IES Salvador Rueda – Dpto. Tecnología
Unit 2: Graphic expression and communication
Technical Drawing
TECHNOLOGY – IES Salvador Rueda
Index
•Introduction•Drawing materials•Drawing tools•Sketches, outlines and plans•Scale•Views of an object (Diedric system)
TECHNOLOGY – IES Salvador Rueda
INTRODUCTION: previous questions
� What differences can you find between technical drawing and artistic drawing?
� What measurement tools do you know?
� How would you draw a chair if you wanted to know its real measurements?
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INTRODUCTION: Definitions
• Drawing is a form of communication which allows us toexpress ideas easily.
• Using a drawing we can represent, for example:Ø The plan of a building.Ø The instructions to make a toy.
• There are two types of drawings:q Artistic drawing: We use it to express feelings.q Technical drawing: We use it to represent an object in
an exact way.
“An image is more useful than one thousand words.”
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DRAWING MATERIALS
Pencils
Erasers/rubbers
Technicaldrawing paper
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DRAWING MATERIALS: Pencils2 parts
Covering made of wood
Hardness:ü Medium pencil: HB (the most common)
ü Soft pencil: B-2B-3B-4B-5B-6B
ü Hard pencil: H-2H-3H-4H-5H-6H
•The hardest lead is the 6H.
•The softest lead is the 6B.
Lead made of graphite
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DRAWING MATERIALS: Pencils II• Using soft pencils we can draw thick lines. This is thereason why they are useful in artistic drawing.
• Using hard pencils we can draw thin lines. This is thereason why they are useful in technical drawing.
• The HB pencils can be used in artistic and technicaldrawings. We will usually use this one.
Other: pen (ink), felt-tip pen, colour pencils, stylographs.
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DRAWING MATERIALS: Eraser
•It is made of rubber!
•We use it to erase the lineswe are not interested in.
“The secret to technical drawingis avoiding using the eraser!”
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DRAWING MATERIALS: PaperThree important features:� SIZE� THICKNESS: mass of paper
divided by its area (g/m2)� APPEARANCE
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DRAWING MATERIALS: Paper II
Size or format: Standard size
The A4 size is double size of the A5 size
The A3 size is double size of the A4 sizeThe A2 size is double size of the A3 size
The A1 size is double size of the A2 sizeThe A0 size is double size of the A1 size
Very important: A sheet of paperand an A4 size paper are not thesame! (a sheet of paper is bigger)
We will usually use the A4 size.
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DRAWING MATERIALS: Paper III
APPEARANCE
Bright Texture Colour
Matt Satin Smooth Rough Coloured White
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DRAWING TOOLS: Measuring toolsRuler
• It is a precision tool that makes it possible to measureand to transfer a distance.
Protractor• We use a protractor to measure and draw angles
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DRAWING TOOLS: Tools for drawinglines
TRIANGULAR SET SQUARE • A set square is a tool to draw perpendicular (vertical)
and parallel lines and to obtain angles. • There are 2 types of trianglular set squares
Compass• Used to draw circles and arcs.
A right-angledisoscelestriangle(escuadra)
A right-angledscalenetriangle(cartabón)
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DRAWING TOOLS
Compass
A 45 degreesquare
A 60/30 degree square
Graduated ruler
Protractor Template / Stencil
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DRAWING TOOLS
How to draw vertical and parallel lines with the set square.
Vertical Parallel
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DRAWING TOOLS
Drawing angles: we can get 15º, 30º, 45º, 60º, 75º, 90º, 120º, 135º…angles combining the 30º, 45º , 60º
and the 90º angles from the set squares
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OUTLINE & SKETCH(Boceto) (Croquis)
• It is the first drawing that wemake from an object.
• It is hand-drawn
• It is quickly drawn.
• It doesn’t include many details or exact measurements.
• It is the definitive graphic representation of the idea.
• It isn`t hand-drawn. We have to use drawing tools
• It includes many details and exact measurements.
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PLAN (Plano)• A plan is similar to a sketch but…▫ It is drawn with rulers or computers.▫ Its precision is bigger than the sketch.
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PLAN: Presentation
Cartouche/information grid: it is a space in the plan where we can readthe most important information about it:
▫ Project name▫ Plan tittle▫ Person in charge / Made by▫ Date▫ Scale: It is the proportion between the
drawn object size and the real object.
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SCALE
Scales• Enlargement scales (2:1), (100:1)
• Reduction scales (1:100), (1:10000)
• Full size or natural scales (1:1), (100:100)
• We use enlargement scales when we want to draw objectswhich are smaller than our paper (we want to see thembigger).
• We use reduction scales when we want to draw objectswhich are bigger than our paper.
• We use full size scales when the size of the object that wewant to draw is the same to that of our paper.
-Enlargement scale: When the numerator is biggerthan the denominator.- Reduction scale: When the numerator is smaller thanthe denominator.
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Scales: Exercise 1
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Scales: Exercise 2
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Exercise 3
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Views of an object: diedric system
• The diedric system represents the objects using a perpendicular projection on a plane.
The projection or VIEW consists of drawing just what we see when we are perpendicular to the
object and to the plane.
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Views of an objectThe main views of an object are theorthogonalprojection of itselfon the 6 planes of a cube, so sixviews are possibledepending on thedirection we watchan object from.
Front view
Right side view
Plan/ Top view
Rear view
Left side view
Bottomview
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Views of an object: The Glass Cube
• Imagine you have a glass box (cube) and an object inside it. It isnecessary to unfold the planes as ifthey were in the same plane torepresent the figure in 2D.
� By unfolding the box, six views of the object are possible:
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Views of an object: main views�Normally the object is drawn as three separate,
related views because in this way, the object is fully described. These typical views: › Front View: is a drawing of the object as if you
were looking directly at the front of the object.› Side View (Left or Right): is a drawing of the
object, when it has been rotated so that one of its sides is now directly in view.› Plan View: is a ‘birds eye’ view, from above.
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Example of Views I
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Examples of Views II
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Important note!!!
WRONG RIGHT
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EXERCISES�Draw the missing views and write the name of
the different views.
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Glossary
• Paper size• Sixty and forty five degree set squared• Graduated rule• Sketch, freehand drawing• Measures• Scale• Real and drawn size, reduction, enlargement scales • To be reduced 100 times• Length, height, width• Long, high, weight• Front, plan, side view• Straight lines: Parallel, perpendicular. Arcs, circles and curves.• Verbs: To write / To draw / To erase / To mark / To measure/ To match
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