Timber Products and Furniture

If your focus area is Timber Products and Furniture, Sections I and II of your written paper are about this industry: 10 multiple-choice marks and about 15 marks of short answers (roughly six items, at least one worth 4–6 marks). Together they are worth 25 of the 40 written marks. The questions test Industry Related Manufacturing Technology: the materials, tools, machines and processes of the timber and furniture industry, with WHS, design and costing applied to them.

• Timber as a material: hardwoods and softwoods, tree structure, sapwood and heartwood, Australian species, moisture content, seasoning, shrinkage and defects, durability and preservative treatment.
• Conversion and manufactured boards: back-sawn and quarter-sawn boards, veneer cutting, plywood, particleboard, MDF, hardboard and engineered timber (LVL, glulam, CLT).
• Joining: traditional joints, knockdown fittings, cabinet hardware and adhesives.
• Finishing: surface preparation, abrasives and finishes (oils, polyurethanes, lacquers, stains).
• Machines and processes: dressing timber, CNC and CAD/CAM, jigs and batch production, safe operating procedures.
• Design, management and calculations: ergonomics, costing by lineal metre, volume and area, moisture content calculations.

Section II questions often ask you to calculate (show every step), describe a process in sequence, or explain why a material or process is chosen. Name things with correct industry terms.

Hardwoods come from broadleaved flowering trees (angiosperms), such as eucalypts. Softwoods come from conifers (gymnosperms), such as radiata pine and hoop pine. The names are botanical: balsa is a hardwood but very soft. Hardwoods have vessels (pores); softwoods are made mostly of tracheids.

A trunk has an outer band of sapwood, which carries sap and stores starch, and inner heartwood, which is dead and holds extractives. Heartwood is usually darker and more durable. The starch in hardwood sapwood is food for lyctid (powderpost) borers, so lyctid-susceptible sapwood is treated or limited in use.

Common Australian timbers:

Moisture content

Moisture content (MC) is the mass of water as a percentage of the oven-dry mass:

Worked example: a sample weighs 84.0 g wet and 70.0 g oven-dry.

Always divide by the oven-dry mass. The oven-dry mass of a board stays the same while it dries, so you can use it to find the board's mass at any other MC (mass = oven-dry mass × (1 + MC/100)).

Green timber holds free water in its cell cavities and bound water in its cell walls. When the free water has gone but the walls are still saturated, the timber is at fibre saturation point (about 25–30% MC). Below this point timber shrinks and gets stronger. In service, timber settles at its equilibrium moisture content (EMC), which matches the humidity of the surrounding air. Furniture timber is dried to the EMC of the place it will be used, usually lower for air-conditioned interiors.

Shrinkage and conversion

Timber shrinks most tangentially (along the growth rings), about half as much radially, and hardly at all longitudinally. That difference causes distortion.

• Back-sawn (flat-sawn) boards have growth rings roughly parallel to the face. They are cheaper, show 'cathedral' figure, but shrink more in width and tend to cup.
• Quarter-sawn boards have rings at about 60–90° to the face. They are more stable and less likely to cup, but they give more waste and cost more.

Seasoning and defects

Seasoning dries timber to a suitable MC. Air drying stacks boards outdoors with stickers between layers; it is cheap but slow and can only reach the EMC of outdoor air. Kiln drying controls temperature, humidity and air flow to a schedule. It is faster and reaches lower MCs, but uses energy and must be carefully controlled. Solar and dehumidification kilns are variations.

Durability and treatment

Natural durability is the resistance of heartwood to decay and insects, rated in classes 1 (most durable) to 4, with separate ratings above ground and in ground. Spotted gum, for example, is class 1 above ground and class 2 in ground. Less durable timbers, especially pine, are pressure treated. The hazard level system matches treatment to exposure:

Manufactured boards are made from veneers, particles or fibres bonded with adhesive. They are stable, come in large flat sheets (often 2400 × 1200 mm) and use small logs and residues.

• Plywood: an odd number of veneers glued with the grain of each layer at right angles, balanced about the centre ply, so it is stable and strong in both directions. Veneers are usually rotary peeled: a softened log turns against a long knife to give a continuous sheet. Decorative veneers are sliced (flat or quarter) into separate leaves.
• Particleboard: wood chips bonded with resin; cheap, flat, often melamine-faced. Moisture-resistant (MR) grades are dyed green and used in kitchens and bathrooms.
• MDF: wood fibres bonded under heat and pressure; uniform, grain-free, machines and paints well; poor edge screw-holding and swells if wet.
• Hardboard: thin, dense fibreboard for drawer bottoms and cabinet backs.
• LVL, glulam and CLT: structural engineered timber. LVL and glulam have their grain running parallel (beams), while CLT has layers glued at right angles (wall and floor panels).

Most boards use formaldehyde-based resins. Low-emission boards are labelled E1 or E0. Their benefits are better use of each log; their drawbacks are the resin emissions and how hard they are to recycle.

