Engineering Drawing First Edition

First Edition 2020 (Ogos)
Copyright of Politeknik Port Dickson

All Right Reserved

Publisher:
Politeknik Port Dickson

KM14, Jalan Pantai,
71050 Si Rusa,
Negeri Sembilan

ENGINEERING DRAWING course provides the students with the fundamentals of
technical drawings. It emphasizes on the practical knowledge of drawing instruments
and drawing techniques. Students shall be able to demonstrate competency in using

some standard available features of technical drawing in engineering drawing.

e-ISBN NO:
978 - 9767 - 2246 - 47 - 3

© Politeknik Port Dickson 2020
i

ENGINEERING DRAWING
1ST EDITION

Published by Politeknik Port Dickson, KM14 Jalan Pantai, 71050 Si Rusa, Port Dickson,
Negeri Sembilan Darul Khursus, Malaysia. Copyright © 2020 by Politeknik Port Dickson.
All reserved. Any part of the book a retrieval system or transmitted, in any form or
manners, whether electronic, mechanic, mechanical, photocopying, recording or
otherwise, without prior permission from the author.

EDITOR
MUHAMMAD HILMI BIN ZAID

MAIN WRITER
MUHAMMAD HILMI BIN ZAID
SITI HAJAR BINTI MOHD NOH
MOHD SHAHRIL FAHMI BIN MOHD ZAINI

GRAPHIC DESIGNER
MUHAMMAD HILMI BIN ZAID

© Politeknik Port Dickson 2020
ii

CONTENTS 1
18
Chapter 1 Introduction To Technical Drawing 48
Chapter 2 Geometrical Drawing 64
Chapter 3 Orthographic Projection and Isometric 75
Chapter 4 Geometric Dimensioning and Tolerance 84
Chapter 5 Sectional View
References

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ENGINEERING DRAWING
Chapter 1.0 Introduction to Technical Drawing
Purpose and Types of Technical Drawing
In some situations, communications will be sufficiently taken care of by use of plain text.
However, in other situations, text alone may not suffice and a more specialized form of
communication (technical/engineering drawing) may prove irreplaceably useful. Drawing
(just like photography) is one of the basic forms of visual communication. Drawing is used
to record objects and actions of everyday life in an easily recognizable manner.
Technical drawings are graphic and technical communication tools. Early humans felt a
need to represent the world (hunting scenes) to their peers. The appearance of
technology gradually led humans to develop another use for drawing. It became a way to
convey technical thought (Archimedes, Leonardo da Vinci). The industrial revolution gave
rise to graphic and communication tools, which facilitated the exchange of technical
information between individuals. An international organization codified some of these
graphic tools so that everyone could understand them.
There are two types of drawings. The first is a drawing done without instruments, known
as a sketch. The second is a drawing done with instruments, known as a final drawing.

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ENGINEERING DRAWING

Technical drawings are the common language of those who work in technology.
Engineers, architects, designers, technologists, technicians and specialized workers use
them to communicate with each other. This universal language varies little from one
country to another. Unlike spoken languages, it ensures unequivocal understanding of
the definition and construction of technical objects. This means that two engineers who
do not speak the same language can understand most of a technical drawing, with the
exception of annotations written in a specific language. Technical drawing is an essential
tool for young people learning about technology. They need to learn the basics through
the tasks assigned to them.

There are two major types of drawings: Technical Drawings
Artistic Drawings

These are a form of freehand These are detailed drawings drawn
representation that makes use of accurately and precisely.
pictures to provide a general impression

of the object being drawn.

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ENGINEERING DRAWING

There are no hard rules or standards in They are pictures that have been
the preparation of artistic drawings. prepared with the aid of mathematical
instruments in order to record and transmit
They are simply drawn by artists, based
more or less on one’s talent and skills. technical information.
They provide an exact and complete
description of things that are to be built or

manufactured.

Although these drawings are often very Technical drawings do not portray the
attractive, they find very limited use in objects the way they directly appear to the

the world of science. eye

They make use of many specialized
symbols and conventions in order to
transmit technical information clearly and

exactly.

There are many types of technical drawings, including:

i. 3D drawings (isometric, perspective)
ii. Exploded-view 3D drawings
iii. Complete working drawings
iv. Detail drawings (2D orthogonal projections)
v. Diagrams are another form of technical drawing with looser, less universal

standards.

