Key Stage 3 design and technology · Make

KS3 design and technology: computer-aided manufacture (CAM)

Computer-aided manufacture, or CAM, means using a machine that is controlled by a computer file to cut, engrave or build a part. In Key Stage 3 design and technology, pupils design on screen and then use equipment such as a laser cutter, a 3-D printer or a vinyl cutter to make what they have drawn. The skill is not pressing a button: it is preparing a file that the machine can follow, and then checking, adjusting and improving the result.

Computer-aided manufacture, explained

The National Curriculum names computer-aided manufacture directly in the objective about using specialist tools and machinery precisely. It sits alongside computer-aided design, or CAD. CAD is the drawing stage: the pupil creates a shape on screen with exact dimensions. CAM is the making stage: that drawing is turned into instructions that a machine follows. Schools choose which machines they have, so your child might use a laser cutter, a 3-D printer, a vinyl cutter, a small computer-controlled router or an embroidery machine, and some may only use one or two of these.

Different machines work in different ways. A laser cutter uses a focused beam of light to cut through thin sheet material such as card, plywood or acrylic, or to engrave a surface by burning away a thin layer. It follows flat outlines, so it needs a vector drawing, made of lines and curves rather than coloured dots. A 3-D printer works the opposite way: it builds a part up in thin layers of melted plastic, following a 3-D model that has been sliced into layers by software. Because it adds material rather than taking it away, it can make shapes that are hard to cut, such as a hollow part with an internal channel.

Pupils learn that a machine only does what the file says. A line in the wrong place, two lines on top of each other, or a shape that is slightly too big will be cut faithfully, wasting material and time. Preparing the file therefore involves real decisions: drawing at full size (1:1), keeping lines closed so a shape is cut out completely, using one setting for cutting and another for engraving, and arranging parts close together on the sheet to waste as little material as possible. Teachers call this being precise, and it connects to the curriculum’s focus on communicating ideas with detailed plans and 3-D modelling.

Accuracy has limits too. A laser removes a thin strip of material as it cuts, called the kerf, which is a fraction of a millimetre. A slot drawn to fit a 3 mm sheet can come out slightly loose, so designers make a test piece and adjust the file. A 3-D print can shrink or warp as it cools, and its layers show as faint lines. Safety rules matter as well: a laser cutter is never left running unwatched, because the material can catch fire, and only materials approved by the teacher or technician are cut, because some plastics, such as PVC, give off harmful fumes. These checks are part of using the machines responsibly.

Finally, CAM does not replace hand skills. A laser-cut part may need sanding, gluing or painting, and a printed part may need supports removed. In industry, the same idea is used on a much larger scale, from cutting car body panels to printing medical parts, so the thinking pupils practise in school matches how many products are made.

Words your child will hear

CAD: Computer-aided design: drawing or modelling a design on a computer.
CAM: Computer-aided manufacture: using a computer-controlled machine to make the part.
Vector drawing: A drawing made of lines and curves described by numbers, which a laser cutter can follow exactly.
Kerf: The width of material a laser or saw removes as it cuts.
Additive manufacture: Building a part by adding material, layer by layer, as a 3-D printer does.
Infill: The pattern printed inside a 3-D printed part. A lower infill uses less plastic but makes the part weaker.
Nesting: Arranging parts tightly on a sheet so that as little material as possible is wasted.

What the National Curriculum says

The programme of study for Key Stage 3 says:

When designing and making, pupils should be taught to select from and use specialist tools, techniques, processes, equipment and machinery precisely, including computer-aided manufacture
When designing and making, pupils should be taught to develop and communicate design ideas using annotated sketches, detailed plans, 3-D and mathematical modelling, oral and digital presentations

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: preparing a laser-cut name tag and a printed part

A pupil wants a name tag cut from 3 mm sheet, with a hole for a lanyard, and a small 3-D printed clip. How do they prepare the files and check the results?

Draw the tag at full size in a vector drawing: an outline of 80 mm × 30 mm, a 6 mm circle for the lanyard hole, and the name as engraved text. Make sure the outline is a closed shape, with no gaps or duplicate lines.
Tell the machine what each line means. In most schools this is done by line colour or thickness: one setting means cut right through, another means engrave on the surface. The technician or teacher confirms which settings suit the material.
Test on scrap first. A cut-out tab that was drawn exactly 3 mm wide might fit a 3 mm slot loosely, because the laser removes a thin strip of material. The pupil adjusts the file by a fraction of a millimetre and tries again.
For the clip, check the print settings. The layer height is how thick each layer is, and smaller layers give a smoother part but take longer.
```
Part height: 40 mm
Layer height: 0.2 mm
Layers: 40 ÷ 0.2 = 200
At 0.1 mm: 40 ÷ 0.1 = 400 layers
```
Finish and evaluate. Remove the burn marks or supports, sand if needed, and check the parts against the plan. Record what to change in the file, such as a looser slot, a thicker wall or a lower infill, and make the improved version.

The finished tag matches the drawing because the file was precise, the settings were set for the right material and a test piece showed the fit needed adjusting. The clip prints in 200 layers at 0.2 mm, but would take roughly twice as long at 0.1 mm for a smoother finish.

Common mistakes and how to help

Believing the machine designs the part, or fixes mistakes in the drawing

A finished part appears at the touch of a button, so it can seem as though the computer did the clever thinking.

What helps: Point out that the machine copies the file exactly, including errors. Ask your child what they decided: size, material, line settings, layout. Those choices are the design.

Assuming a computer-controlled machine is perfectly accurate

Digital files have exact numbers, so pupils expect exact results. In reality the laser removes material, plastic shrinks as it cools and sheet thickness varies a little.

What helps: Encourage a test piece and a small adjustment before the final cut. Measuring the result with a ruler or calipers and comparing it with the file is a good habit.

Thinking a 3-D print is quick and free

Printers look simple, but even a small part can take hours, uses plastic and may fail halfway through if it is not set up well.

What helps: Work out print time and material together. Ask whether a smaller part, lower infill or a different process would meet the need with less waste.

Believing any material can go in the laser cutter

A laser cuts many things, so it seems reasonable to try whatever is to hand, including a scrap plastic from home.

What helps: Explain that some materials give off harmful fumes or catch fire, which is why only materials approved by the teacher or technician are used.

How to help at home

Draw to full size with exact measurements. Ask your child to draw a simple shape, such as a gift tag or a drinks mat, using a ruler and a compass, with every dimension marked in millimetres. Precise drawings are the first step towards a machine-ready file.
Test the fit with card. Cut two pieces of card and a slot for one to slide into the other. If it is loose or too tight, adjust the slot by half a millimetre and try again. It is the same method used with a laser cutter.
Spot how products were made. Look around the house for engraved patterns, laser-cut shapes on wooden or acrylic gifts and keyrings, or plastic parts with faint layer lines. Most everyday plastic items, such as phone cases, are moulded instead, so ask your child which process might have made each one and why.
Visit a place that has machines. Some libraries, museums and community workshops hold open days where visitors can see a 3-D printer or laser cutter at work. Watching one print in layers makes the idea clear.

Builds on

Key Stage 2: Using tools accurately
Key Stage 2: Choosing materials