No More Tearout.
By: Chelsea Rodgers
The number one challenge in woodworking is avoiding tearout. Fortunately, it is fairly predictable if you know how to "read the grain." That refers to observing the grain pattern in a board and interpreting how its grain or tissue orientation will react when you are cutting it, especially in regards to planers and jointers, definitely when using hand planes.
When viewed from the end, a log's grain looks like a spider web (see the illustration at left). That grain as it presents in a board will tell you how it will react to cutting Those patterns (flat, rift and quartered) indicate where a board was harvested from a log. Riftsawn is the most difficult to predict which cutting direction will produce tearout.
Flatsawn lumber is the easiest grain to read, and also can tear out excessively if you try to "run the piece against the grain" through a planer or jointer. The growth rings in flatsawn stock are roughly parallel to the face, though they are curved. To joint or plane the faces, it's best to read the growth ring lines on the edge closest to the center of the tree. Woodworkers say that you always want to "cut uphill" on those lines. See the illustration above to clearly understand what that means. All machines cut against feed direction, meaning that you must be aware of the rotation of the cutter head when using a jointer or planer. To mill the edges, read the direction of the rays on the face. Read them near the center of the cathedral patterns and remember that you should never read the cathedrals themselves.
Quartersawn stock is the opposite of flatsawn, in that the growth rings run perpendicular to the face. Again, think of a spider web, where the concentric rings are like growth rings and the radial lines are like the rays. So evaluate quartersawn stock in the opposite way to flatsawn stock. To cut the faces, look at the edges. The edge closest to the center will have tiny cathedral patterns (if properly quartersawn), but read the tiny rays running through them instead. To mill the edges, read the growth ring lines on the faces. Look to the bottom illustrations to understand the proper feed direction and cutter rotation.
On riftsawn boards where the growth rings on the end grain are 45 degrees to the faces and edges everywhere, it's more difficult. In that case, read both rays and growth rings on both faces and edges. Where rays and growth rings run the same direction, you’ll read the grain
correctly for sure. Where they run in opposite directions, you're really just flipping a coin. Try light cutting in one direction to see how the wood behaves.
'Worth the Effort
The fact is that we always have a 50/50 chance of making the right or wrong choice, but that does not reduce the value of reading the grain. Incorrect feed direction can and will cause tearout at the worst possible time. So just because some stock may be hard to read correctly doesn't mean we should abandon the practice altogether.
Now, let’s talk about situations where the grain reverses direction once or twice or even more in a single board. In this case, the best course is to cut according to what the largest amount of the grain indicates is the best feed direction. And where you observe that you have grain that twists profoundly or reverses within the length of the board, use extremely shallow cutting passes (and extremely sharp cutting edges).
Some high-figure grain patterns, such as bird's-eye and curly figure (e.g., maple) involve constantly reversing grain, and there is often no risk-free way to proceed. Quilted maple, crotch-grained mahogany and waterfall bubinga are some other grain patterns that will present this problem. Shallow cutting passes will be helpful, but shifting to scraping or sanding methods (including thickness sanders) will be most successful.
Reading the grain will save you time and frustration. It is something every woodworker should learn to do. The good news is that you will get better at it as you work on it.