rd
3
Angle
Orthographic
Drawings
aka ‘ortho’
What we going to be doing over
the next few days….
By the end of this unit, you should be able
to recognise, understand and draw using
the technique of ‘orthographic drawing’
Orthographic drawings can also be known
as working drawings or production drawings.
What are Orthographic
Drawings?
• Orthographic drawings are a way of drawing a
three dimensional object, in 2D.
• They are accurate drawings which are followed
exactly when making a final design.
• They contain specific information that is needed
to produce this final design.
• These details need to include dimensions,
materials and construction instructions.
• Without orthographic drawings we would be
unable to make and construct things to what you
had planned (like your playhouse).
Orthographic Drawings
In the Classroom
•In Design and Visual Communication (DVC)
/Graphics, orthographic drawings are created on
paper, and on the computer by using Illustrator,
ArchiCAD, or Google SketchUp.
In Everyday life
•Orthographic drawings can be found in any type
of manufacturing industry, including architects,
builders and other individual crafts people. These
are created using many different computer
programmes such as CAD, ArchiCAD, Solidworks
etc, and manually with paper also.
Equipment needed
Sharp pencil, a set square, a T square, and
a graphics board; and in future, a compass.
Different types?
• There are two different types of orthographic
drawings. The first is called ‘first angle
projection’ which is used in the United Kingdom
and the second is called ‘third angle projection’,
which is used in the USA, Australia, and NZ.
• We will be reviewing third angle projection
Different Views?
• When you draw an object or a product you draw it in three
different views: Front View, Side View and Plan View.
Positioning of Views
• Now that you know of the three different views
that an object is drawn in, it is important that you
now learn how to position these.
• The next slide shows the same object that was
drawn on the previous page, only now it is in its
proper positioning according to the rules of third
angle projection.
Positioning of Views
Ensure
EVERYTHING
is in line
SEE ANIMATION EXAMPLE
http://www.technologystudent.com/designpr
o/orthogrp1.html
Or
http://metal.brightcookie.com/2_draw/draw_t
3/htm/draw3_2_5.htm
PLAN VIEW
FRONT ELEVATION
SIDE ELEVATION
Extend all construction lines,
then add a 45˚ line to show
where the end view should go.
When the drawings get more complicated
you will find this essential.
PLAN VIEW
FRONT ELEVATION
SIDE ELEVATION
What it looks like when drawn correctly:
PLANNING
YOUR WORKING DRAWING
(so that it will show what you want it to show, and
so that it will fit on your A3 paper)
• When deciding which view will be your ‘front
elevation’, select the longest length OR if lengths
are similar, the view with most detail on it.
• When deciding whether to show 3 or 4 views
(two side views), only do this if both sides have a
lot of different details eg. Many
windows/angles/curves, that are too many to
show using hidden detail.
Contd…
• Sketch it on scrap paper how it will look first.
• Once you have selected which view to show,
then plan out where to position your drawing
on an A3 sheet of paper by measuring it out
roughly to check that your views will fit before
starting. This may require scaling.
Sketch it first… eg.
In groups of 3
• Discuss: your given object and
• Select: which will be your PLAN, FRONT
ELEVATION, and SIDE / END ELEVATION
• Sketch: carefully on your A3 sheet how it would be
laid out.
• Include: Reference lines and 45degree line.
• Ensure: each elevation is lined up, and that you
have used light construction lines to do this.
• Explain: why have you chosen each view to go
where.
BEGINNING
YOUR WORKING DRAWING
• Begin the drawing that has the most detail first,
either your PLAN, or your FRONT ELEVATION
(ensure it is positioned where you planned it to be)
• Once you have drawn this and it has it’s main
outline correct, add your first reference line.
Reference lines must be evenly spaced between
each object, 20mm from each object is usually
best.
