Graphic representation of technological projects

Expression of ideas, feelings and emotionsthrough drawing.

It’s used to express ideas… from very simple toreally complex.

Drawing is a universal language.

Written characters are drawings.

Artistic drawing:

- No rules. Freedom.

- Used to express emotions or to create beauty.

- Broad variety of tools.

- It can be messy and caotic.

Technical drawing:

- International rules.

- Used to transmit ideas and create projects.

- Made with tools that achieve accuracy.

- It must be clean and ordered.

Accuracy: Precision.

You must presentcleanly andorderly FOR REAL.A percentage ofyour drawing’smark will alwaysdepend on theircleanliness andpresentation.

Do the following drawings transmit ideas orfeelings?

Do you think they are artistic or technical drawings?

Are they graphic representations of things?

Looking for solutions to a problem.

Organizing ideas.

Designing objects in detail (parts, dimensions,assembly…)

Showing ideas to other people and debatingabout them.

Giving instructions to assemble a product.

Adding aesthetic value to a design.

To assemble: To mount, put together.Aesthetic: Tasteful, beautiful.

LOOK AT the spelling of this word:D-E-S-I-G-N

DIN A4210 x 297 mm21 x 29,7 cm

DIN A3297 x 420 mm29,7 x 42 cm

DIN A2Can you guessits size?

DIN A1Can you guessits size?

DIN A0Can you guessits size?

They are used directly on paper to draw.

PENCILS Hardness.

H = Hard (the higher its number, the harder)

HB= Medium

B = Bland (the higher its number, the softer)

TECHNICAL PENS Thickness.

FELT-TIP PENS Colour.

Using the right pencil for everysituation will be crucial for yourmarks.

They help us to draw accurately.

45º SQUARE 30º (or 30-60º) SQUARE

PROTRACTOR

RULER

COMPASS

LOOK AT the spelling of this word:P-R-O-T-R-A-C-T-O-R

First place the long sideof the 45º square in contact with your

reference line

To draw parallel lines, slide the 45º square

To drawperpendicular lines, turn the 45º square

around withoutmoving the 30º

square

Slide the T-squareand draw on its

long side.

You must control thistechnique FOR REAL. Apercentage of yourdrawing’s mark will alwaysdepend on the accuracy ofyour parallel andperpendicular lines.

Parallel lines: Never meeting orspreading away.Perpendicular lines: Crossing at a straight angle (90º).

Rough lines, rapidly executed

Normally it consist of a multitude of overlappinglines (we use no rubber)

Not finished

Creating Used to think, discuss about possiblesolutions, define measurements, solve detailsabout certain parts, designing the assemblyprocess…

Observing Used to take notes from real objectslike measurements, materials, shape…

Freehand: drawn usingno auxiliary tools.Rough: Unfinished.Overlapping: Lying onesover others.

They can be more or less detaileddepending on the stage of thecreative process.

LOOK AT the rightpreposition:

To depend ON something

Stage: Phase, step.

GRAPHIC Only based on lines,

symbols and numbers.

UNIVERSAL Understandable by any technician inthe World.

PRECISE Drawn with care, cleanliness andaccuracy.

COMPLETE Including every detail necessary tobuild the object (measurements, materials, parts,assembly…)

APPROPRIATE Every drawing requires a differentscale, level of detail, medium… depending on itsfinal user.

LOOK AT the rightpreposition:

To be based ON something

In the context of technical drawing, Standardisationis the set of rules that regulate all the elementsthat form part of graphic representation.

Standardisation allows for a drawing to beunderstood internationally.

Some set of rules:

AENOR in Spain

DIN in Germany

UNE in Europe

ISO international

ANSI, ASA in the USA

Standardisation regulates: Paper formats Line types Annotation Scales Labelling Abbreviations (…)

Labelling is the set of letters, numbers and symbols thatgo with a drawing to complement it.

We will use the following rules: Labelling must be done freehand. The letter’s height must be appropriate for the

drawing. Some standard heights are (mm):2’5 3’5 5 7 10 14 20

Use a 2H very sharp pencil. Lines must be dark and well traced. Your letter must be vertical and technical. Auxiliary soft parallel lines must be used.

To trace: To draw.A set of: A group of.

From now on, alllabelling you needto include in yourdrawings must bemade respectingthese rules.

On a page of your A3 drawing pad, trace 3 pairs of auxiliary lines at a 7 mm distance. Spacing: 3’5 mm.

Write your name and surname in capital letter in the first pairof lines.