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ENGINEERING DRAWING

Engineering Drawing Instruments
Drawing tools may be used for measurement and layout of drawings, or to improve the
consistency and speed of creation of standard drawing elements. Tools such as pens and
pencils mark the drawing medium. Other tools such as straight edges, assist the operator
in drawing straight lines.
Following are the basic instruments used in technical drawing:

1. Pencil

a. Traditional and typical styling used for technical drawing are pencils and

technical pens.

b. Pencils in use are usually mechanical pencils with a standard lead

thickness. The usual line widths are 0.18 mm, 0.25 mm, 0.5 mm and 0.7

mm.

c. Hardness varies usually from HB to 2H. Softer lead gives a better contrast,

but harder lead gives a more accurate line.

Grade of Pencil Hardness of Pencil

9H Hardest

6H, 5H, 4H Extremely Hard

3H Very hard

2H Hard

H Moderately hard

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ENGINEERING DRAWING

F Firm
HB Medium hard
B Moderately soft and black
2B Soft and black
3B Very soft and black
4B, 5B, 6B Very soft and very black
7B
Softest

d. Out of the above 18 grades of pencils, following grades are used in

engineering drawings.

Grade of Pencil Used to Draw

3H Construction lines

2H Dimension lines, center lines, sectional lines, hidden lines

H Object lines, lettering

HB Dimensioning, boundary lines

2. Drawing board

a. Paper will be attached and kept straight and still, so that the drawing can be
done with accuracy.
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ENGINEERING DRAWING
b. The drawing board is usually mounted to a floor pedestal in which the board

turns to a different position, and also its height can be adjustable.
c. Paper could also be secured to the drawing board with drawing pins or even

C-clamps. More recent practice is to use self-adhesive tape to secure paper
to the board.
d. Some drawing boards are magnetized, allowing paper to be held down by
long steel strips.
3. T-Square

a. T square is used to draw horizontal and vertical lines on drawing sheet. It
made of wood or plastic and in T shape. The vertical part of T is called as
blade and horizontal part of T is called as head.

b. The edge of head is uniform level and attached to the edge of the board.
The working edge is used to draw lines anywhere on the sheet by moving
the instrument top to bottom.

4. French Curves

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ENGINEERING DRAWING
a. A French curve is a drawing aid with many different smoothly-varying

radiuses curves on it; the manual drafter can fit the French curve to some
known reference points and draw a smooth curved line between them.
b. French curves are made of wood, plastic or celluloid.
c. Some set squares also have these curves cut in the middle.
d. French curves are used for drawing curves which cannot be drawn with
compasses.
e. A faint freehand curve is first drawn through the known points; the longest
possible curve that coincides exactly with the freehand curve is then found
out from the French curves. Finally, a neat continuous curve is drawn with
the aid of the French curves.

5. Rulers

a. Rulers used in technical drawing are usually made of polystyrene.
b. It is used for drawing lines and connecting points.
c. Rulers come in two types according to the design of their edge.
d. A ruler with a straight edge can be used with lead pencils and felt pens,

whereas when a technical pen is used the edge must be grooved to prevent
the spread of the ink.

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ENGINEERING DRAWING

6. Compass

a. Compasses are used for drawing circles or arc segments of circles.
b. One form has two straight legs joined by a hinge; one leg has a sharp pivot

point and the other has a holder for a technical pen or pencil.
c. Another form, the beam compass, has the pivot point and pen holder joined

by a trammel bar, useful when drawing very large radius arcs.
d. Often a circle template is used instead of a compass when predefined circle

sizes are required.

7. Divider

a. The divider looks like a compass, but the difference is the two legs of divider

are provided with needles.

b. This is used to divide a line or curve into equal parts. It is also used to check

the measurements.

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ENGINEERING DRAWING

8. Eraser

a. Eraser is used to remove the lines or spots which drawn by mistake or with
wrong measurements.

b. The eraser used should be of good quality and soft. It should not damage
the paper while erasing.

9. Templates

a. Templates contain pre-dimensioned holes in the right scale to accurately
draw a symbol or sign.

b. For drawing circles and circle-arcs, circle templates which contain a set of
suitably-sized holes are used.

c. Templates are also available for other geometric shapes such as squares
and for drawing ellipses, as well as many specialized varieties for other
purposes.

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ENGINEERING DRAWING

10. Protractor

a. Protractor is used to draw and measure the angles of lines in the drawing.
It is transparent and made of plastic.

b. It is in the shape of semi-circle, and the edge of semi-circle part consists
reading with one-degree accuracy.

c. The bottom line joins the 0o to the 180o. The center of this bottom line is
marked as “O” or “C” from which the angles are measured.

