Construction
Manual and Computer-Aided
Construction Drawing
(Higher)
6391
Spring 2000
HIGHER STILL
Construction
Manual and Computer-Aided
Construction Drawing
Higher
Support Materials
Acknowledgements
The Higher Still Development Programme gratefully acknowledges permission
granted by the following copyright owners: Autodesk Inc for screenshots from
Autocad (Release 14), © 1999 Autodesk Inc; British Standards Institution for extract
from BS 1192: Part I: 1984 (Comparison of Projection Methods).
Please note that reference is made throughout this pack to BS1192: Parts 1 to 5 –
Construction drawing practice. This standard is to be progressively replaced over the
next few years by BS EN ISO 4157. BS EN ISO 4157-1: 1999 is now published and
BS1192: Part 1: 1984 is withdrawn. BS EN ISO 4157-1 does not, however, cover the
methods of orthographic projection and reference to BS1192: Part 1 is, therefore,
made in Study Guide 2.
Every attempt has been made to gain permission to use extracts from the appropriate
copyright owners. The Higher Still Development Programme apologises for any
omission which, if notified, it will be pleased to rectify at the earliest opportunity.
CONTENTS
OVERVIEW
TEACHER’S/LECTURER’S GUIDE
STUDENT’S GUIDE
STUDENT’S SUPPORT MATERIAL
Study Guide 1
Basic drawing skills
Study Guide 2
Orthographic projection
Study Guide 3
Construction drawings
Study Guide 4
Computer-Aided construction drawing
Construction: Manual and Computer-Aided Construction Drawing (Higher)
Construction: Manual and Computer-Aided Construction Drawing (Higher)
CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
OVERVIEW
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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Construction: Manual and Computer-Aided Construction Drawing (Higher).
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OVERVIEW
These support materials are provided to assist teachers/lecturers in delivery of the
Higher Construction unit Manual and Computer-Aided Construction Drawing.
The Teacher’s/Lecturer’s Guide offers brief advice on teaching approaches for the
unit and this should be read in conjunction with the Subject Guide for DET
Construction (published by SCCC/HSDU/SFEU 1997).
Guidance is provided on formative and summative assessment and on use of the
National Assessment Bank Support Materials for the unit Manual and ComputerAided Construction Drawing (published by SQA 1999).
Advice is also given on the role of the unit in the development and assessment of core
skills.
The Student’s Guide provides a brief introduction to the unit, offers guidance on
studying the unit and contains details of resources and reference materials. Students
are also directed to the Candidates’ Guide of the National Assessment Bank Support
Materials for information on assessment procedures.
Student’s Support Materials are provided in the form of four Study Guides, each
covering one or two Outcomes of the unit.
Each Study Guide contains the following:
 a statement of the relevant Outcome/s
 an explanation of what the student should be able to do on completion of the
Outcome/s
 learning and teaching materials including worksheets and assignment task sheets.
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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Construction: Manual and Computer-Aided Construction Drawing (Higher).
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
TEACHER’S / LECTURER’S GUIDE
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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Construction: Manual and Computer-Aided Construction Drawing (Higher).
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TEACHER’S/LECTURER’S GUIDE
INTRODUCTION
The unit Manual and Computer-Aided Construction Drawing focuses on the
important role of drawing in the development, communication and interpretation of
construction proposals. The study of presentation techniques used in manual drawing,
along with the more advanced techniques of CAD, will provide useful and
transferable skills for all students of construction.
Many school pupils study the principles of graphical communication, and develop
basic skills in manual drawing. Such students should have little difficulty in
extending their skills to the preparation of construction drawings to acceptable
industry standards. Other students, with no prior experience of manual drawing as a
means of communication, will require more time to develop and practice drawing
skills. The unit is suitable for both groups of students.
TEACHING AND LEARNING
The unit Manual and Computer-Aided Construction Drawing is a component unit of
Higher Construction. As mentioned in the Subject Guide for Higher Construction, the
unit can be used to achieve extensive integration of the three units of the Higher
course. The graphical work for the preparation of general arrangement drawings and
details, required by the unit Building Design, and the preparation of site plans for the
unit Site Surveying 1, may be integrated with the work of the unit Manual and
Computer-Aided Construction Drawing. Such integration will result in a more
relevant and motivating learning experience for students. Concurrent delivery of the
three units is recommended, since this will inject realism into the entire process of
student learning.
A series of Study Guides will be made available, covering a number of aspects of
Higher Construction. The Study Guides in these support materials cover only the unit
Manual and Computer-Aided Construction Drawing, since some students may wish to
study the unit as ‘stand alone’ rather than as part of the Higher Construction course.
Each of the four Study Guides contains learning and teaching materials which
teachers/lecturers may use selectively or in their entirety during delivery of the unit.
Assignment task sheets and worksheets are also provided. The teaching material
covers all the content of the unit but teachers/lecturers will likely add to the material
through the use of local or national case studies and by further examples of completed
sets of drawings for actual construction projects. The Subject Guide stresses that
students learn in different ways and that a variety of teaching approaches is likely to
be required to meet students’ individual needs. The methods used should help
students relate what they learn to practical industrial situations. For the unit Manual
and Computer-Aided Construction Drawing, it is important that the approach be
student centred, because drawing skills will only be developed through drawing board
practise and by completion of a series of formative drawing exercises.
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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STUDY GUIDE 1
This covers much of Outcome 1 and provides an introduction to the use of drawing
instruments, to layout and presentation, and to graphical conventions. The principles
of orthographic presentation, included in Outcome 1, are covered in Study Guide 2.
Six assignment task sheets and a number of worksheets are included, and these may
be used selectively to encourage students to practise basic drawing skills. The six
assignment subjects are:
1.
2.
3.
4.
5.
6.
Line drawing
Use of scale rule
Lettering
Dimensioning of simple shapes
Dimensioning of floor plan
Simple geometric shapes
STUDY GUIDE 2
This covers the orthographic projection content of Outcome 1. The Guide briefly
introduces the range of orthographic and pictorial projection systems available for
construction drawing. The emphasis is on first angle orthographic projection, and the
two assignments included require students to prepare first angle projections of a range
of objects and buildings. The two assignment subjects are:
1. Free-hand first angle orthographic projection
2. Scale and dimensioned first angle orthographic projection.
It is important that students are given adequate time to practise and improve basic
drawing skills in the preparation of orthographic drawings. Teachers/lecturers may
wish to issue further assignments to students with no previous drawing experience.
STUDY GUIDE 3
This covers Outcome 2. It will help students to learn of the range of drawing types
used in construction projects, and help them to develop the ability to prepare site
layouts and general arrangement drawings. After coverage of the main types of
drawing and the scales adopted, examples of drawings are provided to illustrate the
technical communication requirements of each type of drawing. Teachers/lecturers
should make available for inspection, typical sets of drawings for local projects.
The work of Outcome 2 should ideally be integrated with that of Outcome 4 of the
unit Building Design, which requires students to prepare general arrangement
drawings (building location drawings) and large scale details (assembly drawings).
Study Guide 3 for the unit Building Design may be issued along with Study Guide 3
of this unit. The work of Outcome 2 may also be integrated with that of Outcome 2 of
the unit Site Surveying 1, which requires students to prepare a scale site plan of a
surveyed area of land.
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Student activity may be partly based on:
 the National Assessment Bank internal assessment assignments for the unit
Manual and Computer-Aided Construction Drawing
 the National Assessment Bank internal integrated assessment assignment for the
unit Building Design
 the National Assessment Bank internal integrated assessment assignment for the
unit Site Surveying 1
 the external assessment project for Higher Construction.
Teachers/lecturers may wish to issue additional drawing tasks, prior to students
commencing work on the various assignments. This may help students with little or
no experience of drawing.
STUDY GUIDE 4
This covers Outcome 4. It will provide students with the ability to use a twodimensional computer-aided drawing (2D CAD) system to prepare drawings for small
building projects. A brief introduction is provided to the reasons for the increasing
use of CAD systems and the equipment requirements of such systems.
The Subject Guide for Higher Construction recommends that students examine sets of
exemplar CAD drawings for real construction projects and that a visit to a
professional CAD drawing office would serve to stimulate learning.
The support material is based on the use of AutoCAD (Version 14). Other CAD
systems adopt different command access systems. Centres using other systems should
adapt the Study Guide as required.
After an introduction to screen layout, the Guide is divided into 6 sections as follows:
1. Exercises in use of the mouse
2. Editing or modifying drawings
3. Accurate drawing with sizes and angles
4. Adding text or annotation to the drawing
5. Adding dimensions to the drawing
6. Adding hatching to the drawing.
After a brief teacher/lecturer introduction to each section, students should be
encouraged to work through the exercises, carefully following the step by step
instructions. Additional tasks may be issued, to enable students to practise use of
various functions. Student activity may be partly based on the production of drawings
required for the National Assessment Bank assessment for the unit. Drawings
required for the other two units of Higher Construction and for the external
assessment project for the course may also form the basis of further CAD work.
