Tip #66 How To Read Wood GrainA GuideTo Better Planing

Aside from proper machinesetup, the most important aspect ofplaning wood is reading the woodgrain and knowing the characteris-tics of the wood. By misreading thewood grain, or misfeeding a board,the planer can ruin wood faster thanany other tool in your shop.

It may sound a bit strange, butplaning wood is a lot like petting acat. If you stroke the fur in thewrong direction, it'll stand up andlook awful. But if you stroke thefur in the direction it lays, the furstays flat and smooth.

Like the fur on a cat, woodgrain generally lays in one direction.And, as planer knives rotate, theymust stroke the wood in that samedirection (see Fig. 1). This is calledfeeding the wood with the grain.

If you feed a board with thegrain running in the wrong direc-tion, of feed it too fast for the grainpattern, the knives will dig underthe annual rings and tear outchunks of wood. Instead of cuttinga smooth surface, the planer leavesthe board torn, chipped, androugher than when you beganplaning. The general rule for feed-ing a board into the planer is simplythat "the knives should stroke thewood, not ruffle its fur".

The nature of wood grain is

determined by several factors; theannual rings; how the board wascut; from what part of the tree theboard was cut; and other naturalphenomena such as curls, burls, andbird's eyes.

You must be able to recognizeall of these qualities before youplane any board.

To determine general graindirection, look at the edge of theboard perpendicular to the face youwant to plane. If the grain is ob-scured by mill marks or roughsawing, join or hand plane the edge(see Fig. 2). Look down the edgeof the board for the lines created bythe annual rings. These lines willshow you the general direction ofthe grain.

Fig. 1Fig. 2

You'll notice that the annualring lines will either follow an edgeor lead off toward one face or theother. Wavy grain my lead first toone face, then curve back to theother (see Fig. 3). Look for thegeneral direction these lines take.This will determine the directionthat you should feed the board intothe planer.

Finding the general graindirection is just the first stem. Aboard may also have knows, crotchfiguring, burls, bird's eyes, or a

curly grain pattern. Some boardsmay even have two or more ofthese characteristics, and each mustbe taken into consideration.

Knots are extremely hard andthe grain within each knot runs atan angle to grain in the surroundingwood. This angle may be slight or itmay be nearly perpendicular to theoverall grain direction. To avoidtearing a knot, feed the board sothe planer knives 'stroke' the grain.

Crotch figuring is the transitionbetween the knot and the woodaround it. It's not as hard as theknot, but it's harder than the sur-rounding straight grained wood.(The grain pattern is highly figured-- erratic and wavy -- but it followsone general direction.) Feed thewood so the knives stroke in thisdirection (see Fig. 4).

Fig. 3

Fig. 4

Burls are hard, dense clusters ofundeveloped knots surrounded byfigured wood similar to crotchfiguring. The gain direction istotally random. Because of this,burls are extremely difficult toplane. Take very shallow cuts at avery slow feed rate (see Fig. 5).

Bird's eyes are tiny knots,similar to the center of a burl,randomly distributed throughout aboard. The grain of bird's eyes alltend to follow the same direction.This will determine how you feedthe board into the planer (see Fig.6).

A curly grain pattern grows inpronounced waves that follow ageneral direction through the board.Because the waves are so exagger-ated, the board may be difficult toplane. Feed the board in the direc-tion indicated by the general graindirection and take very shallow cutsat a slow feed rate (see Fig. 7).

Since many types of grain mayexist in a single board, the overallgrain direction may be completelydifferent at each end. If you have aboard like this, "reading" the grain

can be more art than science.Look at the entire board and

average out the effects of thedifferent gain patterns. Do yourbest to determine the feed direction.Then make the first pass with avery shallow depth of cut at theslowest feed rate. If the board chipsor tears, reverse the feed directionand try again. If the board stilltears, check your planer knives foralignment and sharpness. Shaperknives and precise setup are abso-lutely essential for best results.

Once you're getting goodresults on one side of the board,you're ready to start planing theother side. But don't panic! Thesecond side is always easier thanthe first. Just flip the board over,turn it end-for-end, and feed itthrough using the same planersettings.

Fig. 5

Fig. 6

Fig. 7

Mahogany,African (crotch)

Elm, Carpathian (burl-round)

Maple (bird’s eye -- half-round)

Pine, White(plain sliced --knotty)

Pine, South-ern Yellow(plain sliced)