11. Set square

a. Set squares are used to draw lines with an angle between them. In most of
the structures, 30, 45, 60 and 90-degree lines are most common. So, set
squares make the work easier for this type of drawings.

b. Generally, set squares are of two types. One is 45 degree set square and
another one is called as 30 – 60 degree set square. Both are required in the
drawing. 45 set square has a side of 25 cm while 30-60 set square has 25
cm length on one side.

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ENGINEERING DRAWING

12. Drawing Sheet

a. Drawing sheet is a white paper on which an object is drawn which is
available in various sizes.

b. The sheet used for engineering should be of good quality.
c. It should be white in color with uniform thickness with must resist the easy

torn of paper.
d. The surface of sheet must be smooth.
e. Various sizes of drawing sheets recommended by ISO standards are listed

below:
Drawing Sheet Type Dimensions (Length X Width) (mm)
A0 841 X 1189
A1 594 X 841
A2 420 X 594
A3 297 X 420
A4 210 X 297
A5 148 X 210

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ENGINEERING DRAWING

Standard in Technical Drawing

Standards are set at different levels. There are local standards, national standards,
regional standards and international standards. Typical examples of the different levels
of standards may include;

i. Local Standards: SUA formats for writing various academic reports, Morogoro
Municipal standards for waste disposal, grading of product quality in an industry,
etc.

ii. National Standards: All TBS standards, standards set by local professional bodies
e.g. the Engineers’ Registration Board (ERB), DIN (German), BS (U.K.), GOST
(U.S.S.R.), etc.

iii. Regional Standards: Standards set for the East African Community, standards for
the SADC region, even the AU can set standards for her member states, etc.

iv. International Standards: ISO (International Organization for Standardization)
DIN – an internationally accepted German national standard
BS – an internationally accepted British national standard

It is always desirable to adhere to international standards, particularly the ISO standards
that employ SI units.

Standardization serves five main objectives;

i. Creation of uniform terminology
ii. Maintenance of a limited order of variety
iii. Specification of functional uses and limitations
iv. Establishment of unambiguous objective test methods and material specification
v. Conduction of comparative studies of various standards

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ENGINEERING DRAWING
Scale
Scale is a geometric concept used mainly to represent an object that is too big or bulky
to be drawn to size on a sheet of paper. Drawing to scale means copying an object
proportionally. For example, the 5-cm broken straight line AB below has been reduced by
5 using a reduction constant of 1/5.

Other practical examples include maps, whose scale is 1/10 000 and read so that one
centimeter on the map equals 10 000 cm or 100 m of distance.

Reduction factor: 1:2 1:5 1:10 1:20
Enlargement factor: 2:1 5:1 10:1

Lettering and Numbering
Technical lettering is the process of forming letters, numerals, and other characters in
technical drawing. It is used to describe, or provide detailed specifications for, an object.
With the goals of legibility and uniformity, styles are standardized and lettering ability has
little relationship to normal writing ability. Engineering drawings use a Gothic sans-serif
script, formed by a series of short strokes. Lower case letters are rare in most drawings
of machines.

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ENGINEERING DRAWING
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ENGINEERING DRAWING
Basic Mechanical Drawing Symbol in Engineering
Example of basic symbol in Welding:

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ENGINEERING DRAWING
Example of basic symbol in Machining:

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ENGINEERING DRAWING
EXERCISE

1. Take a piece of paper, write the alphabet from A to Z and numbering from 0 to 9
by using technical lettering as follow:

2. What is the use of scales in engineering drawing?
3. What are different types of pencil grades? Write their uses.

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ENGINEERING DRAWING
Chapter 2.0 Geometrical Drawing
Types of Line and Thickness
The use of different line styles and widths is important in technical drawings as they are
used to indicate details and features of the drawing. Line styles make drawings easier to
read where for example, solid lines used to show the object will stand out from dashed
lines used to show hidden features. The four main types of lines used in drawings are
listed in the table:

Title Block
Standard layouts of drawing sheets are specified by the various standards
organizations. The figure shows the layout of a typical sheet, showing the drawing
frame, a typical title block, parts list (bill of materials) and revision table.

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ENGINEERING DRAWING

The title block is normally placed in the bottom right of the drawing frame, and it
should contain the following information:

i. the name of the company or organization
ii. the title of the drawing
iii. the drawing number, which is generally a unique filing identifier
iv. the scale
v. the drawing size
vi. the angle of projection used, either first or third, generally

shown symbolically
vii. the signature or initials of the draftsman, checker, approving officer, and

issuing officer, with the respective dates
viii. the material of the part
ix. the revision number

x. the sheet number for multi-sheet drawings
xi. other information as required (tolerances, surface finish, etc.)