Joints

Knockdown fittings and hardware

Knockdown (KD) fittings join panels mechanically so furniture can be flat-packed: cam locks, cross dowels with barrel nuts, KD blocks and confirmat screws. Cabinets use concealed (European) hinges, sold as full overlay (the door covers the side completely), half overlay (two doors share one side) and inset (the door sits inside the opening). The 32 mm system bores rows of holes at 32 mm centres so all the hardware fits standard positions, which suits CNC batch production.

Adhesives

Sand from coarse to fine grits (higher number = finer), for example 120 → 180 → 240, removing the scratches of each grit before moving on. Remove dust before finishing.

• Penetrating finishes (tung oil, Danish oil, decking oil) soak in, look natural and are easy to repair, but give less protection.
• Film finishes (polyurethane, lacquer, shellac) build a hard surface layer that resists water, heat and wear, but are harder to repair. Outdoors, films crack and peel in sunlight.
• Water-based finishes release fewer volatile organic compounds (VOCs) than solvent-based ones.
• Stains colour timber but do not protect it.

Finish quantity is calculated by area, number of coats and coverage. Worked example: two cabinet doors, each 0.70 m × 0.45 m, get two coats on the front face only, with coverage of 10 m² per litre.

To dress rough-sawn timber (dressed all round, DAR):

1. Jointer (buzzer): flatten the face side.
2. Jointer: plane the face edge square to it.
3. Thicknesser: plane the opposite face parallel, to thickness.
4. Table saw: rip to width, then plane the sawn edge.
5. Docking saw: cut to length.

Other key machines: the panel saw (sheet goods), bandsaw (curves, resawing), router and spindle moulder (profiles), edgebander, wide-belt sander and CNC router.

CAD/CAM and CNC: designs drawn in CAD produce cutting lists; CAM creates toolpaths and nests parts on sheets to cut waste; the CNC router cuts, bores and grooves automatically. Benefits include accuracy, repeatability, speed, less waste and mass customisation. Drawbacks are high capital cost, the need for new skills and fewer manual jobs.

Types of production: one-off (custom, made to order), batch (a set number of identical items) and mass production (continuous, high volume). Quality control checks parts against the drawing and tolerances during and after production.

Other processes: laminating (gluing thin strips over a former to make curved parts), steam bending (softening solid timber with steam and bending it around a form), wood turning on a lathe, veneering panels in a press, and upholstery. Portable power tools (drills, routers, biscuit joiners, sanders) and hand tools (chisels, planes, marking gauges) are still used for fitting and finishing.

Jigs and templates guide tools or hold work so every part in a batch is identical and interchangeable. They make batch production faster and safer, with no repeated marking out.

WHS in the workshop

Major hazards include contact with cutters, kickback on saws (controlled by the riving knife, guards and push sticks), wood dust (a known carcinogen, controlled by dust extraction, an engineering control, plus respirators), noise, solvent fumes from finishes, and manual handling of sheets. Apply the hierarchy of control (elimination, substitution, isolation, engineering, administrative, PPE) and follow safe operating procedures. Use Safety Data Sheets for finishes and adhesives.

Ergonomics fits products to users. Anthropometric data (body measurements, such as popliteal height and seated elbow height) set seat and desk heights, often designing for the 5th to 95th percentile or making parts adjustable. Solid timber tops must be fixed with buttons or slotted fasteners so they can move across the grain.

Costing methods:

• Lineal metre: cost = total length × price per metre (add a waste allowance).
• Volume: cost = length × width × thickness (all in metres) × price per m³.
• Unit cost: materials + labour (hours × rate); selling price = cost × (1 + mark-up).

Worked example: 4 lengths of 1.2 m at $12.50 per lineal metre, plus 10% waste.

• Dividing moisture content by the wet mass instead of the oven-dry mass.
• Leaving millimetres unconverted in volume calculations (convert to metres first).
• Forgetting the number of coats in finish calculations, or the waste allowance.
• Calling every timber 'hardwood' or 'softwood' by its hardness.
• Mixing up cupping, bowing and springing.
• Saying the thicknesser flattens a twisted board. It only makes faces parallel; the jointer flattens.
• Answering WHS questions with 'wear PPE' only. Name the hazard and match a specific, higher-level control.
• Writing dot-point lists for 'describe' questions. Describe each stage in sentences.

• Identify (1 mark) needs a correct industry term. Outline needs a brief sketch. Describe needs the features or stages in order. Explain needs cause and effect ('because…', 'so…'). Compare needs similarities and differences. Evaluate needs a judgement against criteria.
• In calculations, write the formula, substitute, include units and give the final answer clearly. Marks are given for correct working even if the final answer is wrong.
• For process questions (kiln drying, plywood, dressing timber), number the steps in your head and write them in sequence.
• Use specific materials and products: 'MR particleboard with melamine face', not just 'board'.
• In the 4–6 mark item, plan two or three developed points and end with a judgement if the verb asks for one.

• Industry Study (Section III): your timber knowledge is your evidence. Use examples such as CNC routers, dust extraction, certified timber, the Timber Industry Award 2020 and cabinet-making apprenticeships.
• Major Project: the same materials, joints and finishes appear in your folio; the written exam rewards the same correct terminology.