CGT 164: Graphics for Civil

Engineering and construction

Lecture 2: Basic Principles OF Engineering

Drawings
Lecture Content
1. Drawing standards
❑ Line standards
❑ Letter standards
❑ Paper size and layout standards
2. Drawing Scales
3. Drawing Instruments and Instrument Drawings Hints
Drawing Standards
▪ Engineering drawings communicate how to manufacture or construct a product, system or device.

▪ In order to clearly describe this information, technical drawings adhere closely to formal standarts
▪ Drawing Standards: sets of rules that govern how parts are made and technical drawings are represented.
- Line standards

- Letter standards

- Paper size and layout standards

https://www.bluentcad.ca/blog/shop-drawings-vs-construction-drawings-vs-as-built-drawings/
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Drawing Standards
▪ Engineering drawings communicate how to manufacture or construct a product, system or device.

Country Code Full name

USA ANSI American National Standard Institute

Japan JIS Japanese Industrial Standard
UK BS British Standard
Australia AS Australian Standard
Germany DIN Deutsches Institut für Normung

ISO International Standards Organization

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Drawing Standards: Line Standards
Line Standards in Engineering Drawings (Developed by ASME: American Society of Mechanical Engineers):
¬ Visible line
¬ Hidden line
¬ Center line Improper drawing
All lines are drawn with
¬ Dimension line, Extension line and Leader same style
¬ Section line / Hatching
¬ Cutting plane and Viewing plane lines
¬ Short break line Proper drawing
¬ Long break line Lines that can be seen are
drawn with visible line style,
¬ Phantom line lines that cannot be seen
¬ Chain line drawn with hidden line style

• The meaning of each line on a technical drawing is indicated by its particular line style and its width.
• The preferred width of the lines depends on the paper size, but the width ratio of lines with respect to each
other is constant.
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Drawing Standards: Line Standards
Visible line
Thick - Continuous
Represents features that can be seen in the
current view

Hidden line
Thin – Dash
Represent features that can not be seen in the
current view

Center line
Thin – Dash
Represents symmetry, path of motion, centers
of circles, axis of axi symmetrical parts etc.

Important notes for centerline:

Center lines do not end with short line segments (not necessarily end with 19mm, but must be longer than 3mm)! Extend them to exceed corresponding shape slightly!

✓ Center lines are exceeding the visible lines of the

drawing slightly
✓ Center lines end with long line segments

✓ Intersection of two short line segments represents a

point. In that case, it reprpesents the center of circle!
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Drawing Standards: Line Standards

Dimension line, Extension line, Leader

Thin – Continuous
Iindicates the sizes and location of features on
a drawing
Extension line must have small gap with
the visible line

Section line / Hatching line

Thin – Continuous
Used for hatching the surfaces that section
plane intersects

Cutting Plane Line & Viewing Plane Line

Thick – Dashed
Cutting plane lines indicate a plane or planes in
which a sectional view is taken
Viewing plane lines are used to indicate the
plane or planes from which a surface or several
surfaces are viewed.

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Drawing Standards: Line Standards

Short-break line
Thick – Continuous & Free form
Used for visualizing partial sections

Long-break line
Thin – Continuous & Free form
Used for reducing the size of long objects that
continuous in the same manner.

Phantom line
Thin – Dash
Used for showing repeated detail
Used for showing alternate position of moving
parts

Chain line
Thick – Dash
Used for showing lines or surfaces to which a
special requirement applies

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Drawing Standards: Line Standards

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Drawing Standards: Line Standards

Center line Center line Center line Center line

(as axis of circle) Center line
Center line
Center line Center line
(as axis of cylinder)

Center line

Center line
Center line Center line

Center line
Phantom line

Center line
Center line
Center line

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Drawing Standards: Line Standards

A1 Visible lines
B2 Dimension lines
B5 Section/Hatching lines
D1 Long break lines
G1 Center lines as axis of circle
G2 Center lines as lines of symmetry
G3 Center lines as path of motion
E1 Hidden lines
K2 Phantom lines
J1 Chain lines

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Drawing Standards: Lettering Standards
* There are several lettering styles in technical drawing.

* CAD drawing, Font: MS Gothic or Roman

* Inclined letters have 68o slope from the horizontal. In the

drawings, you can use either vertical or Inclined letters and
numbers, but you must have consistent lettering type within the
drawing (do not use both at the same time). Similar rule is applied
also for the Font in CAD drawing, select either Gothic or Roman.

* 0.5 – HB pencil will be used for letters in hand drawings.

