Apr 6, 2009

Reading and understanding wood grain.

Understanding wood grain.
(any picture is clickable for a full view)

One of the most common mistakes people make in a woodshop is feeding the wood into the machine in the wrong direction. They don't understand the grain of the wood and often times find themselves chipping or gouging out grain when running a router, shaper, or planer. First of all wood grain is a form of natural organic growth. As we all know anything that grows, does so in a pattern. And natural patterns, if not followed, normally lead to problems. Lets go with an example of a cats fur. When you pet a cat front to back it's fur is nice and smooth. The hair lays down over each other with a very natural pattern. Now stroke him backwards, what do you get? Ruffled up hair standing straight up on end, in a ugly not so nice pattern, with a cat half mad.

The anatomy of wood cell structure:

I couldn't explain this better. This is an excerpt from wood magazine. Detailed information on the pores and structure of wood cells.
Technically, the word grain refers to the orientation of wood-cell fibers. That's quite different from figure, which describes the distinctive pattern that frequently results from various grain orientations. To understand this, it may help to think of the word direction following the word grain. All grain types except straight grain can be a blessing or a curse. Because wood with anything other than straight grain may be sawn to produce sometimes exquisite figure, errant grain becomes a blessing. In structural applications, such as home construction, lumber (mostly softwood) with other than straight grain loses some strength. And hardwood boards without straight grain require extra care in machining to avoid tear out and other reactions.

Grain means texture, too
Texture means the relative size as well as the amount of variation in size of the wood cells. It's the cells and how they're arranged in bands called rays, and the size and distribution of pores, that make the difference between fine-textured wood and coarse-textured wood. Woodworkers, though, say "fine-grained" and "coarse-grained" rather than use the word texture to describe this characteristic of wood. And you don't have to be a wood technologist to see as well as feel the difference in grain.
First let's go over the three grain types there are.

1. End Grain (usually not exposed after a project is finished due to it's nature of absorbing too much stain)
The end grain is the little straw ends of the natural fibers in the tree. These used to be feeding tubes. There are 2 end grains on each board.
2. Face Grain (Most commonly used to display a finished even toned pattern)
Face grain is what you normally see when you look at your cabinets, or the side of the wood you can easily identify tree species. This grain is often the most precious side of the board. A piece of wood normally has 2 faces.
3. Edge grain. (This is the strongest side of wood. Quality cutting boards are made from maple on edge.)
Edge grain is usually the same side you measure thickness from. It can be stained to match the face and looks similar to face grain. Edge grain is acceptable as face grain on certain applications.

As with the cat theory, the same applies for wood grain. If you look at the edge or face of a board you can easily see the pattern. We used red oak to express this, for it's natural prominent grain pattern.
turned on edge

As you can plainly see the grain lays in a distinct pattern. This is the direction it grew in and will always stay that way. This example has a tendency to go left to right. meaning a cutter should move right to left. If you tried to cut against the grain the wood will splinter and try to continue down the grain line. If cutting with the grain, the wood chips would clear out smoothly revealing a nice clean cut.
Some examples below.

This one the grain goes right to left meaning you cut left to right. An example of a face cut

This example demonstrates a left to right grain. And feed again is opposite that. This demonstrates jointing

Things to keep in mind:

When making an edge cut, you will be reading the face grain.

When cutting the face grain, you'll read the edge grain.

Sometimes you won't be able to control which way to cut. This often happens while doing a project that needs lots routing. Most times it's after assembly of certain pieces that you run a decorative edge and need to pay special attention to details. These are instances of running against the grain. Sometimes it's got to be done, and when this is the casea you need advanced techniques and experience. Some people believe running the piece slower over the blade helps. To some degree this is true, but most times it's not.
check out my advanced routing and techniques. Covering against the grain cuts.
Coming soon, as this will be my next article.
This is pine Easy to read.

When jointing near a knot or check in the board use caution. The grain will often change direction. This is very common and should be handled appropriately. You read the entire length of the board. Majority of the grain direction is heading one way. This is the way you'll cut, taking time when approaching the knot and exiting. You will hear a distinct noise of wood breaking and chipping out where the cutter makes contact. There are tricks a jointer can do to prevent chipout or at least minimize it. I'll cover that at a later point.
Frankie Talarico Jr.
Woodworking supplies

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