Timber & Cutting Glossary: 30 Trade Terms With Units

One page, thirty terms, every unit stated exactly as the trade uses it. Definitions are written to be quoted: two to three sentences, the conversion included, no fluff. Use the anchors below to jump, or search the term with your browser.

Kerf: The slot of material a blade removes as it cuts — the part that becomes sawdust. Typical values: 2–3.5 mm for circular saw blades, 1–1.5 mm for bandsaws, under 1 mm for laser and waterjet. Every cutting plan must add one kerf width between adjacent parts.
Guillotine cut: A straight cut that runs from one edge of the sheet to the opposite edge, dividing it completely — the way a guillotine, panel saw or glass cutter works. Guillotine-constrained layouts are simpler to produce but waste more than free nesting; all linear and glass cutting is guillotine by nature.
Nesting: Arranging parts on a sheet to minimise waste, especially with irregular shapes (CNC nesting). Contrast with guillotine cutting, where every cut must cross the full sheet. Better nesting shows up directly as a higher yield per sheet.
Offcut: The usable leftover piece after a cutting plan executes. Good planning treats offcuts as inventory — tracked, measurable, and reused in a later plan — rather than as waste. A warehouse full of untracked offcuts is money that cannot be spent.
Board foot (BF): The North American lumber volume unit: 1 BF = 144 in³ = 0.00236 m³ (nominal 1 × 12 × 12 inches). Prices per MBF (1,000 BF = 2.36 m³) convert to metric by dividing: 500 $/MBF ≈ 212 $/m³.
Stere (st): One cubic metre of stacked firewood or roundwood, air gaps included. Solid content runs 0.65–0.75 for clean straight wood, so 1 stere ≈ 0.7 solid m³ — always ask whether a price refers to stacked or solid volume.
Cord: The North American firewood stack: 4 × 4 × 8 feet = 128 ft³ = 3.62 m³ stacked, typically 2.4–2.7 m³ solid. A face cord (rick) is one row of that stack and has no single standard depth.
Raummeter (rm): The German stacked-volume unit for firewood and roundwood: one cubic metre of stacked space including gaps. Equivalent to the stere; compare Festmeter for the solid counterpart.
Festmeter (fm): The German solid-volume unit: one cubic metre of actual wood with no air gaps. 1 fm ≈ 1.4–1.55 rm at typical stacking factors — the difference between the two is pure air, and pricing confuses them at its peril.
FBM / MBF: Feet board measure: lumber volume in board feet, quoted per thousand (MBF = 1,000 BF = 2.36 m³). The standard price unit of North American lumber trade; convert to $/m³ before comparing with metric quotes.
Hoppus foot (h ft³): The quarter-girth log unit: h ft³ = (girth/4)² × length ÷ 144. Reads ≈ 78.5% of true volume by design (allowance for sawing); 1 h ft³ ≈ 0.0361 true m³, 50 h ft³ = 1 Hoppus ton ≈ 1.80 m³.
Log rule: A formula or table estimating the board feet of lumber a log will yield — Doyle, Scribner and International ¼-inch being the classic three. Each embeds different taper and kerf assumptions, so the same log scales differently under each rule.
Fibre saturation point (FSP): The moisture content (≈ 28–30%, about 22% for the teak group) at which cell cavities are empty but cell walls remain saturated. Below FSP wood starts shrinking; above it, moisture moves without dimensional change.
Moisture content (MC): Water in wood as a percentage of oven-dry mass: MC = (wet mass − oven-dry mass) ÷ oven-dry mass × 100. On this dry basis fresh wood can exceed 100% — the water can outweigh the dry cell-wall material.
Equilibrium moisture content (EMC): The MC wood finally settles at for a given humidity and temperature: roughly 6–10% in heated interiors, higher outdoors. Wood dried above its service EMC will shrink in use — the root cause of gaps and loose joints.
Shrinkage (radial / tangential / volumetric): Dimensional change from green to oven-dry, expressed in percent. Tangential shrinkage runs about twice the radial (commonly 6–12% vs 3–6% green to OD), which is why flatsawn boards cup; volumetric sums the effect.
Sticker: A dry, uniform spacer stick laid between layers of lumber in a drying stack so air can flow over every board. Sticker spacing, alignment and quality decide drying speed and sticker-stain risk.
Planing allowance: Extra thickness and width left on rough-sawn timber so it can surface cleanly: nominal 1 in (4/4) rough finishes around ¾ in (19–21 mm) after planing. Buy rough dimensions with the finished size plus allowance in mind.
Stowage factor (SF): Cargo volume divided by cargo mass, m³ per tonne, including dunnage and voids: SF = volume ÷ tonnes. Low SF = dense cargo, weight-bound; high SF = light cargo, space-bound. IMO CSS Code Table 4.1 lists reference ranges for wood cargo (sawn wood 1.8–3.8 m³/t).
Cube-out / weigh-out: The two ways a container or hold fills first: by space (cube-out) or by weight (weigh-out). The decider is balanced density — payload ÷ usable volume (≈ 1.0 t/m³ in a 20GP, ≈ 0.46 in a 40GP, ≈ 0.39 in a 40HC) — against the cargo's density.
Recovery rate: Sawn lumber volume out divided by roundwood volume in, times 100. FAO global average ≈ 50%; EU softwood mills 46–50%, hardwood 36–40%. The single best number for judging a saw line's efficiency.
Overrun: Actual lumber yield minus the log rule's estimate, as a percentage of the estimate. Positive overrun usually means the rule underestimates (Doyle on small logs can overrun +30–100%), not that the mill performed heroics.
Gauge: A sheet-thickness number in which bigger means thinner. There is no single standard — steel, galvanized, stainless, aluminium and wire each have their own table — so a gauge number without a material is ambiguous.
Sheet metal gauge (MSG): The Manufacturer's Standard Gauge for plain sheet steel: 16 gauge = 1.52 mm, 14 gauge = 1.90 mm, 20 gauge = 0.91 mm, weight ≈ 7.85 kg per m² per mm. Galvanised and aluminium use different tables for the same gauge numbers.
Pattern repeat: The vertical distance after which a wallpaper pattern lines up again. Straight-match papers waste little; drop (half-drop) matches shift every second strip and force one extra repeat of trim per strip — the main driver of wallpaper waste.
Double roll: The North American wallpaper packaging unit: two single rolls in one continuous package, 27 in × 27 ft ≈ 60.75 sq ft ≈ 5.6 m². Pricing per single roll but shipping per double roll is the classic ordering trap.
Spring angle: The angle at which crown moulding sits away from the wall or ceiling — commonly 38° or 45°. It feeds the compound miter and bevel settings: same moulding, different spring angle, different saw settings.
Sphere rule: In compound mitre work, the saw settings for joints arranged around a body can be derived by treating the joint as cuts on a sphere — the geometry behind standard tables that turn wall corner angle plus spring angle into miter and bevel settings.
Feeds & speeds (vc, vf, fz): The machining trio: cutting speed vc at the tool edge (m/min), feed rate vf of the table (mm/min), and feed per tooth fz (mm). Spindle speed n ties them together — n = vc × 1000 ÷ (π × d) — and all four move as one system.
Cutting stock problem: The optimisation problem of cutting stock items from standard-size material at minimum waste: one-dimensional (bars, profiles) or two-dimensional (sheets, guillotine or freeform). Every cutting calculator on this site is a practical approximation of it.