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Drawing Standards: Layout Standards

▪ Trimmed paper of A4
a size A0 ~ A4.
A3

▪ Standard sheet size (ANSI)

A2
A4 210 x 297
A3 297 x 420
A2 420 x 594 A1

A1 594 x 841
A0 841 x 1189
(Dimensions in millimeters)

A0

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Drawing Standards: Layout Standards
▪ Orientation of drawing sheet

1. Type X (A0~A4) 2. Type Y (A4 only)

c
d
d c Drawing
Border Drawing space
space Title block
lines Title block
c

Sheet size c (min) d (min)

A4 10 25
A3 10 25
A2 10 25
A1 20 25
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A0 20 25
Drawing Standards: Layout Standards

Start Reading Engineering Drawings

View Paper Size Scale

(Angle)

1:2
Title Block

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Drawing Standards: Layout Standards
▪ Title Block
Layout Standards – Title Block
* The title block is located in the lower right corner of the format. Below is a representative example for a title block.

UNLESS OTHERWISE SPECIFIED:

ALL DIMENSIONS ARE IN DECIMAL MM
AMERICAN UNIVERSITY OF 1

12 MIDDLE EAST
2
CLUTCH HOUSING
11 DRAWN BY: MURAT KARA
SIZE DWG NO. GRADE 3
CONTROLLED BY: E. TOLGA DURAN CLASS WORK 1
A2 85
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DATE: 09.06.2019 SCALE 1:1 MATERIAL: GRAY CAST IRON SHEET 1 OF 3

9 8 5
7 6 4

1 University Name, Letters have 6mm height, 0.5-HB 7 Scale, Letters have 3mm height, 0.5-HB
2 Drawing Title, Letters have 6mm height, 0.5-HB 8 Paper size, Letters have 3mm height, 0.5-HB
3 Grade, Letters have 3mm height, 0.5-HB 9 Date, Letters have 3mm height, 0.5-HB
4 Sheet number, Letters have 3mm height, 0.5-HB 10 Name of the controller, Letters have 3mm height, 0.5-HB
5 Material definition, Letters have 3mm height, 0.5-HB 11 Name of the drafter, Letters have 3mm height, 0.5-HB
6 Drawing no, Letters have 3mm height, 0.5-HB 12 Notes, Letters have 3mm height, 0.5-HB
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Drawing Scales

Length, size
Scale is the ratio of the linear dimension of an element
of an object shown in the drawing to the real linear
dimension of the same element of the object.

Size in drawing Actual size

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Drawing Scales

▪ Designation of a scale consists of the word “SCALE” followed by the indication of its
ratio, as follow: SCALE 1:1 for full size
SCALE X:1 for enlargement scales (X > 1)
SCALE 1:X for reduction scales (X > 1)
▪ Dimension numbers shown in the drawing are correspond to “true size” of the
object and they are independent of the scale used in creating that drawing.

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Drawing Scales

▪ Recommended Scales

▪ Intermediate scales can be used in exceptional cases where

recommended scales can not be applied for functional reasons
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Drawing Scales
Start Reading Engineering Drawings

Familiarize yourself with Understand the basic symbols Identify specific abbreviations
the scale of the drawings used in the drawings e.g. DIA, which stands for diameter

Look for circled numbers Understand projection Which side is facing you?
Circled numbers indicate critical dimensions or the techniques
area shown in greater detail on another page
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Instrument Drawing Hints

Instrument Drawing Hints – Drawing Straight Lines

* Assure full contact of your pencil
lead and T-square/ruler for the sake
of drawing proper and straight lines. ~60o

* Uniformity of line widths and weights

can be achieved by holding the pencil
approximately 60 degrees from the
drafting surface.

* Do not slide your T-square or rulers over the drawn area since it may cause your drawn lines to be
dispersed.

* The lead caused dirt can accumulate on your rulers and T-square, which may cause your drawing
area to be blackened. It is suggested to clean your rulers and T-square with a piece of tissue when
necessary.

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Instrument Drawing Hints

Instrument Drawing Hints – Drawing Vertical Lines

Set your triangle on T-square/Ruler by

using it as a reference, press the
straight edge of the T-square/Ruler and
triangle with one hand and move the
pencil with the other hand.

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Instrument Drawing Hints

Instrument Drawing Hints – Drawing Angular Lines with Triangles

* Angular lines having 15o, 30o, 45o, 60o, 75o
can be drawn by using triangles together with
T-square/Ruler.
* It is similar to drawing a vertical line, but
you should set your triangle properly.

All angles made with All angles made with

standard 45o triangle standard 30o-60o triangle

23 15o angles 75o angles

Instrument Drawing Hints

Instrument Drawing Hints – Drawing Angular Lines / Step 1

Step 1
Mark the starting point of the angular line (not
as big as shown in the figure, this is only for
illustration. Normally, those points can not
be observed (means no bigger than the
weight of line).

Locate your protactor’s origin on this point

while setting it on T-square/Ruler at the
same time.

