How Timber is Sawn

A tree falls in the forest. Within hours it arrives at the sawmill as a log — round, tapered, full of moisture, and hiding its character inside. What happens next determines everything: the grain pattern you see, the stability of the board, the yield from the log, and the cost of the timber. Sawing is where raw material becomes usable wood.

In Track 1 (Guide 10 — How Logs Become Boards), we introduced the idea that different sawing methods produce different boards. In Track 2, we learned that tangential and radial orientation determines how much a board moves. In Track 3, we saw how species properties interact with board orientation to create stability, cupping, and distortion. This guide goes deeper into the sawing process itself: the machines, the methods, the decisions the sawyer makes, and why those decisions affect every piece of timber you'll ever buy.

From Log to Board: The Basic Process

The conversion of a round log into rectangular boards involves a series of decisions and cuts:

1. Debarking — The bark is removed, often mechanically. Bark damages saw blades and has no value as sawn timber (though it's used for mulch, fuel, and growing media).
2. Log assessment — The sawyer evaluates the log: diameter, taper, sweep (curvature), visible defects, species. This determines the sawing pattern.
3. Primary breakdown — The first cuts that convert the round log into rough boards, cants, or flitches. This is where the sawing pattern is established.
4. Resawing — Cants and flitches are further cut into finished-dimension boards.
5. Edging — Waney (bark-edged) boards are trimmed to give straight, parallel edges.
6. Trimming — Boards are cut to length, removing defective ends.
7. Grading and sorting — Boards are assessed for quality and sorted by grade, species, and dimension. The critical step is primary breakdown — the sawing pattern chosen here determines the grain orientation, appearance, and behaviour of every board that comes from the log.

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Sawing Patterns

There are three fundamental sawing patterns, each producing boards with different characteristics. Understanding these is essential for selecting timber and predicting how it will behave.

Through-and-through (plain sawing / flat sawing)

The simplest and most common method. The log is cut into parallel slices from one side to the other. How it works:

• The log is clamped to the carriage and passed through the saw
• Each pass removes one board
• The saw cuts parallel planes through the log What it produces:
• Boards near the centre have growth rings roughly perpendicular to the face — these are effectively quarter-sawn
• Boards away from the centre have growth rings roughly parallel to the face — these are plain-sawn (flat-sawn)
• Most boards from a through-and-through cut are plain-sawn Advantages:
• Maximum yield — very little waste. The log is used almost entirely.
• Fast — minimal log handling. The log stays in one orientation.
• Simple — requires the least decision-making and equipment.
• Cost-effective — the cheapest conversion method per cubic metre of output. Disadvantages:
• Most boards are plain-sawn, meaning:
  • Higher tangential movement on the face
  • Greater tendency to cup
  • No medullary ray figure (in species like oak)
• Board widths taper with the log
• Boards from near the pith may contain the boxed heart — the weak, unstable centre of the log

Quarter sawing

The log is first split into quarters (or the sawing pattern is arranged to approximate this), and each quarter is sawn so that the growth rings are approximately perpendicular to the board face (60–90° to the face). How it works (true quarter sawing):

• The log is cut into four quarters through the pith
• Each quarter is sawn with the cut faces alternating to keep the rings as close to perpendicular as possible
• The quarter must be repositioned between cuts What it produces:
• Boards where the growth rings meet the face at 60–90°
• The radial face is presented to the surface
• In ring-porous species like oak, the medullary rays are displayed as distinctive ray fleck (also called silver grain or tiger stripe) Advantages:
• Much more stable — movement across the face is radial (the lesser direction). Boards cup less and move more predictably.
• Better appearance in some species — the ray fleck in oak is highly prized. Rift and quarter-sawn oak commands a premium.
• More consistent wear — in flooring, the radial face wears more evenly
• Less tendency to warp, twist, or bow Disadvantages:
• Lower yield — significantly more waste than through-and-through. The geometry of cutting quarters means many narrow, tapering offcuts.
• Slower — the log or quarter must be repositioned multiple times.
• Narrower boards — board width is limited by the radius of the log, not the diameter.
• More expensive — the combination of lower yield and slower processing increases cost substantially. Quarter-sawn boards typically cost 30–80% more than plain-sawn from the same species.