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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ASSESSMENT
Internal unit assessment
The National Assessment Bank support materials for the unit Manual and ComputerAided Construction Drawing contain six instruments of assessment. The first covers
Outcome 1 and is a manual drawing exercise on orthographic projection. Three
instruments of assessment are provided for Outcome 2; a short question paper
covering the types and purposes of construction drawing and two manual drawing
exercises covering the preparation of site layouts and general arrangement drawings.
Two instruments of assessment are provided for Outcome 3; a simple CAD exercise
requiring preparation of an orthographic drawing of the same building as used for
Outcome 1, and a CAD drawing of a site layout.
The question paper is to be used under ‘closed book’ supervised conditions. A
marking scheme is provided. All other graphical exercises may be completed with
access to notes, drawing standards and CAD manuals. A marking schedule and a
series of checklists are provided to assist assessors record candidates’ performance in
each sub-task. It is important to remember that assessors must closely monitor the
graphical exercises to ensure that evidence submitted is the candidates’ own work.
It is recommended that the instruments of assessment be used in the numbered
sequence, since it is preferable that students demonstrate a knowledge of drawing
layout, projection methods and manual drawing techniques prior to developing skills
in the use of CAD.
The National Assessment Bank support materials for the unit provide guidance on the
time, which should be made available for each assessment task. These times allow for
both formative and summative stages.
External course assessment for Higher Construction
The external assessment for Higher Construction will be carried out using:
 A three-hour question paper
 A project devised by the centre, based on an SQA specification. The project will
be internally assessed and externally moderated.
The project specification explains how internal evidence for certain Outcomes may be
gathered from the project mandatory tasks. The result will be to reduce the total
amount of assessment, and teachers/lecturers are advised to read the National
Qualifications Project Specification prior to commencing delivery of the unit Manual
and Computer-Aided Construction Drawing.
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CORE SKILLS
The unit Manual and Computer-Aided Construction Drawing does not carry any
embedded core skills. However, the Subject Guide for the Higher Construction
course includes a supplement, which offers advice on how Information Technology at
Intermediate 2 may be delivered in combination with the units of the course.
Teachers/lecturers are advised to read this supplement along with the support material
for the Scottish Group Awards in Construction, published by SQA.
RECOMMENDED RESOURCES
The Student’s Guide contains a list of textbooks and British Standards which
teachers/lecturers and students may find useful.
Please note that reference is made throughout this pack to BS1192: Parts 1 to 5 –
Construction drawing practice. This standard is to be progressively replaced over the
next few years by BS EN ISO 4157. BS EN ISO 4157-1: 1999 is now published and
BS1192: Part 1: 1984 is withdrawn. BS EN ISO 4157-1 does not, however, cover the
methods of orthographic projection and reference to BS1192: Part 1 is, therefore,
made in Study Guide 2.
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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Construction: Manual and Computer-Aided Construction Drawing (Higher).
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
STUDENT’S GUIDE
Construction: Manual and Computer-Aided Construction Drawing (Higher).
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Construction: Manual and Computer-Aided Construction Drawing (Higher).
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STUDENT’S GUIDE
INTRODUCTION
The graphical communication of construction proposals is an essential part of the
overall design and construction process. The construction industry is currently
working hard to improve the quality of buildings and this requires that the production
drawings, which are to be found on every construction site, are clear and
unambiguous. The problems resulting on site from poor preparation, co-ordination
and issuing of drawings are considered in Study Guide 3 of the support materials for
the unit Building Design. The construction industry has prepared a code of procedure
for the management of the preparation, co-ordination and issuing of production
drawings used in building works. This code is complementary to British Standard
1192 Construction Drawing Practice, which is referred to in the Study Guides for this
unit.
Most professional construction drawing offices now make use of computer-aided
drawing (CAD) systems. The advantages of such systems are considered in Study
Guide 3.
Study of the unit Manual and Computer-Aided Construction Drawing will provide
you with a knowledge of the requirements of construction drawings and will enable
you to develop basic presentation skills in both manual and CAD drawing. The unit
will provide a foundation for more advanced study in the use of CAD systems.
STUDYING THE UNIT
On completion of the unit you will have knowledge of the types and requirements of
construction drawings. It is important, however, that you approach study of the unit
with the intention of developing your own skills in manual drawing board work and in
the use of CAD. To achieve this aim, you will have to work on your own, in the
classroom and possibly at home, to develop and practise the techniques of
presentation. Your teacher/lecturer will be available to offer guidance and advice and
to point out areas in which you need to improve. Spend time working on your own,
but don’t forget to ask for help if you find a particular task or technique difficult.
Often a simple change in the way you hold an item of equipment, such as a pencil or a
set square, can result in dramatic improvement.
To assist you in learning, a series of Study Guides will be made available. Each will
contain the following:
 a statement of the relevant Outcome/s
 an explanation of what you should be able to do on completion of the Outcome/s
 learning materials including assignment task sheets and worksheets.
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ASSESSMENT
You are encouraged to read the Candidates’ Guide, which forms part of the National
Assessment Bank material for the unit Manual and Computer-Aided Construction
Drawing. This explains how assessment of the unit will be carried out. The
assessments used will be based on realistic industry drawing exercises. You will
make mistakes in the early drawing work but your teacher/lecturer will provide
feedback on your progress at regular intervals. View completion of the assessment
exercises as an important part of your learning.
CORE SKILLS
The CAD assessment tasks of the unit will also assist you to develop the core skill of
Information Technology. Successful completion of the Higher course in Construction
will result in automatic certification of other core skill components, and successful
completion of a Scottish Group Award at Higher will lead to certification of further
components. You should be aware of the evidence you must gather to demonstrate
attainment of core skills and your tutor will guide you in this area.
RECOMMENDED RESOURCES
You will find it helpful to refer to a textbook on construction drawing. The following
books are recommended:
Architectural Graphics, by Francis D. K. Ching. Published by Van Nostrand
Reinhold.
Working Drawing Handbook, by Keith Styles. Published by Architectural Press.
Reekie’s Architectural Drawing, by Fraser Reekie. Published by Edward Arnold.
An Introduction to Construction Drawing, by Arthur Thompson. Published by
Edward Arnold.
Beginning with AutoCAD, by Bob McFarlane. Published by Edward Arnold.
Drawing Practice Manual, published by the Building Research Establishment.
BRE Digest 172, published by the Building Research Establishment
The British Standards publications covering construction drawings are:
BS 1192: Parts 1 to 5 and PG - Construction drawing practice.
PP7319: 1989 - Construction drawing practice for universities, polytechnics and
colleges.
PP7320: 1988 - Construction drawing practice for schools.
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
STUDY GUIDE 1
Basic drawing skills
Construction: Manual and Computer-Aided Construction Drawing (Higher). Study Guide 1
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Construction: Manual and Computer-Aided Construction Drawing (Higher). Study Guide 1
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STUDY GUIDE 1: BASIC DRAWING SKILLS
INTRODUCTION
Outcome 1
Utilise basic drawing skills in the production of drawings.
On completion of this Outcome you should be able to:
 correctly select and use a range of drawing instruments and materials
 accurately draw lines and shapes to different scales
 neatly letter, annotate and dimension drawings
 use the graphic conventions commonly adopted in construction drawing.
This Study Guide is designed to help you to develop the basic manual drawing skills
required in construction drawing. The material is suitable for students with little or no
experience of drawing board work. You may, however, already have studied
graphical communication and have acquired certain basic skills. The Guide will
encourage you to practise such skills and extend them to the preparation of
construction drawings to an acceptable industry standard.
Included in the Study Guide are a number of assignment sheets, which will allow you
to gain experience in the correct use of instruments and graphic conventions.
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EQUIPMENT AND MATERIALS
This section illustrates the types of drawing equipment and materials used in
construction drawing. The equipment considered is commonly used in architectural,
civil engineering and building services drawing offices for the manual preparation of
drawings.
Pencils
Pencils are extensively used in drawing and are very familiar to all students. However
there is more to choosing the correct pencil for a drawing task than might first be
realised.
Grades of pencil
Pencils are available ranging from 9H (extremely hard) to 6B (extremely soft).
The type of paper to be drawn on affects the grade of pencil to be used – the rougher
the paper the harder the lead which should be used. In drawing offices the main type
of paper for finished drawings is tracing paper but rougher detail paper is often used
for roughing-out the drawing. Different grades of pencil may be used on each type of
paper.
The most important reason for using different grades of pencil is the effect that
hardness can have on the finished drawing.
4H
hard and dense
for accurate layouts
not for finished drawings – good for very light construction lines
do not use with a heavy hand as this grooves the paper and may not
erase easily
does not print well
2H
medium-hard
hardest grade feasible for finished drawings
does not erase easily if used heavily
F and H
medium
excellent general purpose lead weight
for layouts, finished drawings and lettering
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HB
soft
for dense, bold linework and lettering
requires control for fine work
erases easily
prints well
tends to smear easily
B-range pencils
these tend to smear too easily for use with T-square and set-squares but
can be used to shade areas of the drawing to give effects.
