex constructions:

Cycloidal curves

Involute

Spiral curves and
Chapter 5 is to:

Identify types of projection

Learn to produce Orthographic projections
In Chapter 6 we learn to produce Isometric projections
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Chapter 7 will introduce Computer Graphics (AutoCAD)
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TENTATIVE ASSESSMENT
Class Attendance and Participation
Assignments
Quizzes
End of Semester Exam
TOTAL
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10%
20%
10%
60%
100%
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REFERENCE MATERIALS




Technical Drawing Course Manual, KNUST & UMaT
Bhatt, N.D. and Panchal V.M.; Engineering Drawing.
Parker, M.A. and Pickup, F.; Engineering Drawing I.
Jackson, E and Coll, M. Geometrical and Engineering Drawing.
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Class Regulation
 No lateness to class (not more than 10 mins after stipulated start
time)
 You will not participate in final exams if you miss 30% of class
lectures.
 No use of mobile phones during lecture period until you are told
to do so; it will be confiscated when found guilty.
 Any form of plagiarism is not accepted in all assessments
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INTRODUCTION
TECHNICAL DRAWING
 Technical drawing also known as Engineering graphics is basically a form of information
communication system of which a number of different systems have been developed to facilitate
the communication of both technical and non-technical information including spoken language,
written language, mathematics and graphics.
 Engineering graphics is a visual communications language incorporating text, symbols, images, and
numeric information. It includes everything from the traditional types of engineering drawings to
sophisticated computer models, and all follow the rules or laws of visual science.
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Why Technical Drawing
It is a formal and precise way of communicating information about the
shape, size, features and precision of physical objects.
A universal language of Engineering used in the design process for solving
problems, quickly and accurately visualizing objects, and conducting analysis.
A graphical representation of objects and structures.
It can be done by using freehand, mechanical, or computer methods.
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ASSIGNMENT #1
1. Write the History and Development of Technical/Engineering
drawing. Not more than 2 pages if MS Word processed (Double
spacing, Times New Roman, Font size -12)
2. Produce a drawing of any Product you can see it.
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1 TOOLS AND TECHNIQUES
1.1 INTRODUCTION
Just as graphic language has evolved over the years into sophisticated set of standards and conventions, so
have the tools used to graphically communicate technical ideas. Tools are used to produce three basic
types of drawings:
 Freehand sketches,

Instrument drawings, and

Computer drawings and models.
The tools have evolved from pencils, triangles, scales and compasses to computer-aided design/ drafting
(CAD) systems. Traditional tools are devices used to assist the human hand in making technical drawings.
The assistance includes drawing lines straighter, making circles more circular and increasing the speed and
ease with which drawings are made.
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1.2 TRADITIONAL TOOLS AND LINE DRAWING INSTRUMENTS
1.2.1 TRADITIONAL TECHNICAL DRAWING TOOLS
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1.2.1 TRADITIONAL TECHNICAL DRAWING TOOLS
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DRAWING SHEET
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ISO-A series (mm)
Drawing Field
A0
841x1189
821x1159
A1
594x841
574x811
A2
420x594
400x564
A3
297x420
277x390
A4
210x297
190x267
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TECHNIQUE OF LAYING OUT A DRAWING PAPER
The drawing paper is inserted it the drawing board by press-hold on the rough surface at
the left side of your drawing board. The left and lower sides of the drawing board will be
elevated. Insert the drawing paper and release you hand from the rough surface. The upper
right corner of the paper is also clipped to remove any air space below the drawing paper
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Border lines
Draw the borderlines by measuring 10 mm from the right edge and 10 mm from the top edges of the
drawing paper. Draw vertical line as the right hand border line, and the top horizontal line. Measure
390 mm and 277 mm from the right and top border-lines respective. Draw the left vertical border line
and the lower horizontal border-line.
Title Block
The title block is an important feature in drawing because it gives all the information of the prepared
drawing. It is located at the right hand bottom corner of the drawing paper. See the figure above.
There are several standard title blocks (e.g. ISO, DIN, etc., title blocks) as well as company-specific title
blocks. All title blocks must contain at least the following information:
 Title of drawing