Write your name and surname in lower case letters in thesecond pair of lines.

Write your birth date in the third pair of lines.

Spacing: The free spacebetween two written lines.

Use this vertical standardized labelling

style (DIN17).

There are two main line types:

Lines that define the drawing. Types:

a) Continuous thick lines (2B) Edges and cuts.

b)Dashed thin lines (2H) Hidden edges.

c) Dashed thin lines with dots (2H) Axis ofsymmetry.

Auxiliary lines.

Continuous thin

lines (2H).

On the page where youpractice your labelling, draw a sketch of the threeflat views of this object.

Try to keep the proportionsalthough you don’t knowits measurements.

Now, draw them with yourset squares using the righttypes of lines.

Annotation consists of expressing the real measurementsof an object on a plan.

Annotation makes the plan easier to read and interpret. Itallows us to see the measurements of an object at aglance.

Annotations must be clear, cleanand precise:a) Drawn more lightly than the

lines of the drawing.b) Parallel lines must be REALLY

PARALLEL.c) The size of the numbers must

be not too big nor too small.

Plan: Technical drawingthat represents a view of an object or building.

LOOK AT the rightspelling:

A-N-N-OTATION

a) Extension lines Thin, continuous (2H) Theyindicate the portion of the drawing we aremeasuring.

b) Annotation lines Thin, continuous (2H)

Parallel to the edge (at the right distance) andmeasuring the same.

c) Arrow heads Thin (2H) On both annotationline endings, they indicate the dimension labelled.

d) Annotation Thin and correctly labelled (verticalstandard writing) (2H) Number that indicatesthe real measurement of the portion annotated.

Arrow headAnnotation line

Annotation

Extensionline

Different arrow head styles

Pay attention to all these rules and learn bypractising. A drawing needs to abide by theserules to be good.

1- Annotations must never be written on the edge but ontop of the annotation line.

2- Annotation lines must never cross, touch or overlap anedge of the object. Extension lines must be used. Leavea reasonable distance (0,8 cm minimum) betweenedge and annotation line.

3- Extension lines extend 2-3mm from the annotationline. They must touch theedge they are marking.

4- Annotations must beplaced above the line and centered on it. On vertical edges, think about a clockwise turn.

5- The units must never beindicated on the annotation. We just write themeasurement (normally in mm) and express the unitson the plan.

DIMENSIONS IN mm

6- You must indicate all necessary measurements forbuilding the object.

7- You must not repeat any measurementunnecessarily.

8- Annotation lines must never cross nor cross an edge. It’sfine to cross two extension lines or an extension line andan edge.

To avoid crossing, we must plan the position of theannotation lines carefully.

9- We must arrange annotations in an orderly way.

Standard annotation

systems

ANNOTATION OF ARCS AND

CIRCUMFERENCES

We use the SYMBOLS R (radius) y Ф (diameter).

We draw with DASHED LINES WITH DOTS twodiameters (vertical and horizontal) and the center ofthe arc/circumference. The annotation line must beDIAGONAL.

If the annotation doesn’t fit inside, we can extend theannotation line and write it ouside.

ANNOTATION OF

PERSPECTIVE DRAWINGS

Extension and annotationlines must always beparallel to the edges ofthe object.

Go back to the frontview of this objectyou drew in yourpad.

Measure it and writeannotations, following all therules.

FLAT VIEWS

The flat views (o dihedral views) of an object are 2 dimensionimages perceived by an observer placed on a plane parallelto the object’s main sides.

We draw them following the European system.

PERSPECTIVE Plane: A flat or level surface.

Drawing a perspective istrying to show a 3dimensional reality onto a 2dimensional medium.The perspectives that we’lluse are cavalier andisometric perspectives.

Dihedral: having or containingtwo plane faces.

Remember:

NOUN - ADJECTIVEHeight – HighDepth - DeepWidth - Wide

Front, side and top views arethe result of projecting anobject onto an imaginarytrihedron.

That trihedron, with the 3projections, later unfoldsand shows the views incorrelative positions.

Trihedron: Volume formed bythree planes that intersect at three 90º angles.

2nd step: Name the threeaxes x, y, z on theperspective and drawthem in 2D. Draw a line at a 45º angle in the bottom rightsector.

z

y

x

z

y

x

x

1st step: Colour what’s seen from everydifferent view point. A slope is seenfrom two view points.

LOOK AT the singular and the plural:

AXIS (singular)AXES (plural)

You must always label allthree axes and use the 45ºline.

The teacher will teachyou a method that

you must alwaysuse.