Drawing on tracing paper allows offices to make copies on a photographic process
called Dyeline Printing. In this process the tracing paper is placed over a
photosensitive paper and run through an intense light which burns off the blank areas
and leaves the lines and shaded areas. Different densities of lines and shading show up
on the finished developed print. Many effects can be achieved by using various grades
of pencil, ink, colours, felt pens etc.
Aids to drawing straight lines
T-squares
These are used to draw all horizontal lines and to support the other pieces of
equipment used to draw angled lines. If the T-square is kept in good condition the
lines drawn will always be parallel and horizontal. The detachable T-square can be
used to draw sloping lines over the length of the drawing which can be useful in the
case of perspective drawing or large elevations which may require sloping ground
lines. The fixed T-square or Parallel Action is found on many office drawing boards.
Edge of
Drawing Board
Clear plastic drawing edge (use one side only)
Keep T-square
Tight to edge of
Drawing Board
Do not draw too close to end
of the T-square as it may bend
Typical T-square
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Set squares
These are clear plastic triangles with set angles.
There are two types:
1
45 Set squares -
where the angles are 45 degrees and 90 degrees.
2
30/60 Set squares -
where the angles are 30 degrees, 60 degrees and 90
degrees
200 - 250mm
These squares can be used to create a number of set angles in combination and sitting
on the T-square.
Use of T-squares and set squares to draw lines
Having drawn a few good horizontal lines, pass on to the use of set-squares and the
drawing of vertical and inclined lines Take the 45-degree set-square or the closed
adjustable set-square and with this practise drawing lines, as shown in the figure. One
edge of the set-square rests on the blade of the T-square and is held- in position-where
required by the left-hand, which also holds the T-square firm. Lines are drawn with
the pencil- along the other edges of the set-square in the directions indicated by the
arrows. A number of parallel lines should be drawn bearing in mind the precautions
mentioned above.
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Fig 1 Horizontal
Fig 2 Vertical and 45
Fig 3 Vertical 30 and 60
Fig 4 15 and 75
The 60-degree set-square- or the adjustable set-square set to this angle can be used
similarly, as shown for vertical lines and lines at 60 degrees and 30 degrees to the
horizontal.
By a combination of 45-degree and 60-degree set-squares it is possible to draw lines
at 15 degrees and 75 degrees to the horizontal, as shown in the figure. This is worth
trying a few times for practice, as there are three things to manipulate with the left
hand; but it is seldom necessary to use this method, and the advantages of the
adjustable set-square- which can be set to these and any angle in such cases is
obvious.
When a number of lines are to be drawn parallel to an inclined line as may occur inthe setting-out of roofing, etc. the following method could be used. Place a set-square
along the inclined line so that another of its edges is at right-angles to the line. Then
gently-bring up the T-square until it is against this edge of the set-square, hold it
tightly and then, by moving the set-square along the T-square to the required
positions, lines parallel to the first one can be drawn. This method should be practised
with lines at varying angles.
Remember in all cases to keep the pencil well sharpened and held properly against the
ruling edge.
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Adjustable Set Square
This is useful for drawing any angle.
Scales
Scales are thin narrow strips of white or yellow plastic, or boxwood or ivory, with
divisions along each edge usually on both sides. These divisions are in various
recognised proportions to actual distances and dimensions, and can therefore be used
for making new drawings ‘to scale’ or for measuring, by ‘scaling’, (as it is termed)
existing drawings.
The two sides of the R.I.B.A. Approved Scale for metric drawings are shown
overleaf. This is the scale now commonly used by architects. There are two lines of
divisions along each edge in. the proportions of 1:10/1:100, 1:20/1:200, 1:5/1:5O,
1:25/1:2500.
Other kinds of scales are available for land survey and town planning drawings.
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Typical Scale Rules RIBA Approved
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Paper sizes
The advantages of standardised sizes for drawings are that they enable a more
economical use of drawing and tracing paper, sensitised paper and cloth for prints,
etc., to be made, and that the binding together and storing of the drawings becomes
easier.
Standardisation is almost automatic when ‘A’ sizes are used and sheets of different
size can be folded to a common size for filing in folders, for example Al sheet as
illustrated.
Drawings for transmission by post or for loose storage can be similarly folded. In all
cases the title block appears uppermost for ready reference.
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LINE DRAWING AND SCALES
This section covers one of the most important aspects of good technical drawing, that
is, the production of good quality lines of the correct weight and to the correct size.
Line weight
Line weight helps to convey meaning to a technical drawing.
 Important objects in the drawing can be highlighted by using heavier lines.
 In Elevations the objects nearer to the viewer can be shown darker to make them
appear closer.
 Grid lines can be drawn faintly so as not to overcrowd the rest of the drawing.
 Dimension lines can be drawn in very fine line.
All of the above help to give the drawing a more professional look as well as making
the important parts stand out. There are no hard and fast rules as to the actual weight
of lines to be used in each situation but the draughtsperson is left to apply judgement
as to what would be suitable. In this respect a technical drawing becomes as much a
graphical illustration as purely a factual drawing.
Typical line weights showing pencil used and appropriate situation
Typical architectural elevation
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Line types
There are a number of situations in a Construction drawing where line weight is not
enough to distinguish between different parts of the drawing.




When different services or utilities, (gas, water, electricity) have to be shown on
the same plan.
When different materials are used
Where hidden lines need to be shown
Where centre lines or grid lines are shown
In these situations it is common to use different line types to distinguish between
them.
Colour is not an option in most cases as the final prints of drawings will usually be in
grey-scale only.
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Line quality
Line quality refers to:
 Crispness and clarity
 Blackness and density; and
 appropriate weight.
While inked lines vary only in width, pencil lines can vary in both value and width.
Thus a pencil line’s weight is controlled by the density of the lead used (affected by
grade of lead, drawing surface, humidity) as well as the pressure with which you
draw.
It is essential that you understand as you draw what each line represents whether it is
an edge, an intersection of two planes or simply a change in material or texture.
All lines should start and end definitely; always touching at their ends, always bearing
a logical relationship to other lines from beginning to end.
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Drawing to scale
Construction drawing more often than not involves objects of considerable size. This
means that a normal sized drawing board will not be able to accommodate the object
drawn full size.
The draughtsperson must decide the following factors before arriving at a scale to use:
 How much detail needs to be shown
 What is the actual size of the object to be drawn
 What size of paper would be most appropriate
 What is the normal convention for the type of drawing being produced.
The following are recommended scales for use with the metric system.
Use
Scale
Ratio
Maps
1:1000000
1:500000
1:200000
1:100000
1:50000
l mm to l000m
l mm to 500m
l mm to 200m
l mm to 100m
l mm to 50m
Town surveys
1:50000
1:20000
1:10000
1:5000
1:2500
1 mm to 50m
l mm to 20m
l mm to l0m
l mm to 5m
1 mm to 2.5 m
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Use
Scale
Ratio
Survey and layouts
1 :2500
1:2000
1:1250
1:1000
1:500
1 mm to 2.5 m
l mm to 2m
l mm to l25m
l mm to lm
l mm to 0.5m
Site and key plans
1:1250
1:1000
1:500
1 mm to 1.25m
l mm to lm
l mm to 0.5m
Sketch schemes, etc.
1:200
1:100
1 mm to 0.2 m
l mm to 0.lm
Location drawings
1:200
1:100
1:50
1 mm to 0.2 m
l mm to 0.lm
l mm to 0.05m
Component and
assembly detail
drawings
1:20
1:10
1:5
1:1
1 mm to 0.02 m
1 mm to 0.01m
1 mm to 0.005m
Fullsize
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Complete Assignments Nos. 1 and 2
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Construction: Manual and Computer-Aided Construction Drawing (Higher). Study Guide 1
Vertical Lines at 6mm spacing
Draw the lines as shown on A3 paper trying to maintain the spacing throughout and keeping the line density constant.
45 Inclined Lines at 6mm spacing
Horizontal Lines at 6mm spacing
STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 1 – Line drawing
17
STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 2 – Use of scale rule.
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LETTERING AND DIMENSIONING
This section covers other, important aspects of good technical drawing – adding
notation text or lettering and dimensions to a drawing.
Lettering a drawing
The lines on a drawing are very important indeed but without some text to explain
what the lines are the drawing would be of little use. Text is also used extensively in
Construction drawing to give details of the materials and the types of construction,
often called the Specification.
The process of adding text or notation to a drawing is called Lettering.
For normal drawing board work the usual lettering technique is called Hand Lettering.
This involves very little if any assistance to the draughtsperson but relies only on the
skill and expertise of that person.
There are many aids to lettering but all have their problems and special skills which
must be learned before good results are produced. Some of these aids are mentioned
for information but Hand Lettering is preferred as a good style produces an individual
drawing which has the stamp of the person who drew it. (Some offices do not want
individuality in their drawings and so insist on a particular aid being used on all
drawings).
