Any time that boards are cut from a log they are cut along the length (axis) of the log. This can be done in three ways: flat- or plain-sawing (most common), quarter-sawing (less common), or rift sawing (very rare.)
In plain sawing the log is passed through the blade cutting off plank after plank without changing the orientation of the blade or log. The resulting planks have different annual ring orientations when viewed from the end. The relative angle that form the rings and the surface go from almost zero degrees in the external planks to almost ninety degrees at log core.
Rift sawing is a technique of cutting boards from logs. Each board is cut along a radius of the original log, so that the saw cuts at right angles to the tree’s growth ring. This produces lumber of great stability. However, since this produces a great deal of waste (in the form of wedge-shaped scraps from between the boards) rift-sawing is much less-commonly used than flat sawing and quarter sawing.
Flat sawing produces the least waste, but produces boards which are more susceptible to warping and shrinkage, and which have a distinctive grain which may be esthetically undesirable for some uses. Quarter sawing produces more waste than flat sawing, but has a straighter grain, which in addition to being visually pleasing, makes the lumber more stable. Quartersawn wood is seen as an acceptable compromise between economical but less-stable flatsawn wood (which, especially in oak, will often display the distinct “cathedral window” grain) and the expensively-wasteful riftsawn wood, which has the straightest grain and thus the greatest stability.
Quarter-sawing gets its name from the fact that the log is first quartered lengthwise, resulting in wedges with a right angle ending at approximately the center of the original log. Each quarter is then cut separately by tipping it up on its point and sawing boards successively along the axis. That results in boards with the annual rings mostly perpendicular to the faces. Quarter sawing yields boards with straight striped grain lines, greater stability than flatsawn wood, and a distinctive ray and fleck figure. It also yields narrower boards, because the log is first quartered, and is more wasteful.
Quartersawn boards can also be produced by cutting a board from one flat face of the quarter, flipping the wedge onto the other flat face to cut the next board, and so on.