Materials: solid wood and manufactured boards
Solid wood
- Softwood comes from conifers (needle-leaf trees): pine, spruce, cedar. Usually lighter, cheaper, easy to work.
- Hardwood comes from broad-leaf trees: oak, maple, teak, sheesham, walnut. Usually denser, stronger, better for fine furniture.
- "Hard" and "soft" name the tree type, not always the real hardness. Balsa is a hardwood but very soft.
Wood has grain (the direction of its fibres). It is strongest along the grain and splits easily along it. Wood shrinks and swells with moisture, mostly across the grain, so it must be dried (seasoned) to about 8–12% moisture for indoor use.
Grades
Lumber is graded by how many defects it has (knots, splits, warp, wane). Higher grades have long clear pieces and cost more. Common terms: rough sawn (straight from the mill), S4S (surfaced four sides, ready to use), nominal vs actual size.
Manufactured (engineered) boards
- Plywood: thin veneers glued with grain at right angles. Stable and strong in all directions.
- MDF: fine fibres + glue pressed flat. Smooth, takes paint well, heavy, weak with water and screws in the edge.
- Particle board: chips + glue; cheap, often covered with melamine.
- Newer materials: bamboo board, laminated veneer lumber, solid-surface and composite panels.
Tools, equipment and safety
- Measuring and marking: tape measure, steel rule, try square, combination square, marking gauge, pencil and marking knife.
- Hand tools: saws (rip, crosscut, tenon), chisels, planes, mallet, rasps, screwdrivers, clamps.
- Power tools and machines: table saw, mitre saw, band saw, jointer, thickness planer, router, drill press, sanders, CNC router.
Safety rules
- Wear eye and ear protection and a dust mask; no loose clothes, tie long hair.
- Use push sticks and blade guards; keep hands well away from the blade.
- Unplug a machine before changing a blade or bit.
- Keep the floor clear and collect dust: fine wood dust is a health and fire risk.
Working drawings, planning and maths
A working drawing shows the project in orthographic views (front, top, side) plus details. Conventions: thick visible lines, dashed hidden lines, thin centre lines, dimensions in millimetres, a scale (e.g. 1:10) and a title block. From it you make a cut list (each part, size, quantity, material).
Useful maths
- Volume = length × width × thickness (m³).
- Mass = volume × density (pine ≈ 500 kg/m³, oak ≈ 720 kg/m³).
- Kerf: each cut removes the blade width (≈ 3 mm). n parts from one board need n − 1 cuts.
- Sheet layout: a standard sheet is 2440 × 1220 mm. Plan parts to waste the least.
- Units: 1 inch = 25.4 mm, so 3/4 in = 0.75 × 25.4 = 19.05 mm. Some countries still sell lumber in board feet (1 board foot = 12 in × 12 in × 1 in).
- Screws: a screw should go about two-thirds into the second piece; its length ≈ thickness of first piece + 2/3 of the second.
- Cost = quantity × unit price + 10–15% for waste.
Before you cut, lay out all parts with square, gauge and knife. If a design must change (a wider shelf, a different wood), update the drawing and the cut list first.
Processes: cutting, joining, assembly and quality
A logical order: mill the stock flat and square → cut to size → cut the joinery → dry-fit → glue and clamp → sand → finish → install hardware.
Common joints
- Butt: two ends meet; needs screws or dowels.
- Rabbet (rebate): a step on an edge; used for cabinet backs.
- Dado (housing): a groove across a board; holds shelves.
- Mortise and tenon: a tongue in a hole; tables and chairs.
- Dovetail: interlocking tails and pins; drawers. Strong and decorative.
- Biscuit, dowel, pocket screw: quick modern methods.
Joints are structural (they hold load) and can also be decorative (visible dovetails, contrasting pegs).
Cabinet terms
Carcass (the box), face frame, frameless (European) cabinet, toe kick, door styles (slab, shaker/frame-and-panel), hinges (butt, concealed), drawer slides, shelf pins, edge banding.
Quality control
Check each part against the drawing: tolerance about ±0.5 mm, square corners (equal diagonals), flat surfaces, tight joints. Install cabinets level and fixed into studs or wall plugs.
Finishing
- Prepare: fill holes, then sand with the grain from coarse to fine grit (80 → 120 → 180 or 220). Remove all dust.
- Colour (optional): stain or dye.
- Protect: oil (easy, natural look), shellac, lacquer, varnish or polyurethane (hard, waterproof), water-based finishes (low smell), wax, or paint (good on MDF).
- Apply thin coats; lightly sand between coats.
Work in a ventilated space. Oily rags can catch fire by themselves: lay them flat to dry or keep them in water.
Try it: take a scrap board. Sand one half only with 80 grit and the other with 80 → 120 → 180. Wipe a drop of water on both. Feel and look: which is smoother?
Key formulas and definitions
- Volume (m³) = length × width × thickness (all in metres)
- Mass (kg) = volume × density
- Cuts needed for n parts in a row = n − 1; total kerf loss = (n − 1) × kerf
- 1 inch = 25.4 mm; 1 foot = 304.8 mm
- Screw length ≈ first piece thickness + 2/3 of second piece thickness
- Material cost ≈ quantity × unit price × 1.1 to 1.15 (waste allowance)
Worked examples
1. A pine shelf is 900 mm × 250 mm × 18 mm. Find its volume and mass (pine ≈ 500 kg/m³).
V = 0.9 × 0.25 × 0.018 = 0.00405 m³. Mass = 0.00405 × 500 = 2.025 ≈ 2.0 kg.
2. You cut 4 equal parts from a 1200 mm board with a 3 mm kerf. How long is each part?
4 parts need 3 cuts. Loss = 3 × 3 = 9 mm. Wood left = 1200 − 9 = 1191 mm. Each = 1191 ÷ 4 = 297.75 mm.
3. A plan says 3/4 inch thick. What is that in mm?
3/4 = 0.75. 0.75 × 25.4 = 19.05 mm. The nearest common metric board is 18 mm or 19 mm.
4. You screw an 18 mm side into a 19 mm shelf edge. About how long should the screw be?
18 + 2/3 × 19 ≈ 18 + 12.7 = 30.7 mm, so use a 30 mm screw.
5. A cabinet needs 3.2 m² of plywood. A sheet is 2.44 m × 1.22 m and costs 40 units. Allow 15% waste. How many sheets and what cost?
Sheet area = 2.977 m². Needed with waste = 3.2 × 1.15 = 3.68 m². Sheets = 3.68 ÷ 2.977 ≈ 1.24 → buy 2 sheets. Cost = 2 × 40 = 80 units.
6. Your cabinet diagonals measure 1012 mm and 1018 mm. Is it square? What do you do?
No. A square box has equal diagonals. Push the long diagonal corners together (or re-set the clamps) until both read about 1015 mm, then let the glue dry.
Common mistakes
- Cutting on the line or on the wrong side and forgetting the kerf, so parts come out 3 mm short.
- Gluing end grain in a butt joint and expecting it to hold: end grain glues poorly.
- Skipping grits when sanding (80 straight to 220), which leaves scratches that show under the finish.
- Using machines without guards or push sticks, or changing a blade without unplugging.