In addition to the information above, for drawings produced using CAD software, it
is highly recommended to have the following information in the title block:

i. the name of the CAD software used and its version
ii. the name of the drawing file
iii. the name of the source part or assembly file
iv. the units of the dimensions (if the drawing is mistakenly printed on a different

paper size, the scale becomes meaningless)

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ENGINEERING DRAWING
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ENGINEERING DRAWING

Construct 30° Angle by Using Technical Drawing Instruments

After doing this Your work should look like this
1. Draw a line segment which will
become one side of the angle. (Skip this
step if you are given this line.) The exact
length is not important. Label it PQ. P
will be the angle's vertex.
2. Set the compasses on P, and set its
width to any convenient setting.

3. Draw an arc across PQ and up over
above the point P. Label the point where
it crosses PQ as point S.

4. Without changing the compasses'
width, move the compasses to the point
S. Draw a broad arc that crosses the
first one and goes well to the right. Label
the point where the two arcs cross as
point T.

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ENGINEERING DRAWING

5. Without changing the compasses'
width, move the compasses to the point
T, and draw an arc across the previous
arc, creating point R.

6. Draw a line from P to R.

Done. The angle QPR has a measure of
30°

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ENGINEERING DRAWING

Construct 60° Angle by Using Technical Drawing Instruments

After doing this Your work should look like this
1. Draw a line segment which will become one
side of the angle. (Skip this step if you are given
this line.) The exact length is not important. Label
it PQ. P will be the angle's vertex.
2. Set the compasses on P, and set its width to
any convenient setting.

3. Draw an arc across PQ and up over above
the point P.

4. Without changing the compasses' width,
move the compasses to the point where the arc
crosses PQ, and make an arc that crosses the
first one.

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ENGINEERING DRAWING

5. Draw a line from P, through the intersection of
the two arcs.
6. Done. The angle QPR has a measure of 60°

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ENGINEERING DRAWING

Dividing an Angle into Two Equal Part Your work should look like this

After doing this
Start with angle PQR that we will bisect.

1. Place the compasses' point on the
angle's vertex Q.

2. Adjust the compasses to a medium wide
setting. The exact width is not important.

3. Without changing the compasses' width, draw
an arc across each leg of the angle.

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ENGINEERING DRAWING

4. The compasses' width can be changed here if
desired. Recommended: leave it the same.

5. Place the compasses on the point where one
arc crosses a leg and draw an arc in the interior of
the angle.

6. Without changing the compasses setting
repeat for the other leg so that the two arcs cross.

7. Using a straightedge or ruler, draw a line from
the vertex to the point where the arcs cross

Done. This is the bisector of the angle ∠PQR.

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ENGINEERING DRAWING

Construct Right Angle (90°) Your work should look like this

After doing this
Start with a ray with endpoint C. The right
angle will have C as its vertex.

1. Mark a point, not on the given line,
about 6 cm in from C. Its exact location is
not important. Label it D.

2. Set the compasses on point D and set
their width to the endpoint C .

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ENGINEERING DRAWING

3. Draw an arc that crosses the given
line and extends over and above the
endpoint C. (If you prefer, draw a
complete circle.)

4. Draw a diameter through D from the
point where the arc crosses the given
line, creating points B and A.

5. Draw a line from C to the endpoint A
of the diameter line.
Done. The angle ACB is a right angle (90
deg).

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ENGINEERING DRAWING

Constructing an Equilateral Triangle Your work should look like this

After doing this
Start with the line segment AB
which is the length of the sides
of the desired equilateral
triangle.

1. Pick a point P that will be
one vertex of the finished
triangle.

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ENGINEERING DRAWING

2. Place the point of the
compasses on the point A and
set its drawing end to point B.
The compasses are now set to
the length of the sides of the
finished triangle. Do not change
it from now on.

3. With the compasses' point on
P, make two arcs, each roughly
where the other two vertices of
the triangle will be.

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ENGINEERING DRAWING

4. On one of the arcs, mark a
point Q that will be a second
vertex of the triangle. It does not
matter which arc you pick, or
where on the arc you draw the
point.

5. Place the compasses' point
on Q and draw an arc that
crosses the other arc, creating
point R.

6. Using the straightedge, draw
three lines linking the points P,Q
and R.

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ENGINEERING DRAWING

Constructing a Square Given Side Length Your work should look like this

After doing this
We start with a given line segment AB> This
will become one side of the square.

