Metalwork: mark, cut, file, drill
Metalwork means shaping metal by hand tools or machines. The usual order is:
- Mark out the shape with a scriber and a steel rule. A scratched line is easy to see on metal.
- Cut with a hacksaw (hand) or a shear.
- File the rough edge smooth. Use a flat file for flat edges.
- Drill a hole. Clamp the metal first so it cannot spin, and punch a small dent where the drill must start.
Safety: wear goggles, tie back long hair, and file away from your body. Metals like mild steel are hard, aluminium is soft and light. Choose the metal for the job.
Woodwork: grain, planing and joints
Wood is made of long fibres. The direction of the fibres is the grain. A plank is strong when the load runs along the grain and splits when it is pushed across it.
Steps in woodwork: mark with a pencil and try-square, saw on the waste side of the line, plane the face smooth, chisel out any notch, then join. Common joints are the butt joint (nails or screws), the lap joint and the finger joint. A glued joint is often stronger than the wood next to it.
Hardwoods (teak, sal) are strong and costly. Softwoods (pine) are cheap and easy to cut.
Electronics: boards, parts and soldering
An electronic product has a circuit board. Thin copper lines (tracks) on the board act as wires. Parts such as a resistor, an LED and a battery are placed on it.
Soldering: a hot iron melts solder (a soft metal mix). The melted solder flows around the leg of a part and the copper pad, and sets into a shiny joint that holds the part and carries current. A good joint looks like a small shiny cone; a dull, round blob is a bad joint.
Always check the plus and minus of a battery and an LED. An LED put the wrong way round will not light.
Laser cutting and 3D printing (digital fabrication)
Digital fabrication means a computer file controls the machine. You draw the shape on a computer and the machine makes it.
- Laser cutting is subtractive: a narrow laser beam burns along the lines and removes material. Used for acrylic, wood, card, thin metal. Very exact and fast for flat shapes.
- 3D printing is additive: a nozzle melts plastic and builds the object in layers. It can make shapes that are hollow inside, which cutting cannot.
Both repeat the same shape again and again without tiring. Always check the file size and units (mm) before you send it to the machine.
Try it
At home, find five objects. For each, write which making process made it: metalwork, woodwork, electronics, laser cutting or 3D printing. Then use the layer slider in the last 3D step: guess the printing time for 20 layers, then check.
Key formulas and definitions
- Mark → Cut → File → Drill (metalwork order)
- Strong along the grain, weak across it (wood)
- Solder joint: iron heats the pad and the leg, then solder melts on them
- Subtractive: material removed (laser cutting). Additive: material added (3D printing)
- Print height = number of layers × layer height (e.g. 20 × 0.2 mm = 4 mm)
Worked examples
1. A school wants 30 identical acrylic name tags. Which process suits best, and why?
Laser cutting. A computer file repeats the same shape 30 times with the same size, and the laser is quick on flat acrylic. Cutting by hand would be slow and uneven.
2. A 3D print has layers of 0.2 mm. The object is 5 cm tall. How many layers?
5 cm = 50 mm. Layers = 50 ÷ 0.2 = 250 layers.
3. A wooden shelf bracket keeps cracking along one line. What may be wrong?
The grain runs across the part where the load acts, so the wood splits. Cut the bracket so the grain runs along the length that carries the load.
Common mistakes
- Cutting before marking: the line guides the saw, so mark first.
- Thinking laser cutting and 3D printing are the same: one removes material, the other adds it.
- Soldering a cold joint: if the iron does not heat both the pad and the leg, the joint looks dull and fails.
- Sawing exactly on the line: cut on the waste side, then file or plane to the line.