Stencils
These are available in a variety of sizes and styles but can only be used with ink and
must be used with care. It is very difficult to prevent blotting of the ink and correct
spacing of the letters and words is quite difficult. The correct thickness of pen is
essential to produce acceptable stencilled lettering.
Press-on transfers
These can be used but have great problems in spacing and lining up.
Lettering machines
These are like very small computers which can have the notation typed in then the
machine is placed on the required spot and set to print on to the drawing. These
produce very good lettering but tend to look too clinical. They are also very
expensive.
Typing to film
With this technique the notation is typed on to special clear film by a skilled typist.
The film is then stuck on to the drawing in the required position. This technique is
good as long as the film is very clear and does not cause a darker area round the
notation. There is no doubt that this technique provides a good way of adding large
volumes of type to a drawing such as in a specification.
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General points on lettering
Size
should be determined on the basis of:
1.
readability from the observer’s point of view; and
2.
the proportional relationship of the lettering to the overall size and
scale of the drawing.
Weight
is determined by the size and value (ranging from white through a
series of grays to black) of the letters; i.e., if a large-sized typeface is
required for readability from a certain distance, but a low value is
mandatory for a balanced composition then an outline letter should be
used.
Placement
of titles should be determined on the basis of their overall weight or
tonal value and their role in the organisation of the presentation.
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HAND LETTERING
Complete Assignment No 3
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STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 3 – Lettering
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Dimensioning
Dimensions are extremely important on drawings as it should never be necessary to
scale sizes from copies of the drawing. The drawing will have been done to accurate
scale but the copying process could distort the sizes and give false readings.
Dimensions should be easy to read but not dominate the lines of the drawing. This is
quite difficult to achieve in practice but with care the minimum of dimensions will
give the maximum information.
The dimension lines should be the faintest possible and should be well enough away
from the objects so as not to interfere with them. The lettering size should be carefully
chosen to be clear but not too prominent.
Some indications of good dimensioning style are given below but the actual layout
will depend on the draughtsperson or the standard office style.
Gap between
extension line
and object
Dimension line
Extension line
Alternative ways to
show termination.
Tick
Extension line should
extend past dim. line
Dim. line should
extend past ext. line
Typical Simple Dimensioning
Complete Assignment Nos. 4 and 5
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STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 4 – Dimensioning of simple shapes.
Fix this sheet to your drawing board and dimension the shapes.
Assume the shapes are drawn at 1:20 scale
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STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 5 – Dimensioning of floor plan.
Floor Plan at 1:100 Scale
Fix this sheet to your drawing board and dimension the drawing :Measure the sizes and dimension the outside perimeter of the building.
Measure the sizes and dimension the top part of the plan along the line
shown.
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DRAWING SIMPLE GEOMETRIC SHAPES
This section covers the drawing of simple geometric shapes. Drawings consist of
various simple geometric shapes arranged in such a way as to create other complex
shapes. Often these complex shapes are again combined and so a complex drawing is
made up from the very simple shapes such as line, arcs, circles, rectangles and
triangles.
Squares
Squares are simply regular rectangles with all sides equal and all angles right angles.
This means that there are a number of ways in which a square can be drawn. In
construction drawing it is essential that sizes are drawn accurately and so it is
recommended that all sizes should be measured individually. This does not mean that
using compasses, dividers and 450 set square should not be done but that their use
should be carefully controlled.
D
C
D
C
Draw AB along T-square to correct length
Draw a line up fro B using th right angle
on a set square to same correct length to C
Draw a line back from C the same correct length to D
A line drawn from D with the set square should meet
A at exactly the correct length.
A
Draw AB along T-square to correct length
Draw a line up fro B using th right angle
on a set square
Draw a line from A using the 45 set square
C is where the 45 line meets the line fom B
Construct point D in the same way using point B to start
B
A
B
C
D
C
Draw a line along the T-square from A
Set the correct length of the sides on compasses
Place the point on A and cut an arc on the line for point B
Draw a line up from B using a set square
Place the compass point on B and cut the line for point C
Continue from C for point D
A
B
B
D
Draw a line from A using a 45 set square
Measure the correct length fro A to B
Use the 45 set square to set up line B to C
Continue from C to D in the same way
A line at 45 down from D should meet A at exactly the correct length
A
There are many combinations of ways to draw all shapes and the methods shown
above can be modified to suit conditions.
Rectangles
These are four sided figures with all the internal angles being right angles. They can
be constructed in similar ways to Squares.
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Rhomboids
These are four sided figures which are parallelograms (opposite sides parallel) but in
this case they do not have any right angles.
C
D
A
B
The lengths of the sides and one angle must be known to draw these shapes.
Draw side A to B using the T-square and measure the length.
Set off the side AD to the known angle and measure the correct length.
From D draw a line parallel to AB (in this case with the T-square).
From B draw a line parallel to AD.
The intersection of the two lines gives point C.
Triangles
These are three sided figures.
Drawing of a triangle requires:
 the sizes of the three sides
 the sizes of two sides and the included angle
 the sizes of the angles and one side.
Special triangles are worth mentioning as they may be encountered in many drawings.
Equilateral triangles
These have three equal sides and three equal angles, each angle being 60 degrees.
Isosceles triangles
These have two equal sides and two equal angles.
Right angled triangles
These have two sides at right angles to each other.
Scalene triangles
These have unequal sides and unequal angles.
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Drawing Triangles
C
C
A
Equilateral Triangle
Draw line AB the required length
Set the length AB on compasses
Place the point on A and draw an arc
Do the same with an arc from B
Where they intersect is point C.
Draw line AB the required length
Set the length of the equal sides on compasses
Place the point on A and draw an arc
Do the same with an arc from B
Where they intersect is point C.
The 60 set square can also be used by
drawing 60 lines from A and B and using
the intersection for point C
If the equal angles are known then draw lines at
these angles from A and B to get
the intersection for point C
B
A
C
B
Isosceles Triangle
C
Draw line AB the required length
Drwa a line up at right angles to A
Measure the length AC on this line
Join the points to form the triangle.
B
A
Right angled Triangle
Draw line AB the required length
Set the length of the side AC on compasses
Place the point on A and draw an arc
Do the same with an arc of length BC from B
Where they intersect is point C.
A
B
ScaleneTriangle
Circles
Circles, Arcs (parts of circles) and other related shapes such as Ellipses form
important parts of drawings even though a lot of shapes in construction, especially in
buildings are straight lines.
It is useful to have a knowledge of the terms used in relation to circles and curves.
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Useful Techniques in all Drawings
It is often necessary to perform some construction work on the drawing before a final
shape can be achieved. The techniques required for these can best be illustrated by the
following exercises which will look at:
 Bisecting angles
 Filleting
 Joining lines and curves (same technique as filleting)
 Dividing lines
 Drawing ellipses.
Bisecting an angle
1
Two lines with and unknown angle between
2
Strike an arc with compasses at any distance through each line.
3
Strike an arc from each intersection point on the line
to meet each other as shown.
4
Draw the bisector line as the line from where the
arcs meet to the intersection of the two lines
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Filleting a curve between two lines
parallel lines
5
1
Use the technique above to
bisect the angle.
2
Draw a line parallel to one of the lines
at a distance equal to the fillet radius.
3
Extend the new parallel line
to cross the bisector line.
4
Draw a circle to the required radius
using this crossing as the centre.
The circle should just touch the lines and no more.
Darken in the required parts of the
lines and circle and erase the rest
to leave the fillet and lines.
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Dividing lines
1
Draw a line of any length and then
draw a line from one end at any angle.
3
2
Measure up the angled line, equal distances
of any length and on any scale.
Join the point which marks the last division
with the end of the first line.
Draw lines parallel to this new line,
from the marks on the angled line
down to the first line.
The first line will now be divided into the
same number of equal divisions
as the angled line.
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Ellipses
As with most shapes there are a number of ways to draw an ellipse. The method
shown uses the two axes of the ellipse, the Major and Minor, to construct circles then
radiating lines from the centre to get co-ordinates on to the circumference of the
ellipse. The more radiating lines which are used the smoother the ellipse can be drawn
as the drawing will be free-hand.
3 Lines drawn from centre
out to major axis
1 Major Axis
4 Lines drawn vertically
down from major axis
intersection
2 Minor Axis
5 Lines drawn horizontally
across from minor axis
intersection
6 Ellipse is drawn free-hand
to join the points.
The more points the
smoother the ellipse.
Drawing an Ellipse
Complete Assignment No 6
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STUDY GUIDE 1: BASIC DRAWING SKILLS
Assignment No 6 – Simple geometric shapes.