Rift sawing

Rift-sawn boards have growth rings at 30–60° to the face. In practice, rift-sawn boards are often produced as a byproduct of quarter sawing, or by specific cutting patterns designed to maximise the number of boards in this orientation. What it produces:

• Boards with a straight, even grain pattern — no cathedral arches (plain-sawn) and no ray fleck (quarter-sawn)
• A clean, uniform appearance favoured in modern and minimalist design
• Stability between plain-sawn and quarter-sawn In practice:
• True rift sawing (all boards at 30–60°) produces the lowest yield of any method and is therefore the most expensive
• Most "rift-sawn" timber is produced alongside quarter-sawn as part of a mixed cut
• Rift-and-quarter-sawn packs contain a mix of both orientations

Live sawing (sawing around)

A variation of through-and-through where the log is rotated 90° between passes, so cuts are made from all four sides. How it works:

• One or more boards are cut from one face
• The log is rotated 90°
• One or more boards are cut from the new face
• Repeat until the remaining cant is sawn through-and-through What it produces:
• A higher proportion of boards with ring angles between 30° and 90° compared to straight through-and-through
• The outer boards from each face are closer to quarter-sawn
• Better average stability than plain through-and-through, with a yield closer to through-and-through than quarter sawing This is a common commercial compromise — better quality than straight through-and-through, without the yield penalty of true quarter sawing.

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Comparing Sawing Patterns

**Method**	**Ring angle to face**	**Yield**	**Stability**	**Cost**	**Best for**
Through-and-through	0–90° (mixed)	Highest	Variable (mostly plain-sawn)	Lowest	Structural, general purpose, cost-sensitive work
Quarter-sawn	60–90°	Low	Excellent	Highest	Fine furniture, flooring, instruments, joinery
Rift-sawn	30–60°	Lowest	Good	Very high	Modern furniture, uniform-grain applications
Live sawing	0–90° (better mix)	High	Moderate (better average)	Moderate	Commercial hardwood, improved quality at reasonable yield

--- ## The Machines: How Logs Are Cut Different types of saws are used depending on the operation, the log size, and the required precision. ### Bandsaw (band mill) The most common primary breakdown saw worldwide. - A continuous steel band with teeth runs over two large wheels - The blade is thin (1.5–3 mm typical kerf) — **less waste** per cut than circular saws - Available as **horizontal band mills** (log stationary, blade moves) and **vertical band mills** (log moves through stationary blade) - Can handle large diameter logs - Portable band mills (e.g., Wood-Mizer, Lucas Mill) have made small-scale sawmilling accessible **Advantages:** Thin kerf (high yield), handles large logs, versatile, relatively low cost. **Disadvantages:** Blade wanders in dense or knotty timber, requires frequent blade changes and sharpening, slower than circular saws for high-volume work. ### Circular saw Used for primary breakdown in high-volume mills and for resawing and edging. - A large-diameter circular blade (up to 1.5 m+) spins at high speed - Thicker kerf than bandsaws (3–6 mm typical) — more waste per cut - Very fast and powerful — suited to high-throughput production - **Twin circular saws** (one above, one below the log) can cut logs that exceed the radius of a single blade **Advantages:** Fast, powerful, consistent cut quality, less blade wander than bandsaws. **Disadvantages:** Thicker kerf (more waste), limited by blade diameter for log size, higher energy consumption. ### Frame saw (gang saw / sash saw) A traditional European saw still used in some high-volume mills. - Multiple parallel blades are mounted in a frame that reciprocates (moves up and down) - The log or cant is fed through the frame, and **all boards are cut simultaneously** in a single pass - Extremely efficient for high-volume production of standard dimensions **Advantages:** Very high throughput, consistent thickness across all boards, thin kerf possible. **Disadvantages:** Inflexible — all cuts are parallel and at fixed spacing. Cannot optimise for individual log characteristics. High capital cost. ### Chainsaw mill The simplest and most portable option. - A chainsaw is guided along a rail or jig clamped to the log - Used for on-site milling, slabbing large logs, and remote locations where other equipment can't reach - Wide kerf (6–10 mm) — significant waste - Slow and labour-intensive **Advantages:** Portable, low capital cost, can mill logs where they fall. **Disadvantages:** Wide kerf, slow, rough surface, physically demanding, inconsistent thickness. ### Optimising saws (modern production mills) Modern high-volume sawmills use computer-controlled systems: - **3D laser scanning** of each log before cutting - **Computer optimisation** calculates the cutting pattern that maximises value from each log - Automated positioning and feed systems execute the optimised pattern - Some mills combine **profiling heads** (chipping heads that shape the log into a cant) with circular or band saws for final breakdown These systems can increase value recovery by **10–20%** compared to manual decision-making, and they're the standard in large commercial softwood and hardwood mills. --- ## Kerf: The Hidden Cost Every saw cut removes material. The width of the cut is called the **kerf**, and it represents timber that becomes sawdust rather than boards.

