Graphic Expression and Communication
Student workbook · 4 sessions · Colegio Reina Sofía · Totana
Technical Documents, Pencils & Paper
Sections 1 & 2 of the unit
In engineering and architecture, a technical project is made up of plans, diagrams and texts that define the production and assembly of the object.
All the documents and drawings for a technical project should have certain features and elements to ensure they can be read and understood clearly:
- There is always a large margin between the drawing and the edge of the paper. It varies, but it is usually at least 8 mm from the edge of the sheet.
- We include a title block with information about the drawing. It is usually located at the bottom of the sheet of paper, or on the right-hand side of larger sheets, so that it can be read when the sheet is folded up.
| Title block | What it tells us |
|---|---|
| Title | What exactly is represented in the drawing. |
| Project | The name of the project. |
| Draftperson | The person who is responsible for the drawing and for the information in it. |
| Date | When the drawing was finished. |
| Version | Drawings are sometimes revised during the design process; we indicate the version and the drawing that was changed. |
| Scale | The size of the drawing relative to the real object. It can be numerical or graphic. |
Paper size. We usually use A4 format. It belongs to the most common paper format in Europe, DIN (a German institute for standardisation). Each A format is half the length of the long side of the previous format.
Pencils. Pencils are made of wood with lead in the centre. The lead is made of graphite and clay, which are baked and mixed with oil. The hardness of the lead depends on the amount of graphite. The most common types are:
- Soft pencils have the letter B. They are good for artistic drawing because they are softer and the lines are thicker. The softest is 6B.
- Hard pencils have the letter H. They make a thinner, cleaner and more exact line, so we use them for technical drawing. The hardest is 6H.
- An HB pencil is in the middle of the hardness scale and is appropriate for general use.
For technical drawing we also use markers of different width, colour and ink type (for different surfaces) and drafting pens with different nibs for drawing with ink.
Paper. There are many types of paper and they are just as important as the right pencil. We choose one or another according to the type of drawing and the effect we are looking for.
Paper weight is expressed in g/m²: we calculate the weight of a square metre of that paper. This gives us an idea of its thickness and resistance. For example, silk paper is 20 g/m² and card is 120 g/m². The paper in a notebook is between 60 and 80 g/m².
Paper finish is the appearance and feel of the paper:
| Group | Finish | Meaning |
|---|---|---|
| Shine | Matte | No shine |
| Gloss | Shiny | |
| Texture | Smooth | No texture |
| Textured | Grainy, lined or rough | |
| Colour | Coloured | Dyed or printed |
| Transparent | Film |
White is the most common colour. The paper we are going to use in class is white, smooth, matte and DIN A4.
Key vocabulary
- margin
- title block
- draftperson
- version
- scale
- graphite
- lead
- hard pencil
- soft pencil
- drafting pen
- nib
- paper weight
- matte
- gloss
- smooth
- textured
1. Multiple choice
Choose the correct answer for each question, then press Check.
2. Drag and drop
Drag each word into the correct box. (On a tablet you can also tap an item and then tap its box.)
3. Fill in the gap
Complete each sentence with a word from the bank. Tap a gap, then tap a word (or type it).
Get ready on your device — your teacher is going to launch a live quiz about everything you've just learnt. Answer fast and carefully!
Design your title block: on a sheet of A4 paper, draw a margin of 8 mm and a title block with its six parts (Title, Project, Draftperson, Date, Version, Scale). Fill it in for a project of your own.
Sketches, Diagrams, Plans & Drawing Tools
Sections 3 & 4 of the unit
There are three ways to represent an idea on paper, and each one gives us more information than the one before.
3.1. Sketches. A sketch is a freehand drawing of the mental image we have of an object. It gives us a basic idea of what the object, or the answer to a technical problem, looks like. Before we do a sketch, we need to know exactly what we want to present: we have to know the features and details of the object. Sketches don’t have to be totally accurate and we can include graphic elements (for instance, arrows).
3.2. Diagrams. A diagram is a more detailed representation of the idea in a sketch. It can still be a freehand drawing, but it is more accurate and it gives us the measurements of the object. A diagram should have general measurements of the object and each piece, an approximate scale, the materials it is made of and the way the pieces are joined.
3.3. Plans / technical drawings. A technical drawing includes the same information as a diagram, but it is drawn using tools (including computer-aided design, CAD) so that it is more precise. We can take measurements from it because it is drawn to scale. We can only make technical drawings when we know exactly what the dimensions and features are.
4. Basic measuring and drawing tools
| Tool | What it is and what we use it for |
|---|---|
| 4.1. Ruler | A strip of wood or other material with a straight edge, usually marked off in centimetres with a decimal point for the millimetres. It is used for drawing lines and measuring. |
| 4.2. Protractor | It is used for measuring angles. It is a semicircle of plastic with lines to indicate angles. |
| 4.3.1. Triangle | A right-angle isosceles triangle with one angle of 90° and two of 45°. We use it with the set square to draw parallel and perpendicular lines and to make angles. |
| 4.3.2. Set square | A right-angle scalene triangle: the three sides are not the same length (the hypotenuse is twice the length of the shortest side). Its angles measure 90°, 60° and 30°. |
| 4.4. Compass | We use it to draw circumferences or arcs and to transport segments. The space between the two points of the compass is the radius of the circle. |
Key vocabulary
- sketch
- freehand
- features
- arrows
- diagram
- technical drawing
- plan
- CAD
- to scale
- ruler
- protractor
- triangle
- set square
- compass
- radius
- angle
1. Multiple choice
Choose the correct answer for each question, then press Check.