46mm
46
m
m
m
46mm
m
46
76mm
80
66m
mm
46mm
23mm
45°
SQUARES
m
RHOMBOID
70mm
SCALENE
TRIANGLE
160mm
Arc Radius = 25mm
DIVISION OF A LINE
Line divided into 7 sections
100mm
m
m
50mm
5
R4
ELLIPSE
CIRCLE
Draw the shapes shown to the sizes given.
Dimension the shapes as shown and add
the text under each shape.
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SYMBOLS AND BORDERS
This section covers the graphic conventions used to represent materials and standard
objects in construction drawing. It also covers the means of finishing drawings
through the addition of borders and titles.
Graphical Symbols
These are useful shortcuts to adding information to drawings. Many features are
standard on all drawings and are represented on the drawing by symbols which should
be those recommended in BS 1192.
The symbols generally take up less space on the drawing than the actual object and so
do not tend to obscure other important features. They should be large enough to be
located easily and be recognisable.
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Typical Electrical Symbols Used on Services Floor Plans
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Typical Plumbing and Drainage Symbols Used on Services Plans
and Site Layout Plans
Typical Water, Gas, Heating and Ventilating Symbols Used on Services Plans
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Typical Symbols or Hatching used in construction drawing to distinguish
between materials.
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Borders
Borders fulfil two functions namely:
1. They frame and enclose the drawing giving it a finished appearance.
2. They provide an area of paper round the edge of the drawing which might become
damaged without affecting the information on the drawing.
BS 1192 recommends that borders are placed in such a way that important
information about the drawing and the project will be visible when the drawing is
folded for storage or posting. This usually means that a title box is incorporated in the
border and is best placed at the right edge of the drawing usually at the bottom of the
paper.
Most professional offices have a standard layout for borders and title blocks which
usually has a space for the office title, name of the project, drawing number, drawing
title, scale, date, responsible person and any other information thought appropriate. It
is also common to have space above the title box to list and date amendments to the
drawing. Many offices have their drawing sheets pre-printed showing all the
information to save drawing it on every time.
The BS recommendation is often not appropriate for student drawings as the paper
size is often limited and such a border and title box takes up too much space.
Extract from BS 1192 showing possible positions for title boxes in borders
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
STUDY GUIDE 2
Orthographic projection
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STUDY GUIDE 2: ORTHOGRAPHIC PROJECTION
INTRODUCTION
Outcome 1
Utilise basic drawing skills in the production of drawings.
On completion of this Outcome you should:
 know the range of orthographic and pictorial projection systems used for
construction drawing
 be able to correctly apply the principles of orthographic projection in the
preparation of construction drawings.
Included in the Study Guide are two assignment sheets, which allow you to practise
drawing first angle projections of a range of shapes and buildings.
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ORTHOGRAPHIC DRAWING
This section deals with the range of parallel projection systems available and the
method of producing orthographic projections of three dimensional objects and
buildings.
Parallel projection systems
Orthographic Drawings
Buildings and the materials and components of which buildings are constructed, are
three dimensional. That is to say they have length, width and height.
It is possible to produce drawings which show all three dimensions and these are
useful in picturing either the completed design for the Client, or for showing a
complicated assembly to the Contractor. However it is most common to show
information in two dimensions with different views giving the complete picture.
The views used are called:
 Plans
 Sections, and
 Elevations.
Study Guide 3 shows examples of these.
The amount of detailed information required and, to a certain extent, the intended user
of the drawing, dictates the scale to which the drawing is prepared.
Plan
A plan is generally a view of a building or object looking down on it.
In the case of floor plans, the roof or upper floors are removed to
show the walls of the floor in question.
Section
A section is a view of a building or object obtained by making an
imaginary cut through it. A horizontal cut through produces a
horizontal section. A vertical cut through produces a vertical section.
Elevation
An elevation is a view you get if you look in a horizontal direction at
the vertical sides or faces of a building or object. All heights are
drawn to correct sizes as if every part of the elevation was seen from
straight ahead. (This is unlike a three dimensional representation such
as a perspective view where objects further away from the viewer
appear smaller).
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The British Standard for Construction Drawing Practice is BS 1192.
It is in five (5) parts:
Part 1
Part 2
Part 3
Part 4
Part 5
Recommendations for general principles
Recommendations for architectural and engineering drawings
Recommendations for symbols and other graphic conventions
Recommendations for landscape drawings
Guide for structuring of computer graphic information
The recommendations on drawing practice in this unit are based on BS 1192, although
there are considerably more points in the BS than are contained here. Students
wishing to progress further may find it useful to refer to BS 1192 for more
information.
BS 1192 will, over the next few years, be progressively replaced be BS EN ISO 4157,
part 1 of which is now published.
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Extract from BS 1192 Part 1 showing the range of parallel projections available.
Note that the first column Orthographic is the range of projections we are considering.
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In practice the projections recommended in the BS are often not possible. Drawings
showing plans, elevations and sections on one sheet would either have to be on very
large sheets, be to very small scale or be of very small objects.
Construction drawing tends to be concerned with large objects such as buildings and
they must be shown in reasonable detail on paper sizes which are easy to handle on
site. For these reasons we often find plans, sections and elevations each on separate
sheets or even spread over a number of sheets.
However, a layout for a fairly small building drawn at 1:100 scale may look
something like the example below.
Construction orthographic drawing combines all the skills demonstrated in the
previous exercises. Drawing shapes and combining them into meaningful technical
illustrations then adding text and dimensions is the basis of all technical drawing. It
should always be remembered that a drawing should be attractively laid out as well as
tecnically accurate and easy to read.
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Converting Three Dimensional Objects into Orthographic Drawings
A good quality orthographic drawing of a three dimensional object is only possible if
the person drawing can visualise the finished drawing before starting.
PLAN
Example of FIRST ANGLE PROJECTION (Views from the bottom are rarely shown)
Hidden lines are shown as broken lines.
These are not usually shown on construction
drawings as there may be so many as would
become confusing.
Elevation from right
taken along this arrow
Elevation from left
taken along this arrow
ELEVATION FROM THE RIGHT
FRONT ELEVATION
ELEVATION FROM THE LEFT
REAR ELEVATION
The free hand exercises which follow will provide practice at this important skill and
the scale drawing exercise will convert these skills to a more practical project.
Complete Assignments 1 and 2
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STUDY GUIDE 2: ORTHOGRAPHIC PROJECTION
Assignment No 1 – Converting 3-D objects into orthographic drawings
Produce free hand orthographic drawings of the shapes above in First Angle Projection.
Refer to the extract from BS 1192 for First Angle Projection.
The drawings should show plan, front and side elevations and should be in proportion to the
shapes shown above.
Hidden lines should be shown in an alternative line type.
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STUDY GUIDE 2: ORTHOGRAPHIC PROJECTION
Assignment No 2 – Converting 3-D objects into orthographic drawings
2.0m
3.0
3.0
.5m
m
2.0m
B adius
2.0
m
R
1
2.0
m
45°
4.0
1.5m
C
m
m
1.0
m
2.0
7.0
m
1.5m
m
1.5
3.5m
2.0
A
PLAN
SKETCH VIEW
OF OBJECT
The isometric drawing above shows a three dimensional object drawn at approximately 1:100 scale.
The features marked A, B and C are as follows :
A
B
C
this is a 1m by 1.5m channel cut through the object to meet the channel C.
this is a 1.5m radius cylinder cut through the object in the position shown.
this is a 2.0m by 1.5m channel cut straight through the rear section of the object.
Hidden lines have not been shown on the isometric drawing to assist with clarity.
Draw an orthographic First Angle Projection of the object showing Plan, Front Elevation and Side Elevations
at a scale of 1:100.
All hidden details must be shown using an appropriate line style.
Annotation on the drawing should clearly indicate the names of the views using an appropriate text size and style.
Dimension the drawing using an appropriate style and size of text.
The orientation of the views should be based on the sketch view of the Plan.
The drawing should be enclosed in a Border which should contain relevant drawing information regarding
Unit Title, Student Name, Date Drawn, Scale of Drawing.
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
STUDY GUIDE 3
Construction drawings
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STUDY GUIDE 3: CONSTRUCTION DRAWINGS
INTRODUCTION
Outcome 2
Prepare site layouts and general arrangement drawings for construction projects.
On completion of this Outcome you should be able to:
 describe the types of drawing used for construction projects
 accurately prepare a scale site layout
 accurately prepare a general arrangement drawing for a small building project.
Most of the drawing work you will undertake for the Outcome will be that required
for the assessment assignments of the unit. Additional drawing work may be based
on drawings required for assessment of the other two units of Higher Construction
and for the external assessment project of the Higher course.
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TYPES OF CONSTRUCTION DRAWING
This section deals with the various types of drawing required for a building project,
from the conceptual design stage to the preparation of production drawings. These
range from small scale drawings showing the location of a site in relation to local
geographic and infrastructure features, to very large scale production drawings
showing small details of the construction.
Drawings produced in construction are used by various parties, for example:
 Structural Engineer
 Services Engineer
 Architect
 Planning
 Building Control
 Quantity Surveyor.