**Saw type**	**Typical kerf (mm)**	**Waste impact**
Thin-kerf bandsaw	1.5–2.0	Low — maximises yield
Standard bandsaw	2.0–3.0	Low to moderate
Circular saw	3.0–6.0	Moderate to high
Frame saw	2.0–3.5	Low to moderate
Chainsaw mill	6.0–10.0	High

In a log producing 20 boards, each additional millimetre of kerf wastes roughly **20 mm of total log width** — nearly an extra board in some cases. This is why thin-kerf bandsaws dominate where yield matters (hardwood milling, expensive species), while thicker-kerf circular saws dominate where speed matters (high-volume softwood production). --- ## What the Sawyer Decides The sawyer's job is deceptively complex. For every log, decisions must be made about: ### Orientation Which way does the first cut go? The sawyer reads the log — its taper, sweep, visible defects, and sometimes the end grain — to decide the optimal orientation. - A log with sweep (curvature) is positioned so the curve is vertical, allowing the saw to follow the curve and produce longer boards - A log with a visible defect on one face may be turned so that face produces the first cut (a low-value slab), preserving the clear wood for better boards ### Sawing pattern Through-and-through for speed and yield? Quarter-sawn for value? Live-sawn as a compromise? This depends on: - **Species** — oak is often quarter-sawn for the ray fleck premium. Pine is almost always through-and-through for cost efficiency. - **Market** — what dimensions and grades are in demand? - **Log quality** — a high-quality butt log may justify the yield loss of quarter sawing. A small, knotty log is best sawn through-and-through to maximise recovery. ### Board thickness The sawyer selects target thicknesses based on market demand. Common nominal thicknesses: - **Softwood:** 19 mm, 22 mm, 25 mm, 38 mm, 47 mm, 50 mm, 75 mm - **Hardwood:** 25 mm (1"), 32 mm (1¼"), 38 mm (1½"), 50 mm (2"), 63 mm (2½"), 75 mm (3") Thicker boards are more valuable per cubic metre but yield fewer boards per log. The sawyer balances thickness against demand. ### Allowance for shrinkage Green timber shrinks as it dries. Boards must be sawn **oversize** to allow for this: - A board intended to finish at 25 mm after drying might be sawn at 27–30 mm green - The exact allowance depends on species (shrinkage rate), thickness, and whether the board will be kiln-dried or air-dried - Insufficient allowance means the dried board is undersize and may be downgraded --- ## Yield: How Much of the Log Becomes Boards? Log-to-board yield varies enormously depending on the log, the sawing pattern, and the equipment: - **Through-and-through, softwood, good log:** 55–65% board recovery - **Through-and-through, hardwood, average log:** 45–55% - **Quarter-sawn, hardwood:** 35–45% - **Rift-sawn:** 25–35% The remainder becomes: - **Sawdust** (kerf waste) — 10–15% - **Slabs and edgings** (the rounded outer cuts) — 15–25% - **Defect trim** — 5–10% None of this is truly wasted in a modern mill. Slabs and edgings are chipped for paper pulp or particleboard. Sawdust is used for MDF, animal bedding, or biomass fuel. Bark is composted or burned for energy. --- ## Reading Board Character from the Sawing Pattern As a buyer or maker, you can read the sawing pattern from the board: ### End grain tells the story Look at the end of the board: - **Growth rings roughly parallel to the wide face** → **Plain-sawn.** Expect cathedral arch grain on the face. Higher tangential movement. Will cup toward the bark side. - **Growth rings roughly perpendicular to the wide face** → **Quarter-sawn.** Expect straight, parallel grain lines on the face. Ray fleck visible in oak and similar species. More stable. - **Growth rings at 30–60°** → **Rift-sawn.** Straight grain, no ray fleck, moderate stability. ### Face grain tells you too - **Cathedral arches** (pointed ovals) on the face → plain-sawn - **Straight, parallel lines** → quarter or rift-sawn - **Ray fleck** (shimmering ribbon-like patches) → quarter-sawn, in species with prominent rays (oak, beech, sycamore, lacewood)

