Quartersawn and flatsawn: What's the difference?
Quartersawing is like cutting the log into pie shaped quarters and either cutting smaller wedges or rotating to cut parallel to the prior cut, to get one board.
The other method, which only yields a partial radial cut, is to cut the pie shaped quarter up parallel to the radius.
The type of cut depends on your purpose. Certain joints, such as a miter joint, are best made with radial cut lumber.
The end results can be interesting visually (quartersawn oak, for instance) or structurally, as in vertical grained boards, and so on.
Pick up some boards and look at the end grain. If the growth rings are parallel to the width of the board, it is flatsawn. If the growth rings are perpendicular to the width of the board, it is quartersawn. In softwood, it is usually called vertical grain.
Usually when I need quartersawn, I buy rift and quartered, which is cost and materials conscious. You get some with growth rings at 90 degrees to the width of the board, and some with the growth rings at a slight angle to the width of the board. Rift is sometimes called comb grain, as if you dragged a comb with paint on it along the length of the board and made vertical lines on it.
It is not unusual to see rift sawn as ring angles of 75 to 90 degrees to the wide faces, quartersawn as 45 to 75, and still showing figure. Plain or flatsawn can be 0 to 45 degrees. However, some sources, such as the US Forest Service, call 45 to 90 degrees quartersawn. The NHLA says quartersawn is wood that shows the pronounced ray fleck--I like this as it means that appearance is what counts.
Gene Wengert, forum technical advisor
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