3rd step: Draw the frontview in the xy sector. Keep the measurementsof the perspective.

Don’t make your viewlean on (touch) theaxes.

4o step: Draw the side viewin the xz sector at thesame height as thefront. Use auxiliary lines.

5th step: the top view in thexy sector using the 45º line and auxiliary lines. It must be right underthe front view.

z

y

x

IMPORTANT: The three views must becorrelatively placed. We use auxiliary softlines and the 45º angle line to achieve that .

REMEMBER: Hidden edges are represented bydashed lines. Symmetry axes by dashed lineswith dots.

z

y

x

x

Front view

Front view Side view

Top view

Draw the threeviews of theseobjects withyour set squareson a page of your drawingpad. Keep themeasurements: a little cube is 3 cm side.

It’s a 3 dimensional representation of an objectformed by three axes separated by 120º angles.

The true dimensions of the object are respected (weconsider no distortion because of the depth, whichis not realistic).

Distortion: Deformation.

We can easily trace the axes using our set squares:

You must practise thistechnique until you are ableto do it without help.

On one of your pad’s pages, draw the three axes at120º and then draw this cube of 6 cm side.

First, draw everything softly

with your 2H pencil.

Then, outline all visible edges

with your 2B pencil (don’t

erase anything).

On one of yourpad’s pages,draw theseobjects.

Remember that theyare based on asmall 3cm sidecube.

First, draw everythingsoftly with your 2Hpencil.

Then, outline all visibleedges with your 2Bpencil (don’t eraseanything).

Your teacher will teach you the process you mustalways follow when you want to draw an isometricperspective. Learn and use this method, ALWAYS.

On a pad’s page, draw the three axes at 120º 7 times,using your set squares.

Then draw a sketch of all these pieces of furniture.

First, draw everything softly withyour 2H pencil.Then, outline all visible edges withyour 2B pencil (don’t erase anything).

Remember yourteacher’s method.

Draw this chair on a page of your drawing pad, usingyour set squares. Imagine the dimensions are inmm.

Don’t annotate!

First, draw everything softly withyour 2H pencil.Then, outline all visible edgeswith your 2B pencil (don’t eraseanything).

Remember yourteacher’s method.

Draw these object on a pad’s page in the isometricperspective, respecting the dimensions and usingyour set squares. Don’t annotate.

Remember yourteacher’s method.

Draw these object on a pad’s page in the isometricperspective, respecting the dimensions and usingyour set squares. Don’t annotate.

Then, draw the three flat views of the object at thesame scale.

The scale is the relation between the measurements ina drawing and the real measurements of a physicalobject.

S=1 Natural scale (1:1)

Objects are represented as they are, so there’s no confusion.

e>1 Enlargement scale

It’s used to draw small objects bigger than they are, so we canrepresent details (2:1, 10:1…).

To guess the real measurements,we’ll divide the size in the drawing by the scale.

e<1 Reduction scale

It’s used to represent big objects smaller than they are, sothey can fit the paper (1:75, 1:100, 1:1000, 1:10.000…).To guess the real measurements,we’llmultiply the size in the drawing by the scale.

Measurements in the planeScale =

Measurements in reality

What scale type would you use to represent…?

- A truck.

- A mobile phone.

- The roads net of a country.

- A pin.

- A screw.

- A house.

- A computer’s motherboard.

- The human body’s muscles.

- A dragonfly.

- A cell.

An area is represented on a 1:5.000 map. How manykilometers will separate two towns in the realterritory, if they are separated by 20 cm in the map?

We solve this using a rule of three:

DRAWING REALITY

1 cm in the map____________ 5.000 real cm

20 cm in the map___________ x real cm

x = 20 · 5.000 / 1= 100.000 cm = 1 km

Understand anduse this methodfor all theseproblems.

PAYATTENTION TOUNITS!!!!

What scale shall we use to represent a football pitchmeasuring 75 x 100 m so that it fits a Din-A3 paper(42 x 29,7 cm)?

We solve this by a rule of three, thinking of the longside of the paper and leaving a bit of free space:

DRAWING REALITY

1 cm in the plane____________ x real cm

38 cm in the plane___________ 10.000 real cm

x = 1 · 10.000 / 38= 263 cm

Escala: 1:300

When we want to choose the scale to represent a certain object on a plane, we must take intoaccount that there is a series of standardizedscales:

Reduction scales

Enlargementscales

Manufacturing and installations

Arquitecture, building and civil works

Topography and Geography

Urbanism