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Sawmilling and Timber Quality

The quality of the sawing directly affects the quality of the timber you receive:

Thickness consistency

Poorly maintained saws or worn guides produce boards that vary in thickness. This means more material must be removed during planing to achieve a flat, consistent surface — reducing the final dimension.

Surface quality

Bandsaws produce a rougher surface than circular saws. This doesn't matter for timber that will be planed, but it affects drying rate (rougher surfaces dry faster but less evenly) and visual assessment during grading.

Blade wander

Bandsaw blades can deflect (wander) when cutting through hard knots, dense heartwood, or reaction wood. This produces boards with uneven thickness — thicker on one side than the other. Skilled operators and well-maintained equipment minimise this.

Sawing stress

The act of sawing releases internal stresses in the log (covered in Track 2, Guide 9). A board may bend, bow, or spring immediately after being cut. This is normal and expected — it's the released growth stress in the tree. The sawyer can sometimes anticipate this and adjust, but it's often unavoidable.

Sawing and the Timber Supply Chain

Understanding how sawmills operate helps you navigate the timber market:

• Structural softwood is almost always through-and-through sawn, kiln-dried to target MC, and machine-graded. You buy by strength class and dimension.
• Hardwood is often sold "fresh-sawn" (green) or air-dried in sawn sizes, with the buyer responsible for further drying and machining. Understanding the sawing pattern helps you select boards that suit your application.
• Specialist cuts (quarter-sawn oak, rift-sawn white oak for whisky barrels) are available from specialist suppliers at a significant premium.
• Portable mill timber from small-scale operators may have variable thickness and quality. Inspect carefully and allow for more waste in processing.

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Media and Image Recommendations

1. Diagram: the four sawing patterns
   • Cross-sections of a log showing through-and-through, quarter-sawn, rift-sawn, and live-sawn cut lines, with the resulting board orientations highlighted
2. Photo: a bandsaw mill in operation
   • Showing the log on the carriage, the blade, and boards being stacked
3. Photo: end grain of plain-sawn vs quarter-sawn boards
   • Side-by-side showing the ring orientation clearly
4. Diagram: kerf waste comparison
   • Visual showing the same log cut with a thin-kerf bandsaw vs a wide-kerf circular saw, highlighting the extra board recovered with thinner kerf
5. Photo: medullary ray fleck in quarter-sawn oak
   • The distinctive silver grain that makes quarter-sawn oak so valued

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The Key Idea

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What's Next

In Guide 2 — Air Drying Timber, we follow the freshly sawn boards to the drying yard. Green timber must lose most of its moisture before it can be used — and the simplest, oldest, and still widely practised method is air drying. We'll cover how it works, how long it takes, what can go wrong, and when it's the right choice.

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Species Pages

• European Oak — often quarter-sawn for ray fleck premium
• Pine / Spruce — through-and-through sawn for cost efficiency
• Douglas Fir — larger structural dimensions, available in high strength classes
• Larch — resinous, resin bleed risk during processing

Glossary Terms

• Kerf
• Through-and-Through (Plain Sawing)
• Quarter Sawing
• Rift Sawing
• Live Sawing
• Bandsaw (Band Mill)
• Circular Saw
• Frame Saw (Gang Saw)
• Cant
• Flitch
• Waney Edge
• Debarking
• Boxed Heart
• Resaw
• Slab

Calculators

• None for this guide

Related Guides

• Fact-Check Report — Guide 1: How Timber is Sawn