2. Drag and drop
Drag each feature into the correct box. (On a tablet you can also tap an item and then tap its box.)
3. Fill in the gap
Complete each sentence with a word from the bank. Tap a gap, then tap a word (or type it).
Get ready on your device — your teacher is going to launch a live quiz about everything you've just learnt. Answer fast and carefully!
Sketch & improve: choose a small object from your pencil case. Make a freehand sketch of it, then turn it into a diagram by adding its general measurements and the materials it is made of.
Scale
Section 5 of the unit
We don’t usually draw objects the same size as they actually are in real life. It is impossible and not very practical to make a life-size drawing of a house or a tiny wheel in a watch.
We usually enlarge or reduce the dimensions proportionally: we increase or decrease all the parts equally. In a scale drawing all the angles are the same, but the lines are different, yet in proportion.
The scale of a drawing is the relationship between the size of the object in the drawing and the object in real life.
Choosing the scale. The choice of scale for a drawing depends on three factors:
- The real size of the object.
- The size of the paper on which the drawing is made.
- The level of detail that we need in the drawing.
As a general rule, we want to get the highest possible level of detail. The only condition is that it should fit on the paper. We can divide the length of the longest part of the object by the length of the paper.
Graphic scale. A graphic scale is a line marked at intervals on a drawing or map. Each interval on the line represents a certain distance in reality, so that you use the lengths on the line to measure real distances.
Scale ruler. It is a triangular measuring instrument with six different sides/scales.
How to read a numerical scale. In the figure above, 1:2 means the drawing is smaller than the real object (a reduction), and 2:1 means the drawing is bigger than the real object (an enlargement).
Key vocabulary
- scale
- enlarge
- reduce
- proportion
- angle
- real size
- level of detail
- graphic scale
- interval
- scale ruler
- reduction
- enlargement
1. Multiple choice
Choose the correct answer for each question, then press Check.
2. Drag and drop
Drag each item into the correct box. (On a tablet you can also tap an item and then tap its box.)
3. Fill in the gap
Complete each sentence with a word from the bank. Tap a gap, then tap a word (or type it).
Get ready on your device — your teacher is going to launch a live quiz about everything you've just learnt. Answer fast and carefully!
Scale challenge: measure your pencil case. Choose a scale so that its longest side fits on an A4 sheet with an 8 mm margin, and write the scale you chose in a title block.
Standardisation & Annotation
Sections 6 & 7 of the unit
6. Standardisation. Technical standardisation is the set of rules that bring together and regulate aspects of technical drawing like the types of lines, symbols, scales and perspectives. Everybody who reads the drawing understands it in the same way.
| Name | Style | Function |
|---|---|---|
| Edge | Indicates a separation between planes. | |
| Hidden edge | Indicates an edge that cannot be seen. | |
| Cut | Indicates a cut in the object. | |
| Axis | Represents the axis of a circle. | |
| Section | Shows an area which has been cut away. |
7. Annotation. Annotation means we put the real measurements of an object on the drawing to make it easier to read and understand. To annotate we must follow certain rules and use specific elements.
7.1. Annotation rules
- Dimension elements must be thinner.
- Avoid using the edges of an object to annotate.
- Numbers must be in the centre and in the same style.
- If the arrows don’t fit, they must go outside.
- Annotations must go outside the pieces.
- The diameters of circles are shown above an arrow connecting the edges and passing through the centre point.
7.2. Annotation elements. Look how annotations are shown on this diagram:
| Element | What it is |
|---|---|
| Symbols | We write these before a number to show a special dimension that is not a straight edge. Diameter: Ø Radius: R Square: □ |
| Leader line | It shows a note explaining something on a drawing: a number, text, etc. |
| Projection line | A line perpendicular to two dimension lines. It shows the extremities (the furthest points) of a dimension. We draw it 2 mm in from the end of the dimension lines. |
| Dimension line | A line parallel to and the same length as the edge of the object. These lines are always placed outside of the object. |
| Dimension | The number that shows the real measurement of the object in millimetres. We write all measurements in the centre of the line, parallel to a horizontal or vertical line. |
| Symbols at the end of the dimension lines | These are usually arrow points. |
Key vocabulary
- standardisation
- edge
- hidden edge
- cut
- axis
- section
- annotation
- dimension
- dimension line
- projection line
- leader line
- diameter
- radius
- arrow
1. Multiple choice
Choose the correct answer for each question, then press Check.
2. Drag and drop
Drag each item into the correct type of line. (On a tablet you can also tap an item and then tap its box.)
3. Fill in the gap
Complete each sentence with a word from the bank. Tap a gap, then tap a word (or type it).
Get ready on your device — your teacher is going to launch a live quiz about everything you've just learnt. Answer fast and carefully!
Spot the mistakes: your teacher draws an object with 3 annotation mistakes on the board. In pairs, find them, say which rule is broken and explain how to correct it, in English.