• Then, begin the one you didn’t do, leaving your
end elevation for last
Let me see that ‘correct’ one again…
contd…
• Once both PLAN, and FRONT ELEVATION are
complete, then draw your last reference line
20mm away from your front elevation. Add your
45degree angle from the corner of your two
reference lines.
• Finally, project across from your FRONT
ELEVATION, and across and down (at the 45’
line) from your PLAN to create your END/SIDE
ELEVATION. This will automatically be
positioned correctly due to projection.
again…
Different types of lines?
1.
Construction lines - these lines are feint lines that are used
when planning out the drawing.
2.
Outlines - these lines are a heavier than the construction
lines. They are the lines that are used to actually draw.
3.
Reference lines – (long, short short) used for orthographic
projection to separate views/ planes eg. HP, VP, VP1, VP2
4.
Centre lines – these lines are alternate lines and dots which
identify the centre lines of a symmetrical object.
5.
Hidden detail lines – these lines are short dashes of equal
length and spacing. The lines are used to show something
that is hidden for example like a hole or an edge.
6.
Dimension lines – these lines show the measurement
between two points. And are drawn finely.
7.
Dimensioning arrows – 3mm long by 1mm thick
wait, again…
TASK
• Practice each “Different types of line” on
your blank A3 paper. Using instruments.
TASK
Sketch the
following
shape, in
orthographic
on your A3
paper. Include
all line work.
When you add measurements
to your drawings you must do
it in a certain way…
Measurements are added to your
drawing, using ‘dimension lines’.
•Write the number only above the line.
•Use small arrow heads (1mm by 3mm).
•Use construction lines to show where
measurements link to in the drawing.
•Write‘MEASUREMENTS IN MM’ in
the title block.
cont’d…
• The size of the dimension that is written on the
drawing must be the actual size that will be built.
• No unit (eg. mm) should be written on the
dimension line. The unit that you are working in
should be written in your title block (e.g. mm,
m…etc).
• You can’t have the same dimension twice.
cont’d…
• Only need to write the dimensions that you need
to draw.
• The centre of circles and holes are indicated by
a cross.
• The radius is indicated by a R
• The diametre is indicated by a
TASK
• Using instruments and a new A3 sheet, you
are now required to recreate the following
drawing according to the rules and positions
for third angle projection.
• You must include a title block, scale,
‘measurements in mm’, proper dimensions,
accurate line work, correct layout, drawing
titles, HP, VP, VP1, VP2.
• Set up your title block first.
FINAL TASK
• Using the shape you selected earlier you
are now required to draw your shape
according to the rules and positions for
third angle projection. You will need
instruments and a new A3 sheet
• You must include a title block, scale,
‘measurements in mm’, proper
dimensions, accurate line work, correct
layout, drawing titles, HP, VP, VP1, VP2.
• Set up your title block first.
Scale
• You need to scale objects and products as in
many cases they are far too big (or too small) to
be able to draw their actual size on paper.
• It is important to remember that if you are
scaling down or up then all the measurements
must be altered by the same factor. To do this
we use a ratio - Actual size: Drawing size.
Scale
• Ratio can be converted into fractions, like what
you use in maths.
• For example if your drawing is to be tenth of
what it actually is then you need to divide the
actual dimensions by ten to get your drawing
dimensions.
• i.e.
Scale is 1000:100
Drawing
Actual
= 100
1000
= 1 answer 1:10
10
TASK
•
You are required to work these ratios out
to scale on your A3 sheet.
•
•
•
•
100:25
60:20
1000:200
450:50
The Scale Table
• The scale table is constructed by listing all the
dimensions to be shown, their actual sizes and
then their drawing sizes.
• Remember to look back at your “Scale” notes on
the previous pages if you get stuck!
• In your notes you can see a scale table, this
shows hypothetical information, you are to
complete the task.
TASK
• You are required to fill in the uncompleted table
in your notes according to the scale.
NEXT: It is important to listen very carefully to the
teacher’s demonstration as it will benefit you greatly
for the next task you are required to complete.