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Graphic ProductsDrawing


Learning objectivesL

earn

ing

ob

ject

ives


To learn how to present designs using the following drawing techniques:

sketching

crating

perspective drawings

isometric drawings

working drawings (orthographic projections).

To learn how to enhance drawings using the following techniques:

3-tone rendering

thick and thin lines

hatching and textured effects.


Freehand sketching allows you to convey ideas very quickly. You should use sketching when drawing initial ideas or developing chosen designs.

Sketching is carried out without the use of drawing equipment such as rulers or rubbers.

The basic shape is drawn very lightly with

a pencil to allow for repeated corrections.

The shape is developed further

and begins to become more visible.

A bolder outline is drawn by applying greater

pressure. This draws the eye to the image.

Sketching


Crating


Drawing in 3D can be difficult to begin with.

There is a range of grid papers available to help you. The grid paper can be put under your working sheet to guide you.

The different styles of grid are designed to help you draw different types of drawing:

Squared grid Isometric grid

Grids and underlays


Perspective drawings give a sense of depth. There are two types: one point perspective

two point perspective.

A vanishing point This is positioned on the horizon line. The drawing is ‘pulled into’ the vanishing point.

A horizon line This is at eye level. It is the line at which the ground meets the sky.

Both types have similar characteristics and involve the following:

Perspective drawings


One point perspective drawings


Two point perspective drawings


There are two different styles of three dimensional drawing – oblique and isometric.

At GCSE you must become competent in isometric drawing.

This is how you draw an oblique projection:

You begin with a 2D

shape.

Then draw the same shape

again, offset from the original shape.

Connect the images together.

Oblique drawings are not the best way to present your ideas. They only show one side of the shape in any real detail.

Rub out the lines that cross

the image.

Isometric drawing


Then work away from the line,

drawing lines up at 30 degrees.

Connect the top two edges by working at 30

degrees again. They should meet exactly.

This drawing shows the shape in more detail

than the oblique projection.

This is how you draw an isometric projection:

Put the two side lines in, making sure

they are vertical.

Isometric drawing

Begin by drawing the centre edge of your

shape. Draw it vertically up the page.


Any shape can be drawn as an isometric projection. For complicated shapes, remember to use crating (mentioned earlier in this presentation) to ensure that your shapes have the correct proportions.

The ‘crate’ is drawn isometrically.

Isometric drawing


Working drawings are informational drawings – they give full details of an object’s size in 3D, and how its various parts are arranged.

All working drawings are done to scale so that they give an accurate representation.

Working drawings

Continuous thick line – outside edges

Dashed line – hidden detail

Chain line – centre lines

Continuous thin line – inside lines and dimension lines

Different lines are used for different parts of the drawing:


Orthographic projections give three views in one drawing. The views they show you are:

The views must be drawn perfectly in line with each other.

plan view

front view

side view.

Orthographic drawings

They have to follow British Standards in a number of ways.

Most working drawings are third angle orthographic projections.

They bear this symbol.


Orthographic projections must be drawn to British Standard requirements, as shown above.



Orthographic projections can be done by hand or on the computer.

Here is an example of a third angle orthographic projection done using ProDesktop.



3-tone rendering is a shading technique using three varying tones of colour. The tone depends on the amount of light hitting each part of the object.

The lightest tone is used where the light strikes the object most directly.

A medium tone is used for areas that get some light.

The darkest tone is used for areas that get very little light.

The position of the light source dictates which surface carries each tone.

3-tone rendering


3-tone rendering


You can enhance the images you draw to give them a more impressive and realistic finish.

The final outcome can vary greatly depending on the media used to render it. These are some possibilities.

Enhancement


You can create a more realistic 3D image by applying thick and thin lines to it.

A thick line is applied where you can only see one of the two connecting surfaces that make up the line.

A thin line is applied where both connecting surfaces that make up the line are visible.

Enhancement – thick and thin lines


Hatching is another way of rendering. It has three main uses:

Hatching is added with a pencil – a softer pencil is better if you want to vary the tone. You can also vary the density of the hatching.

to highlight key areas or hidden areas

to add a more three dimensional feel

to represent wastage.

Wastage (material to be removed)

Hidden area

Enhancement – hatching


Texture can be applied to objects to give the illusion of a surface finish. This can be used in presentation work to represent the materials the object will be manufactured from.

Texture can be added with a variety of mediums and using different styles and techniques.

Study the following textures and see if you can recreate them.

One of the easiest textures to apply using different shades of brown, orange and yellow. The grain effect is very easy to draw once the object has been shaded.

Wood

Enhancement – texture


MetalWhen applying a metal texture, remember your three tone shading. Build up the colour using grey and pale blue, then add reflective streaks as if the light is bouncing off the surface. You can do this using a white pencil or by rubbing out streaks of the base colour.

Plastic

Plastic is one of the more difficult textures to apply as it can be a very reflective surface. Use a technique similar to that of metal. Make sure the reflection lines follow the shape of the object.



Concrete

The easiest way to apply this texture is with a series of dots. Place the dots closer together to create dark areas and further apart to produce lighter areas. Try to make the surface look uneven.

Fabric

You need to create a soft effect, so avoid using straight lines drawn with a ruler. Soften the edges and apply bold colours using strokes in different directions to give a woven texture. You can also use lots of short pencil streaks to produce a furry effect.



Key pointsK

ey p

oin

ts


Rough images can be created quickly using sketching and crating.

3D objects can be drawn as one or two point perspective drawings, or as isometric drawings.

Designs can be presented formally as working drawings (orthographic projections).

Drawings can be enhanced using 3-tone rendering, thick and thin lines and textured effects.

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