Going Along With the Grain
Beautiful grain that makes wood so appealing to the eye can also make it difficult to work. Tear-out from planing, or splintery saw cuts, for instance, will spoil the look of any project. Taking time to read and understand the grain of a board before you start making project parts from it will help you machine it for top-quality cuts.
Why does wood have grain?
As trees grow they produce cells, which arrange themselves as fibers and water-conducting vessels. Some run vertically, others form radial structures (rays) outward from the center of the tree. Each year's cells create a cylinder of fibers—a growth ring—around the tree, from bottom to top.
Wood fibers resemble a package of uncooked spaghetti. But because we're talking about nature, things aren't neat and linear: Those fibers may twist and turn, growth rings vary in thickness from year to year, branches grow and create knots. Even the way the sawmill operator cuts a log into lumber directly affects a board's grain.
5 ways to follow the grain
To avoid tear-out, pay attention to the grain direction in relation to the cutting edge. Always move the tool along the wood or the wood across a cutter (such as when using a jointer) so the cutting edge doesn't dig under the fibers and lift them up. Here are five ways to judge grain direction.
1. Check the face grain and figure. You can usually determine grain orientation—the alignment of the grain along the board's surface—just by looking. (It's obvious in some species, such as walnut, oak, and mahogany.) Figure—the grain pattern—shows orientation, too. But even with magnification, it's difficult to judge the direction the grain runs in the board just by looking at the surface [Photo A]. Rely on other methods to be sure.
2. Feel the face. Find the grain direction simply by running your gloved hand or a shop rag along the board surface, following the grain orientation [Photo B]. If you feel snags and splinters, then you're moving against the grain.
3. Look around the corner. For a quick and accurate determination, check the grain orientation on the surface adjacent to the one you want to work [Photo C].
4. Check the end grain. Looking at a cathedral pattern in the grain, you might assume that the grain runs toward the point. That isn't always true; check the end grain to make sure [Photo D].
5. Try a cut. Slide a cornering tool, chisel, or even a sharp knife along a corner of the board. Watch for splinters, a sign you're going against the grain [Photo E].
When planing tears up your figured lumber, try a card scraper with a sharp burr edge instead. woodmagazine.com/ scraper
Remember, the cutting edge of a router, planer, or jointer turns against the direction of feed, and it can lift up and tear out a splinter when moving against the grain. When grain runs to an edge at a sharp angle [Photo B], tear-out becomes more likely. Visualize the cutting-edge movement in relation to the grain when it contacts the wood. Find out more about using hand planes.
Dealing with difficult grain
Sometimes the grain runs different directions on the same board [Photo F]. Highly figured boards may defy finding a consistent grain direction.
When the grain runs in two directions, hand-plane or rout to or from each end of the board to or from the point where the grain changes. Then, work that area with light cuts. Take a final light cut in the predominant grain direction. Angling the plane across the surface produces a shear cut that may provide some relief.
Planer and jointer techniques
Sharpen your jointer and planer knives to minimize tear-out. Take light cuts (about 1⁄64 ") in the principal grain direction the full length of the board, watching the results closely; turning the board end-for-end may give better results. Feed as slowly as you can without burning. If possible, run the workpiece through the machine at a slight angle.
A jointer or planer with a true helical or spiral cutterhead makes the cleanest cuts because it shears the wood at a skewed angle, compared to the head-on hit from straight knives. Although no benchtop planers come with such cutters, many 15" or larger planers do. Jointers 6" and larger often feature these cutters, and some manufacturers sell them to retrofit straight-knife jointers.
Support those fibers
Avoid splintered crosscuts and miter-cuts by supporting the fibers right up to the blade. Start with a zero-clearance throat insert in your tablesaw [Photo G]. (You can make a zero-clearance baseplate for a circular saw, too.) Another approach is to score the cutting line [Skill Builder].
To prevent edge tear-out on the tablesaw, attach an extension to your miter gauge, overhanging the end beyond the blade, and saw through it for a zero-clearance miter gauge [Photo H]. As a bonus, the kerf through the fence makes it easy to precisely line up your cut. Follow a similar strategy on the mitersaw [Photo I].
Similarly, installing a zero-clearance fence on your router table results in cleaner cuts, especially on complex profiles.
Scribe the cutting line for splinter-free sawing
Before making a crosscut or miter-cut, scribe with a marking knife the cutline on the bottom face and back edge (for a tablesaw; when using a circular saw, scribe the top face and front edge). By cutting the fibers right at the line, you'll prevent them from splintering back past the line as the blade breaks out of the board.