Source:http://www.bbc.co.uk/schools/gcsebitesize/design/resistantmaterials/processtechniquesrev1.shtml
Whether a product is being designed and made by you in school or by an international company, it is essential to have the right tools for the job. It is also essential to select the right materials, and to work out in advance which techniques and processes will be used to shape them.
Planning a sequence of work
Charts are used to plan out the use of time, and the stages in the making of the product. There are several different types of planning chart.
Gantt charts
Gantt charts are useful for planning complex projects. They show the tasks involved in making a product, with any overlaps between different tasks. Gantt charts usually use colour to indicate separate tasks or workflows.
Flowcharts
Flowcharts describe a sequence. All flowcharts use the same symbols, linked with arrows to show the direction of the flow.
- start and finish are rectangular with rounded corners
- process boxes are rectangular with square corners
- decision boxes are diamond shaped
Sequence diagrams
Sequence diagrams show the process of making a product in words and pictures.
Sequence diagram
- Use a small ball and cardboard to make the head.
- Draw a pattern for the puppet body shape and cut.
- Use string to make whiskers for the final touch.
Measuring and marking out
Measurements are taken from a baseline or datum surface. A lot of tasks require two datum surfaces at right angles to each other. Smoothing off will turn a rough, newly-sawn edge into a datum surface.
- To create a datum surface on wood, a plane is used.
- To create a datum surface on metal and plastics, a flat file or hand file is used.
A steel rule or straight edge is used to check that a surface is flat, and a try square is used to check a surface is at right angles to another surface.
Marking out
Marking out means the transfer of shapes and lines onto the material, as guides for cutting, bending or shaping them. Accurate marking out is essential if the different parts of the product are to fit together properly.
The correct marking-out tools for different materials
| Process | Wood | Metal | Plastics |
|---|---|---|---|
| Lines | Pencil | Scriber | Felt-tip pen |
| Lines at right angles to an edge | Carpenter’s try square | Engineer’s try square | Engineer’s try square |
| Lines parallel to an edge | Marking gauge | Odd-leg calipers | Odd-leg calipers |
| Marking for a mortise | Mortise gauge | N/A | N/A |
| Marking a circle | Pair of compasses | Dividers | Dividers |
| Marking the centre of a hole | Pencil | Centre punch | Felt-tip pen |
| Marking an irregular shape | Template | Template | Template |