Range of construction drawings
Working from the smallest scale to the largest scale used the range may be
summarised as follows:
1 Site Location Plans
2 Site Layout Plans
3 Sketch Drawings
4 General Arrangement Drawings (plans, sections and elevations)
5 Construction Details.
There are also other pieces of information, some of which require drawings, these are:
1 Schedules – for windows, doors, etc.
2 Specifications – materials and construction.
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The scales used for the five main types of construction drawing have been given in
Study Guide 1 but are repeated again here.
Use
Scale
Ratio
Maps
1:1000000
1:500000
1:200000
1:100000
1:50000
l mm to l000m
l mm to 500m
l mm to 200m
l mm to 100m
l mm to 50m
Town surveys
1:50000
1:20000
1 mm to 50m
l mm to 20m
1:10000
l mm to l0m
1:5000
1:2500
l mm to 5m
1 mm to 2.5 m
1 :2500
1:2000
1:1250
Location Plans
1:1000
Site Layout Plans 1:500
1 mm to 2.5 m
l mm to 2m
l mm to l25m
l mm to lm
l mm to 0.5m
Site and key plans
1:1250
1:1000
1:500
1 mm to 1.25m
l mm to lm
l mm to 0.5m
Sketch schemes, etc.
1:200
1:100
1 mm to 0.2 m
l mm to 0.lm
Location drawings
(General Arrangement)
1:200
1:100
1:50
1 mm to 0.2 m
l mm to 0.lm
l mm to 0.05m
Component and
assembly detail
drawings
1:20
1:10
1:5
1:1
1 mm to 0.02 m
1 mm to 0.01m
1 mm to 0.005m
Full size
Other Drawings
Plans and sections (longitudinal and cross) for roads
Fabrication drawings for steelwork
Drainage drawings
Record drawings showing the building ‘As Built’
Survey
Location Plans
The following pages show examples of the main types of construction drawings.
NOTE: The drawings do not relate to the same construction project
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es
fri
m
u
oD
T
Proposed House Site
Town Head
Roundabout
To
D al
bea
ttie
To Auchen
To
n
To
w
tre
Ce
n
Location Plan
This plan shows where the site is in relation to main roads.
It gives directions to officials who may need to visit the site.
The usual scale for this type of drawing is 1:2500 or 1:5000
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FREEHAND SKETCH PLAN AND FRONT ELEVATION
This type of sketch might be done by the Architect (or by the Client) as a way of
working out the positions and approximate sizes of rooms, etc.
It is easy to trace over and finalise the details though some adjustments are usually
necessary when sizes are worked out and the sketches are drawn to scale.
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Room Dimensions
Lounge
Dining Room
Kitchen
Family Room
Utility Room
W.C.
Bed Room 1
Bed Room 2
Bed Room 3
Bed Room 4
Bathroom
4.50m
3.45m
2.95m
4.50
1.80
0.90m
4.10m
4.10m
2.25m
3.00m
1.45m
by
by
by
by
by
by
by
by
by
by
by
4.05
3.60m
3.20m
3.60m
3.20m
2.60m
4.90m
2.75m
2.75m
3.35m
2.75m
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Typical House Ground Floor Plan
The scale for this standard of detail would be 1:50
This is not re-produced to scale but will be approx. 1:70
TYPICAL SCALED SKETCH PLAN
This type of drawing would be part of a set of designs shown to the Clients for them
to make up their minds on which scheme to accept.
The scale used for these is usually 1:100 as the amount of detail required is not critical
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Typical Elevation Sheet for a two storey house
The usual scale for these is 1:100 but if more detail is required a scale of 1:50 can be
used with perhaps only two elevations on each sheet.
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Typical Cross-section Through a Two-Storey House
These sections are usually drawn at a scale of 1:50 and show heights and vertical
angles which are not possible on plan views.
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Typical Construction Detail
Expanded
Polystyrene
Insulation
Reinforced
Concrete
Lintel
Casement
Window
Concrete
Sill
Concrete Floor
with Polythene
Damp Proof Membrane
Concrete
Strip
Foundation
SECTION THROUGH WALL
The detail shows the cross-section through an external wall from foundation to above
window head.
The scale for his drawing would normally be 1:5 but if more detail was required this
may go to 1:2 (Half full size) or even 1:1 (Full size).
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Construction: Manual and Computer-Aided Construction Drawing (Higher). Study Guide 3
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CONSTRUCTION
MANUAL AND COMPUTER-AIDED
CONSTRUCTION DRAWING
HIGHER
STUDY GUIDE 4
Computer-Aided construction drawing
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STUDY GUIDE 4: COMPUTER-AIDED CONSTRUCTION DRAWING
INTRODUCTION
Outcome 3
Use a commercial CAD system to generate construction drawings.
On completion of this Outcome you should be able to:
 use a range of CAD facilities and functions to generate simple drawings of objects
 create CAD drawings for small building projects.
The Study Guide contains a number of exercises, which you should work through
carefully, following the step by step instructions. Your teacher/lecturer will likely
issue you with additional assignments to enable you to gain experience at the
workstation.
As with Outcome 2, most of the work you undertake for this Outcome will be that
required for the assessment assignments of the unit. Additional CAD work may be
based on drawings required for assessment of the other two units of Higher
Construction and for the external assessment project of the Higher course.
The principles considered in the previous Study Guides apply equally to CAD
drawing as to manual drawing. Drawings should be clear, informative and technically
accurate. To achieve these aims requires the same attention to detail as manual
drawing but the special nature of CAD means that other skills have to be learned to
get full advantage.
CAD systems are extremely complicated because what they do is extremely powerful
and sophisticated. There are many ways to carry out the same action and different
situations often require alternative methods. Part of the skill in using CAD is
experimenting with the alternatives and finding new ways to work.
The most successful CAD drawing will be planned before starting so that full use can
be made of the electronic Copying, Mirroring, Rotating etc available in CAD.
Different CAD systems will have different ways to access the commands we are
about to use. You should be aware of any differences between these notes and the
CAD system being used.
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CAD can be used like an electronic drawing board, creating the drawing from lines,
arcs and circles as in manual drawing. The first exercises in this Guide will look at
these basic drawing techniques and then move to the editing and manipulating
techniques which make CAD such a powerful drawing tool. We will conclude this
basic introduction to CAD by looking at lettering and dimensioning.
Remember that we are using basic two dimensional CAD in this unit and that
knowledge of this will be very beneficial when moving on to dedicated three
dimensional Architectural CAD packages.
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REASONS FOR THE USE OF CAD SYSTEMS
Firms who use CAD systems claim many advantages over manual drawing. The
following are only some of the points in favour of CAD:
 increased productivity
 gaining a competitive edge
 easy alteration of drawings
 use of standard and customised libraries increases speed
 alternative versions of drawings can be created easily
 modifications are feasible as the drawing is easy to alter
 teams of designers can work on network versions and see what others are doing
 data can be exchanged between consultants in a standard format
 offices can produce a standard layout of drawing
 quality of draughtsmanship is maintained.
CAD is more than simple electronic draughting. The ability of CAD packages to
provide other functions will make it the only feasible way to produce drawings in he
future. Some of these functions are listed below.






Use of library parts from manufacturers
Automatic Bills of Quantities
Links to Contractors estimating systems
3-D facilities
Rendering to give photo-realistic images
Use of the Internet to pass electronic information including drawings.
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CAD HARDWARE AND SOFTWARE REQUIREMENTS
CAD is one of the most demanding applications for computers. The manipulation of
the data for the many thousands of lines generated in a fairly simple drawing is a
massive task especially as the demand is for instant results. Even slight pauses
between the all important zooms and pans used in CAD are undesirable and can lead
to frustration. When the extra demands of 3-D and rendering are added then the
systems must be of the highest specification affordable.
CAD exists on many platforms but as the PC platform is probably the most common
then it is this one which will be detailed. Similar specifications will be available on
other platforms such as Mac.
Processors, disks and components
As processing speed is increasing weekly it is very difficult to be specific. The fastest
processor along with associated configuration of disks etc should be the requirement.
Currently this would probably include:
 Intel Pentium 3-500
 10 GB Hard disk
 128 MB RAM
 Floppy disk
 CD ROM.
Display unit
 19” colour monitor
 16 MB graphics card.
Pointing device
 Mouse or
 Digitiser
 Pen.
Output devices
 Printer – this gives quick print-outs to check parts of the drawing – should be at
least ink-jet quality
 Plotter – this produces the finished drawing and can be colour with large A0 paper
size – electrostatic plotters give extremely fast output
 Modem – gives access to the Internet.
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Software
There are many CAD software packages available. Each package has its own
advantages and disadvantages, all of which must be evaluated by the purchaser.
Some packages offer customised solutions for particular applications such as:
 Electronic circuit design
 Building services design
 Architectural design
 3-D solid modelling – these can be used to design any 3-D object including
buildings
 Landscape design
 Interior design.
