unit 2: graphic expression and...

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)


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?


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.”


DRAWING MATERIALS

Pencils

Erasers/rubbers

Technicaldrawing paper


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


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.


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!”


DRAWING MATERIALS: PaperThree important features:� SIZE� THICKNESS: mass of paper

divided by its area (g/m2)� APPEARANCE


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.


DRAWING MATERIALS: Paper III

APPEARANCE

Bright Texture Colour

Matt Satin Smooth Rough Coloured White


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


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)


DRAWING TOOLS

Compass

A 45 degreesquare

A 60/30 degree square

Graduated ruler

Protractor Template / Stencil


DRAWING TOOLS

How to draw vertical and parallel lines with the set square.

Vertical Parallel


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


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.


PLAN (Plano)• A plan is similar to a sketch but…▫ It is drawn with rulers or computers.▫ Its precision is bigger than the sketch.


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.


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.


Scales: Exercise 1


Scales: Exercise 2


Exercise 3


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.


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


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:


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.


Example of Views I


Examples of Views II


Important note!!!

WRONG RIGHT


EXERCISES�Draw the missing views and write the name of

the different views.


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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