H to K of sawmill terminology

Glossary H – K

A-C   D-G   H   I   J   K   L-P   Q-S   T-Z


Generally, one of the botanical groups of deciduous trees that have vessels or pores and broad leaves. Hardwoods have traditionally been used in making such products as furniture, strip flooring, interior trim, cutting boards, novelties, and so forth. Generally more costly than wood from softwood species. Manufactured to non-standardized length and width dimensions to minimize trim waste. Lumber is measured relatively accurately, with rounding of measurements in small increments.

Harvest functions

  • Chipping – Breaking or cutting trees into small pieces of controlled fiber length.
  • Debarking – Removing the outer protective layer (bark) from trees or parts of trees.
  • Delimbing – Removing branches from trees.
  • Felling – Cutting or uprooting standing trees, causing them to fall as a result of the cutting or uprooting.
  • Forwarding – Transporting trees or parts of trees by carrying them completely off the ground rather than by pulling or dragging them along the ground. Also known as prehauling.
  • Loading – Picking up trees or parts of trees from the ground or from a vehicle, transporting them, and then piling them into another vehicle (such as a highway logging truck or rail car).
  • Skidding – Transporting trees or parts of trees by trailing or dragging them.
  • Slashing – Cutting felled and limbed trees into lengths. Also known as bucking.
  • Topping – Cutting off the top of a tree at a predetermined, minimum diameter.
  • Yarding – Initial hauling of a log from the stump to a collection point.
  • Harvesting – Removing merchantable trees (contrasts with cuttings, which remove immature trees).

Conveying wood from a loading point to an unloading point; The distance wood is transported

Head rig
Principal machine in a sawmill, used for the initial breakdown of logs by sawing along the grain. Logs are first cut into cants on the head rig before being sent on to other saws for further processing. Also known as head saw.

In a cross section of a log, the heartwood is the centre and dead portion where growth rings appear. This area, between the pith and sapwood may contain phenolic compounds, gums, resins and other material that usually make it darker and more decay resistant than sapwood.

A metric unit of area, 100 metres by 100 metres (10,000 square metres), or 2.471 acres.

High grade harvesting
A type of timber harvesting in which larger trees of commercially valuable species are removed with little regard for the quality, quantity, or distribution of trees and regeneration left on the site; often results when a diameter harvest is imposed.

High-lead logging
Wire rope system that involves yarding in logs or trees by means of a rope passing through a block at the top of the head spar.

Hi/Lo tracks
Fixed track positions where one track (Lo) sits on the ground, and the other (Hi) is raised. This prevents sawdust build-up on the track and allows logs to be rolled easily under the Hi track and into position.



One of a series of parallel beams used to support floor and ceiling loads and supported in turn by larger beams, girders or bearing walls.

Juvenile wood
Refers to wood formed early in the life of a tree. By most measures, juvenile wood is lower in quality than wood that forms later; this is particularly true of the softwoods. Juvenile wood shrinks and swells along the grain as moisture content changes. Strength is lower, and in some cases much lower, than mature wood of the same tree.


The width of the sawblade tips (circular or band) and the source of sawdust. The more traditional circular sawblades have tips with a wider kerf (1/4” to 3/8”) than the tips on new bandsaw blades (1/8” to 3/16”).

A chamber having controlled air-flow, temperature, and relative humidity for drying lumber. The temperature is increased as drying progresses, and the relative humidity is decreased. Freshly cut green lumber may be sold green or first dried in a kiln to accelerate removal of the moisture in the wood. Drying wood in a kiln is an art to ensure that the wood dries evenly to retain its strength and aesthetic properties. Different species dry at different rates. Kiln dried lumber commands a higher price than green or air-dried lumber.

Areas of the main stem of a tree in which the base of branch has been overgrown through diameter growth of the main stem. Knots in lumber or veneer are cross sections of tree branches.

A-C   D-G   H   I   J   K   L-P   Q-S   T-Z

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