The range of CAD software for 2-D applications is enormous and the price range is
vast. Some of the most expensive packages have ‘cut-down’ versions at a fraction of
the whole package cost. These retain most of the functions of the full package and are
totally compatible. They constitute very good value for money and their introduction
should see an even greater use of CAD in the future.
It is important to keep drawings compatible from system to system as the information
passes through many hands in a design situation. There are some attempts at
compatibility but industry seems to have ‘played it safe’ by opting in large numbers
for AutoCAD which is the world leader in desk top CAD. However, here are many
other good packages which will perform well and give compatibility with AutoCAD.
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CAD SYSTEMS – SCREEN LAYOUT
Most systems work with a series of ICONS which are small squares containing a
symbol. The symbol represents the function which is accessed when the icon is
clicked on. Sometimes the icon will release another group of related icons when the
mouse button is held down on them.
The difficulty in learning CAD is in remembering which icon refers to which
function. Some systems have ‘hot tips’ which pop up when the mouse pointer is held
over an icon for a short time without clicking. This helps when learning the system.
Systems often have a series of PULL DOWN MENUS arranged along the top of the
screen. Clicking on these accesses the menus.
In AutoCAD the icons are arranged in TOOL BARS. Each bar is for a group of related
commands e.g. Draw, Edit etc. The pull down menu system is arranged under
headings which relate to the commands under – some commands have further menus
which drop out when the command is clicked on.
Tool Bar for Draw commands
(same information as in the Pull
Down Menu)
Pull Down Menu for Draw commands with
Circle and all the various ways to define the
circle.
The drawing area of the screen forms the largest area on all systems and it is in that
area that the drawing is made up. AutoCAD also has a Command Line area which
allows commands to be typed and accessed without the need to use icons or pull down
menus.
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All systems will also have other areas which give information on:
 Current position of the pointer
 Drawing mode e.g. Snap, Ortho, Grid, etc. – all of which will be explained later.
Movement around the screen is usually by means of a mouse whose pointer is placed
in the required area. The Left button is used for selecting and often the Right button
acts like the Return key on the keyboard. Total familiarity with the mouse is essential
to gain proficiency in CAD.
Other pointing devices are available such as Digitisers with pen type pointers but
these are expensive and are not necessary for effective drawing in CAD.
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SECTION 1: EXERCISES IN USE OF THE MOUSE
In these exercises you will be drawing shapes using the simple drawing commands
such as Lines and Circles and placing these on a drawing which has a Grid laid out
which will allow easy drawing. The Grid system can be useful in some situations but
most drawing requires lengths to be entered in ways which do not suit simple
rectangular grids. The most common entry systems for distance etc will be dealt with
later.
We will first set up the Drawing Environment to suit the exercise we are about to do.
The drawing environment would be set up for each drawing depending on the size and
other factors of the objects to be drawn.
Remember that drawings in CAD are done FULL SIZE, scale only becomes
important when we are considering the printing or plotting of the drawing. We
will use millimetres as the unit of measurement.
Set up the drawing environment as follows:
SNAP
ON
GRID
ON
SNAP to GRID
Drawing Limits
10 Units
10 Units
Bottom Left corner
0,0
Top Right corner
700,400
Set the ZOOM ratio to ALL to reveal the whole drawing limits.
The drawing screen should look something like below.
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The Grid spacing is shown by the dots and if you move the mouse it should jump only
to the dots on the grid.
If we now want to draw with 20mm increments the Snap and Grid will allow us to do
so.
The exercises which follow are mainly to use the mouse and do not represent actual
objects.
Produce the following shapes calling up the LINE and CIRCLE commands as
necessary.
Save this drawing as Ex1 on your disk as we shall use it later.
You should now be quite familiar with using the mouse and also with drawing lines
and circles, but before we move on we might as well look at some EDITING
functions in CAD.
It is these functions which make CAD such a valuable drawing tool and it is the
ability to adapt a drawing to using these makes for efficient CAD drawing.
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Load the Ex1 drawing back in to the CAD system if you are starting again.
Change the drawing environment to the following settings
SNAP
GRID
LIMITS
OFF
OFF
Lower Left corner
0,0
ZOOM
ALL
to see the whole drawing area.
Upper Right
corner
1400,800
The screen should look something like below.
The Grid has gone and the Snap is off so that you should be able to move the mouse
smoothly around the screen.
The drawing looks smaller because we are seeing a larger drawing area. However, the
objects drawn are still the size we drew them.
If we want to see the objects larger on the screen then we must ZOOM in to the one
we want.
This is done by selecting ZOOM and then placing a WINDOW round the area we
want to zoom in to.
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A window is made by clicking a point below and to the Left of the object then moving
to a point above and to the Right of the object.
The results should be as shown.
Zooming is a very important part of CAD drawing as it is often necessary to work on
a detailed part of a large drawing.
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SECTION 2: EDITING OR MODIFYING DRAWINGS
The drawing we now have can be Edited or Modified using the CAD electronic
methods.
For instance the corners can be rounded or FILLETED using the FILLET command.
This requires a fillet radius to be given to the CAD system then the lines to be filleted
can be selected.
If we set a Fillet Radius of 5 to the above drawing then we can easily alter the shape
showing, and produce the new shape.
The screen should look something like below with the shape now having the filleted
corners.
You might want to fillet the top shapes using different radii of fillet to see the effects.
After some experimenting with filleting zoom in to the two shapes in the middle at the
bottom.
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The screen should now look something like below.
We are now going to add lines to join up points all ready on the drawing.
It is often quite difficult to make neat intersections on the drawing board but this is
easy on the CAD system using OBJECT SNAPS. These allow the computer to find
points such as ENDs of lines and arcs, INTersections of lines or arcs, CENtres of
circles or arcs, TANgent points, MIDdle points of lines and many others.
Add the lines as shown below using the appropriate Object Snaps. Remember that
attempting to judge these intersections by eye is virtually impossible even if Zoom is
used and totally unnecessary as it is very easy to do with a bit of practice.
Save this version of the drawing as EX2. This retains EX1 in its original form and
now gives us version 2 to work with. If something drastic has gone wrong with
version 2 then we can get back to EX1 as if nothing had been done to it.
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We will now look at some other Editing or Modifying features.
It is important that we can remove parts of the drawing no longer required, this
command for this is ERASE in AutoCAD.
Open the drawing previously saved as EX2.
Zoom ALL to see the whole drawing.
Call up the ERASE command then Window round all the shapes except the shape
shown below.
Zoom in on this shape so that it fills the screen as above.
We will now look at different ways to partially erase objects from the drawing to
leave the finished shape. This is the type of procedure which would be like rubbing
out construction lines on the drawing board. There are a number of ways to do this in
AutoCAD but we will use one called TRIM.
The TRIM command allows us to trim objects to ‘cutting’ edges so that what is left
makes correct junctions with these edges. This will apply to lines and arcs or circles.
Call up the TRIM command. It asks to select the cutting edges.
Select both of the lines radiating from the centre of the circles on the Left – these will
be the edges to which intersecting objects will be trimmed.
After selecting these edges the system asks to select objects to be trimmed.
Select any object which crosses both the cutting edges and the part of the object
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selected will be trimmed between the cutting edges. Select the circles by clicking on
the circumferences to the right of the cutting edges. The end result should look like
shown below.
Use the TRIM command some more on the shape to produce the final version as
shown below.
Save this shape as EX3.
We will now use a further Modifying command which allows this shape to be
repeated without any further drawing.
Zoom ALL to see the whole drawing screen again.
Call up the COPY command.
Select the whole of the object. When selection is finished press RETURN and you
will be asked for a ‘base point’. The base point is the point of reference for the copy
and it is important to choose a point which will be useful when asked where to copy
to.
Select the INTersection which makes the point of the arrow on the shape. (Remember
to use the OSNAP method to select this point.
Type in the following (this will be explained in a moment) for point of displacement.
200<90
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A copy of the shape should appear above the original shape.
What has happened is that we have asked the system to copy selected objects and then
told the system where to place the copy.
The Base Point and Point of Displacement parts of the Copy command are important
as they occur in other commands in the CAD system such as Move so it is best to get
used to them early on.
Typing in he values 200<90 in the copy command above is using the most common
method of specifying distances in a CAD system. That is using POLAR COORDINATES.
We shall look at this in the next section.
Try a few other Modify or Edit commands using the shapes on the screen.
Especially try MOVE and ROTATE.
Add some lines and circles to the shapes to get familiar with these basic drawing
commands.
Remember to use the OSNAP method when selecting points.
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SECTION 3: ACCURATE DRAWING WITH SIZES AND ANGLES
Up to now the shapes we have drawn have not been to any specific size.
We have been sketching rather than drawing. However, most technical drawing has to
be accurate and to given sizes.
The CAD system can produce a degree of accuracy which far exceeds that of the
drawing board, to such an extent that sometimes this is seen as a problem as nearly all
the information about what we are drawing should be collected before drawing starts.
