Tip #66
How to Read Wood Grain
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Aside from proper machine setup, the most important aspect of planing wood is reading the wood grain and knowing the characteristics of the wood. By misreading the wood grain, or misfeeding a board, the planer can ruin wood faster than any other tool in your shop.

It may sound a bit strange, but planing wood is a lot like petting a cat. If you stroke the fur in the wrong direction, it'll stand up and look awful. But if you stroke the fur in the direction it lays, the fur stays flat and smooth.

Fig. 1

Like the fur on a cat, wood grain generally lays in one direction. And, as planer knives rotate, they must stroke the wood in that same direction (see Fig. 1). This is called feeding the wood with the grain.

If you feed a board with the grain running in the wrong direction, of feed it too fast for the grain pattern, the knives will dig under the annual rings and tear out chunks of wood. Instead of cutting a smooth surface, the planer leaves the board torn, chipped, and rougher than when you began planing. The general rule for feeding a board into the planer is simply that “the knives should stroke the wood, not ruffle its fur”.

The nature of wood grain is determined by several factors; the annual rings; how the board was cut; from what part of the tree the board was cut; and other natural phenomena such as curls, burls, and bird's eyes.

Fig. 2

You must be able to recognize all of these qualities before you plane any board.

To determine general grain direction, look at the edge of the board perpendicular to the face you want to plane. If the grain is obscured by mill marks or rough sawing, join or hand plane the edge (see Fig. 2). Look down the edge of the board for the lines created by the annual rings. These lines will show you the general direction of the grain.

Fig. 3

You'll notice that the annual ring lines will either follow an edge or lead off toward one face or the other. Wavy grain my lead first to one face, then curve back to the other (see Fig. 3). Look for the general direction these lines take. This will determine the direction that you should feed the board into the planer.

Finding the general grain direction is just the first stem. A board may also have knows, crotch figuring, burls, bird's eyes, or a curly grain pattern. Some boards may even have two or more of these characteristics, and each must be taken into consideration.

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