Name of firm

Date and names of the drafter, checker, and designer,

Scale
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The details of the title block for drawings within this course MC/EL/CE/ES/GM/GL 155
are shown below:
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Text (Lettering)
The art of writing the alphabets A, B, ……. ,Z and numbers such as 1, 2, 3,…….0, etc., is known as lettering. It must be neat and legible so that it
can be read easily both on the original drawing and on a reproduction such as a blueprint or photo copy.
Requirement of good lettering:
•The proportion of lettering refers to the relationship between the height, width and spacing of each letter. There are no fixed standards for the
proportions of each letter but the following proportion of lettering are known:
i.
ENGINEERING
NORMAL LETTERING
ii.
ENGINEERING
CONDENSED LETTERING
iii.
ENGINEERING
EXTENDED LETTERING
•The composition (format) of letter into words and words into sentences must be equal to the eye judgment. Upper, lower or mixed cases.
•The spacing of letters is the distance left between two adjacent letters:
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Scale
Scale indicates the ratio of the size of the drawing of a part or machine to its actual size
irrespective of the unit of measurement used.
The following are the sizes of scale which are used in engineering practice:
Magnification (scaled up)
X: 1
Natural
1:1
Reduction (scaled down)
1: X Where X is an integer
Example: 1: X
Will be interpreted as 1 unit of the drawing represent x units of the actual piece.
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LINE TYPES
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General rules in drawing lines
All chain lines should start and finish with a long dash and when thin chain lines are used as center lines
they should cross one another at solid portions of the line. Centre lines should extend only a short distance
beyond the feature unless required for dimensioning or other purposes. They should not extend through the
spaces between views and should not terminate at another line or the drawing. When angles are formed in
chain lines, long dashes should meet at corners. Arcs should join at tangent points. Dashed lines should also
meet at corners and tangent points with dashes.
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1.4 LINE DRAWING TECHNIQUES
Non-Continuous Lines
The continuous lines (line types A, B and C) are easier to draw than the noncontinuous lines (line types D, E, F and G). Whereas the width of continuous lines is
the only characteristics of these lines, the width as well as length of the gap, short
dash and long dash play an important role in differentiating these lines, the length of
these entities depends on the scales (size) of the view. However, the following is
proposed for:
Gap ≈ 1 mm
2 mm ≤ Short dash ≤ 3 mm
15 mm ≤ Long dash ≤ 30 mm
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Horizontal Lines
The Tee square in conjunction with the drawing board (DB) is required for horizontal lines. The useful edge
of the head of the T-square must be pressed against the working edge of the drawing board by means of the
four fingers of the left hand. In order to ensure that the T-square lies on the drawing sheet the left hand
must rest on (presses) the blade. For a right-handed person you draw from left to right with the pencil
inclined at 60º to the surface of the board. A T-square is used for drawing only horizontal lines.
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Vertical Lines
The principal edges of either 60/30 or 45/45 set squares can be used in conjunction with the
T- square to draw vertical lines.
i. Ensure that the edge of the T-square is aligned with the left edge of the drawing board.
ii. Align one edge of the set-square with the top edge of the T-square, and hold both the
set-square and the T-square in position with the left hand.
iii. Draw from bottom to top.
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Perpendicular Lines
Making use of two set squares to draw perpendicular lines involves:
i. Align the edge (not the hypotenuse) of one triangle with the given line.
ii. Align the hypotenuse-edge of the second triangle against the hypotenuse of the first triangle and hold the
second triangle in position.
iii. Slide the first triangle along the edge of the second triangle to the required position and
draw the required perpendicular line.
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Parallel Line
Making use of two set-squares to draw parallel lines involves:
i. Setting up one of the edges of the first triangle to align along the given line.
ii. Align the edge of the second triangle along the base the first triangle
iii. Hold the second triangle in position, and slide the first triangle along the edge of
the second triangle to its new position and draw the parallel line required
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Irregular Curved Lines
French curves are used to draw curves that are neither circles nor arcs. Examples of such curves
are cycloids, parabolas, ellipses, involutes, etc. the nature of the curvature along the edges should
be noted. The process of drawing such curved lines involves:
i. A set of points are used to locate the required curve,
ii. Align a selected French curve so that the edge goes through a minimum of three points.
iii. Draw a line that goes through these points.
iv. Adjust the French curve to go through the next minimum three points (these points
should include the two points). If that particular French curve does not fit the trend of the
curve a different French curve must be selected,
v. Repeat these steps to complete the curve.
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Regular Curved Lines
Circles or arcs are drawn with a pair of compasses. The needle is required to be slightly inserted
inside the paper. Therefore, it must be about 1 mm longer than the lead point (see Fig. 15). The
lead must be about one degree softer than the pencil lead. This is necessary to reduce the
amount of pressure required on the lead to maintain the uniform darkness in all the lines.
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Fig. 15
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How to draw a circle or an arc
i. Draw two perpendicular center lines to mark the center of the circles or arc, and use the scale
to mark the radius along one of these center lines.
ii. Set the compass point at the intersection of the center lines; set the compass to the radius by
aligning the lead point of the compass with the mark on the center line.
iii. Draw the circle or arc leaning the compass in the direction that the circle is to be drawn,
putting most of the pressure on the lead point (see Fig. 16).
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Fig. 16
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END OF CHAPTER 1
ASSIGNMENT 2
EXERCISE 1, PAGE 102
DRAW FROM FIGURE (a-f) USING A SCALE OF 1:1
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