1. Extend the line AB to the right.

2. Set the compasses on B and any
convenient width. Scribe an arc on each
side of B, creating the two points F and G.

3. With the compasses on G and any
convenient width, draw an arc above the
point B.

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ENGINEERING DRAWING

4. Without changing the compasses' width,
place the compasses on F and draw an arc
above B, crossing the previous arc, and
creating point H

5. Draw a line from B through H.
This line is perpendicular to AB, so the angle
ABH is a right angle (90°);
This will become the second side of the
square

6. Set the compasses on A and set its width
to AB. This width will be held unchanged as
we create the square's other three sides.

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ENGINEERING DRAWING

7. Draw an arc above point A.

8. Without changing the width, move the
compasses to point B. Draw an arc across
BH creating point C - a vertex of the square.

9. Without changing the width, move the
compasses to C. Draw an arc to the left of C
across the exiting arc, creating point D - a
vertex of the square.

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ENGINEERING DRAWING

10. Draw the lines CD and AD. Done.
ABCD is a square where each side has a
length AB

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ENGINEERING DRAWING

Constructing a Hexagon Inscribed in a Circle

After doing this Your work should look like this
We start with the given circle, center O.

1. Mark a point anywhere on the circle. This will
be the first vertex of the hexagon.

2. Set the compasses on this point and set the
width of the compasses to the center of the circle.
The compasses are now set to the radius of the
circle

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ENGINEERING DRAWING

3. Make an arc across the circle. This will be the
next vertex of the hexagon.
(It turns out that the side length of a hexagon is
equal to its circumradius - the distance from the
center to a vertex).

4. Move the compasses on to the next vertex and
draw another arc. This is the third vertex of the
hexagon.

5. Continue in this way until you have all six
vertices.

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ENGINEERING DRAWING

6. Draw a line between each successive pairs of
vertices, for a total of six lines.
Done. These lines form a regular hexagon
inscribed in the given circle.

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ENGINEERING DRAWING

Constructing a Pentagon Inscribed in a Circle

After doing this Your work should look like this
We start with the given circle,
center O.

1. Draw a diameter of the circle
through the center point and mark
its endpoints C and M. It does not
have to be vertical.

2. Construct a perpendicular to
CM at the point O.

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ENGINEERING DRAWING

3. Mark the point S where it
crosses the circle.

4. Find the midpoint L of the
segment SO by constructing its
perpendicular bisector.

5. Set the compasses on L, adjust
its width to S or O, and draw a
circle.

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ENGINEERING DRAWING

6. Draw a line from M, through L
so it crosses the small circle in two
places. Label them N and P.

7. Set the compasses on M and
adjust its width to P.

8. Draw a broad arc that crosses
the given circle in two places.
Label them A and E.

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ENGINEERING DRAWING

9. Set the compasses on M and
adjust its width to N.

10. Draw a broad arc that crosses
the given circle in two places.
Label them B and D.

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ENGINEERING DRAWING

11. Draw a line from A to B, then
B to C etc, until you have drawn all
five sides of the pentagon.

Done. ABCDE is a regular
pentagon inscribed in the given
circle.

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ENGINEERING DRAWING

Drawing an Ellipse with String and Pins Your work should look like this

After doing this
Start with the height and width of the desired
ellipse. The two lines are the major and
minor axes of the ellipse. The major axis is
the longer one.

1. With the compasses' point on the center,
set the compasses' width to half the width
(major axis) of the desired ellipse.
(This is called the ellipse semi major axis).

2. Move the compasses' point to one end of
the minor axis of the desired ellipse and
draw two arcs across the major axis.

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ENGINEERING DRAWING

3. Where these arcs cross the major axis
are the foci of the ellipse. Label them F1, F2.

4. Put a pin in each end of the major axis
(they will be moved later), and tie a string to
them so that the string between them is taut.
The best way to do this is to push the pin
through the string itself if possible, rather
than tying a knot.

5. Leaving the string attached, move the
pins to the focus points F1, F2. Put a pencil
point against the string and pull the string
taut with the pencil.

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ENGINEERING DRAWING

6. Keeping the string taut, move the pencil in
a large arc. The pencil will draw out the
desired ellipse. To avoid the string catching
on the pins, you may find it better to draw the
upper and lower halves of the ellipse
separately.
7. Done. The ellipse will pass through the
four initial points defining the ends of the
major and minor axes.

46