Mark the point for the angle to be generated.

Step 2
Remove the T-square/Ruler and the protractor,
locate your ruler between those points.

Draw the angular line.

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Instrument Drawing Hints

Instrument Drawing Hints – Drawing Angular Lines / Step 2

Step 1
Mark the starting point of the angular line (not
as big as shown in the figure, this is only for
illustration. Normally, those points can not
be observed (means no bigger than the
weight of line).

Locate your protactor’s origin on this point

while setting it on T-square/Ruler at the
same time.

Mark the point for the angle to be generated.

Step 2
Remove the T-square/Ruler and the protractor,
locate your ruler between those points.

Draw the angular line.

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Instrument Drawing Hints

Instrument Drawing Hints – Drawing Parallel Lines

Parallel horizontal lines can be drawn Parallel vertical lines can be drawn by
by simply sliding the T-square! simply sliding the triangle!

Parallel angular lines can be drawn by

simply sliding the triangle!

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Instrument Drawing Hints

Instrument Drawing Hints – Drawing a Circle

Dimensions given:

Location of the center point

Lightly mark your center point.

By using T-square/Ruler, draw the horizontal center axis line with 0.3-2H.

Set your triangle on T-square/Ruler and draw the vertical center axis
line with 0.3 – 2H. Intersecting short portions of axis lines forms a cross
which designates a “point”. For circle, it represents “the center point of
the circle”.

Set your compass to circle radius, and then locate the metal tip to the
Note: Reference points that are lightly marked center point.
are used to help to construct the
geometry, they do not exist/can not be
Rotate the compass to draw the cirlce.
observed in the final drawing.

27 Circle template can be used instead of compass!

Instrument Drawing Hints

Instrument Drawing Hints – Drawing a Triangle

Given: Length of sides of the triangle

C Draw the one side of the triangle (A to B) by using your

T-square/Ruler.

Set your compass to the length of side (BC) and draw

an arc having the center point at B.

Repeat the previous step for the last side of the triangle
(AC) and draw an arc having the center point of A.
A
B The intersection of two arcs generates the point C.

Draw the lines of (AC) and (BC) by using your ruler.

Note: Arcs are used for determining the location

of point C and they are not the part of final
drawing. Draw them lightly and delete after
locating your point C.

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Instrument Drawing Hints
Instrument Drawing Hints – Drawing an Arc Tangent to the Right Angle
Given: Perpendicular lines
Radius of the arc, R

Draw lines parallel to lines A and B. Locate your parallel lines

at a distance of arc radius. Use your T-square and
A R triangle while
constructing those lines.
The intersection point of those parallel lines gives the origin of
the arc.
O Draw your center lines for circle axes.
Set your compass to arc radius, draw an arc originated at point
O and
R tangent to the lines which have 90o angle.
R

C B Note: The center of the arc can be found by

measuring R from corner C of
perpendicular lines, and drawing
center lines for circle axes from those
points! Prefer this method in complete
Note: Drawing arcs which are tangent to any angle is
drawings, it avoids drawing of parallel
tracing exactly the same procedure, the only
lines and therefore helps to keep your
difference is the angles between lines A and B.
29 drawing area clean!
Instrument Drawing Hints
Instrument Drawing Hints – Drawing an Arc Tangent to Two Circles, Case 1
Given: Origin and the radii of circles Case A: The upper tangent
Radius of the tangent arc, R

-Draw circles A and B as described in

the previous slides
P
-Draw a circle originated at point A
R+R R+R
and having the radius of RA + R, A
R B

where RA is the radius of circle A and

R is the radius of the tangent arc. A B
-Similarly, draw a circle originated at
point B and having the radius of RB +
R, where RB is the radius of circle B
and R is the radius of the tangent arc.

-The intersection point of those two circles is the origin of tangent arc, P. Set
your compass to arc radius R and draw the tangent arc originated at P, darken
the lines of main drawing and delete the unnecessary lines.
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Instrument Drawing Hints
Instrument Drawing Hints – Drawing an Arc Tangent to Two Circles, Case 2
Given: Origin and the radii of circles Case B: The lower tangent
Radius of the tangent arc, R

-Draw circles A and B as described in

the previous slides

-Draw a circle originated at point A and

having the radius of R-RA, where RA is P
the R-R
radius of circle A and R is the radius of
R-R A
B

the tangent arc.

A B
-Similarly, draw a circle originated at
point B and having the radius of R-RB, R
where RB
is the radius of circle B and R is the
radius of the tangent arc.
-The intersection point of those two circles is the origin of tangent arc, P.
Set your compass to arc radius R and draw the tangent arc originated at P,
darken the lines of main drawing and delete the unnecessary lines.
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