Flat Sawing

Flat Sawing

Flat (plain) sawing is performed by cutting planks from a log without changing the orientation of either the blade or the log. Cuts are therefore made in parallell to a tangent of the log, whose angle in relation to the log's growth rings ranges from almost 0 degrees for exterior boards, to almost 90 degrees near the log's core. Cutting the log in this way results in either a vertical, or easily identifiable cathedral grain as seen in the example to the left. In addition to producing the widest boards, plain sawing is the least wasteful, and hence most economical technique used for cutting logs. Due to the minimal waste factor associated with flat sawn lumber, it is the most commonly used method for lumber manufacturing. Despite these benefits, plain sawn lumber is also the least structurally sound, with an increased propensity for warping, shrinking, twisting, cupping, checking, and splitting. Softwoods cut in this way are referred to as "flat-grained".

Quarter Sawing

Quarter sawing involves quartering a log lengthwise, and subsequently cutting planks from each quartered section at angles of between 45 and 90 degree to its annual growth rings. Due to the associated waste factor, quarter sawing is more expensive than plain sawing, and produces narrower boards. Quarter sawing has the benefit of reducing warping, shrinking, twisting, cupping, checking, and splitting, yeilding more structurally sound boards than those which are plain sawn. Quarter sawing also produces a vertical grain that is more aesthetically pleasing in some species. However, quarter sawing exposes medullary rays in certain species (particularly oak), resulting in the flake effect seen to the left. For this reason, oak is sometimes rift sawn to minimize flaking, and produce a vertical grain more comparable to other quartered species. Softwoods cut using a similar technique are referred to as "edge-grained".

Rift Sawing

Rift Sawing

Rift sawing is a technique typically used on species such as oak, which may possess heavy medullary ray growth. When rift sawing, the log is cut along its radius, such that cuts are made at right angles to the log's growth rings. Rift sawing results in an accentuated vertical grain superior to that of quarter sawing, with minimal medullary ray exposure. The rift sawn white oak board displayed to the left illustrates this uniform vertical grain, without the flaking effect created by quarter sawing. Rift sawing produces the most structurally stable boards, however, it is the most wasteful, and therefore least economical method used to cut lumber. For those species that do not exibit a heavy medullary ray growth, quarter sawing is an acceptable compromise between efficiently produced, but less stable flat sawn lumber, and wasteful, but sturdier, and potentially more aesthetically pleasing rift sawn lumber.

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