We can still use construction lines and erase them at a later stage but the Copy and
Move functions along with other Modifying functions such as Trim and Extend and
Mirror give us more tools to make drawing easier.
To draw a line accurately for example we must know :
1
the start point of the line
2
the finish point of the line
The start point may be anywhere on the drawing so we might simply select with the
mouse or we may want to start on the INTersection of other lines (select with OSNAP
INTersection).
The finish point of the line will have either :
Known distances horizontally (X) and vertically (Y)
or
A known distance and a known angle
CO-ORDINATES
POLAR CO-ORDINATES
In both cases it is most common to know distances and angles RELATIVE to the last
point selected.
The selection of finish point (or NEXT point) will usually be done using RELATIVE
CO-ORDINATES or RELATIVE POLAR CO-ORDINATES.
Methods of entering distances and angles
Relative Co-ordinates
Type in the @ character (to show relative) then follow with (or select on some
systems) first the X or horizontal value, separate with a comma then the Y or vertical
value.
Example
Start a new drawing.
Select the LINE command
Start the line anywhere on the screen by clicking the mouse.
For next point type in:
@100,100
A line should be drawn from the start point to a point which is 100 horizontally and
100 vertically from the start point.
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Continue the lines with relative co-ordinates typing in values for X and Y when asked
(remember the @ before each set of co-ordinates and the comma between the X and
Y).
Try negative values to go to the left and down.
Relative Polar Co-ordinates
Type in the @ character (to show relative) then follow with (or select on some
systems) first the distance then the < character (to show angle) then the value of the
angle.
Example
Select the LINE command
Start the line anywhere on the screen by clicking the mouse.
For next point type in :
@120<45
A line should be drawn from the start point to a point which is 120 long and at 45
degrees to the horizontal.
The angle to type in can be as accurate as you need, say 32.4564 degrees and can go
round the whole 360 degrees of the circle.
This means that the following angles give the following lines
0
90
180
270
horizontal and to the right
vertically up
horizontal and to the left
vertically down
All angles in between give lines in the four quadrants of the circle.
Experiment with line drawn using polar co-ordinates.
Remember the @ before each set of co-ordinates and the < before the angle.
These two methods of inputting sizes and angles in to the drawing and the use of
OSNAP to fix on to ENDs, INTersections, MIDdle points, CENtres etc make the
CAD system a very accurate.
Electronic copying, moving rotating, mirroring, trimming, extending and offsetting
etc all limit the amount of actual drawing needed so that once an accurate shape is
generated a complete complex drawing can produced in minimum time.
Use the Co-ordinate system to produce the drawing shown with the sizes given.
Set up a drawing with the following settings:
Limits
0,0
30000,18000
Snap
off
Grid
off
Ortho
off
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We will use the usual convention in Architectural drawing of using millimetres as the
drawing unit so we can set Units to decimal with no places after the point and decimal
degrees with 3 places after the point.
Zoom all as before to see the whole drawing area before starting to draw.
Exercise 4
Line
(select a point about half way up the screen and near the left edge.
(Next point)
@15000<0
@3000<90
@10000<180
PER (for perpendicular osnap) – click on bottom line
Return to end the line command.
The shape should look as below
Line
Select the MID point of the top line as the start
(Next point)
@0,2000
@INT (for intersection) – click on top left corner of shape
Return to end the line command
Line
Type END and select the top of the vertical line just drawn
Type INT and select the top right corner of the shape
The shape should now look as below
Trim
Select the left vertical line as the trimming plane – and return
Select the bottom line outside the shape as the part to be trimmed
If you select the wrong place or make any mistakes type or select UNDO for the last
action to be undone. This can be repeated many times.
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Erase the vertical line at the top.
The shape should now look like as below
Offset
(offset distance)
400
Select the bottom line as object to offset
Select a point above the line as side to offset
Return to end this offset command
Offset
(offset distance)
200
Select the top horizontal line
Select a point below the line as side to offset
Return to end the offset command
The Shape should now look as below:
Line
Select the MID point on the first offsetted line
@2000<90
Return
Offset
(offset distance)
450
Select the last line drawn
Select a point to the right of the line as side to offset
Select the last line drawn
Select a point to the left of the line as side to offset
Return
Erase the middle vertical line
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Draw a line to join the tops of the two vertical lines.
Line
Select the top left intersection of the door as the start
Select a perpendicular to the left wall line
Return
Offset
(offset distance)
500
Select the left vertical side of the door
Select to the left of this as the side to offset
Select the left wall line
Select to the right of this as the side to offset
Select the second bottom horizontal line
Select a point above this
Return
The shape should now look as below
Trim the lines to end up with the shape as below
Line Select the intersection with the right hand wall line and the second bottom
horizontal line
@1000<90
@800<180
@1000<90
@1200<180
@1000<270
@1200<0
Return
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Erase he lines to end up with the shape as below
Line
Select the mid point of the vertical left side of the new window
Select a perpendicular to he right hand side of the door
Return
Circle Select the mid point of the last line drawn as the centre of the circle
Type 500 as the radius
Return
Erase so that the shape now looks like below
Mirror Select the whole shape
Return
(First point on mirror line) Select the bottom right hand side of the shape
(Second point on mirror line) Select the top right hand side of the shape
Type N not to erase
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We should now have a pair of houses joined in the middle as below
Save this drawing as EX4
We have now used a number of drawing techniques to construct a pair of houses.
These techniques can be used to construct any type of drawing and so it is best to
practice as much as possible and use as many of these and other commands available
to find the best ways to produce a final drawing.
Remember to plan your drawing so that you use as many of the electronic techniques
such as offset, mirror, copy, move etc as possible and do as little drawing as possible.
You should now do as many drawing exercises as time permits. Try the exercises in
the Manual Drawing Study Guides for practice.
Save the drawings with unique exercise numbers.
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SECTION 4: ADDING TEXT OR ANNOTATION TO THE DRAWING
As with manual drawing the text on the drawing gives important information to the
reader.
The text must therefore be clear and positioned so that it does not obscure any drawn
detail.
Most CAD systems have pre-loaded text styles and these can be easily accessed to
position the best size and style appropriate to the information being given.
Some information, such as titles, must be larger than others and can be in a more
elaborate style but for most text, readability is most important.
Choose a style and size which will print out in a readable format.
Text on CAD will be easier to do than manually drawn text but care must still be
taken over position and the overall appearance of the drawing.
AutoCAD allows he user to customise text by choosing from the many Fonts
available and making these into Text Styles.
This is done by Formatting a New Text Style using the dialog box shown.
The style of text can be called up and the height given for any annotation required.
It is also possible to insert pre-typed text from Word Processing files.
Use the Text functions on your system to add annotation to the Drawing exercises
which you have done.
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SECTION 5: ADDING DIMENSIONS TO THE DRAWING
As with text, dimensioning in CAD is relatively easy. The drawing was constructed
using accurate sizes and it is these sizes which the CAD system will use in
dimensioning.
It is usually possible to over-ride the suggested sizes and this is allowable provided
the difference is not too great.
Units for dimensioning are usually set up before dimensioning starts and it is as well
to remember that all sizes entered are probably in Millimetres and will come out as,
say, 2314 for millimetres not 2.314 for metres. It is usually possible to have
alternative units which could be metres if required but this takes up a lot of space on
the drawing and may not be practicable.
Dimensions can be:
Linear
Horizontal, Vertical or Aligned
Angular
between two lines
Radius or
Diameter
for Circles or Arcs
In most cases dimensioning is automatic with the user simply selecting the type of
dimension and then pointing to the object to be dimensioned. The position of the text
and the dimension line can then be selected.
AutoCAD allows many Dimension Styles to be created and applied by using the
dialog boxes shown.
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Different boxes allow customisation of extension lines, offsets, text position and
many other things.
Use the Dimensioning functions on your system to add dimensions to the Drawing
exercises which you have done.
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SECTION 6: ADDING HATCHING TO THE DRAWING
Hatching can be used to highlight certain areas of the drawing and may also be used
to show different materials in sections etc.
Most CAD systems have their various ways to hatch shapes and it will be necessary to
experiment with your system to see the best hatching method for the drawing you are
doing.
Scale is important in hatching as too small a scale will result in a totally filled area
whereas too large a scale will only show a small part of the hatching.
Text within hatching can be done in a box then the box removed after hatching.
Some Hatch Patterns Available in AutoCAD
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TEXT
Insert the text in the area to be hatched.
TEXT
Hatch the area.
TEXT
Draw a box round the text.
TEXT
Erase the box.
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SECTION 7: EXAMPLE CAD DRAWINGS
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FRONT ELEVATION
C. Rigg Dumfries
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LEFT ELEVATION
C. Rigg Dumfries
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UPPER FLOOR PLAN
ELEVATION
This technique saves considerable time over
manual drawing.
This drawing shows the use of block insertions.
The bedrooms in this hotel were drawn once then
made into blocks and inserted as required.
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