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Saturday, February 16, 2008

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Choose the right lumber to start your projects.

It All Starts With the Wood




Have you ever felt confused when you are ready to start a woodworking project? You are not alone, but It is not as hard as it seems. Woodworking really can be easy and a whole lot of fun. Let's start with the most basic element... wood. Lowe's is happy to provide this information as a service to you


















Wood Basics

In the USA, there are over 1,000 species of trees. Of these, only about 100 are used for constructing and manufacturing wood products. From this group, it's best to pick the ones that are easiest to work with and most appealing to you.

There are basically two kinds of wood from which to choose— hardwoods and softwoods. In addition, there are certain characteristics that are common in all wood types. Here are some common terms and definitions you should know:

HARDWOODS

These are the trees that lose their leaves in the fall (deciduous). Among an abundant variety, only 200 are plentiful and pliable enough for woodworking. Much like our skin, hardwoods have microscopic pores on the surface. The size of these pores determines the grain pattern and texture. Because of this, hardwoods are classified by pore openings as either: Closed Grained (smaller pores) — Most popular examples: cherry and maple; Ring Porous (larger pores) — Most popular examples: oak, ash or poplar.

Wood

SOFTWOODS

Softwoods come from "evergreen" trees (coniferous). Only 25 percent of all softwoods are used in woodworking. All softwoods have a closed grain (small pores) that is not very noticeable in the finished product. The most popular softwoods are cedar, fir, pine and spruce.

DENSITY

Heavy woods like oak are identified by their weight and tight grain pattern, and resist wear, dents and scratches better than softwoods.

TEXTURE

This is the wood property that determines the condition of the surface and stability. It plays an important role in deciding how a wood can be finished.

DEFECTS

Defects in wood are natural and are appreciated by many woodworkers for the unique character they contribute.

COLOR

Color contributes to the personality of wood. For example, red cedar will give you a very different look and character than white pine.


GRAIN

Grain is the most well-known wood characteristic. Grain pertains to the wood-cell fibers' orientation. The project you are undertaking dictates the most suitable type of grain.

Wood

GRADES

Lumber grades are determined by the number, location and size of defects in the board, not its strength. The clearer the wood, the higher the grade.

STABILITY

This is the wood's ability not to shrink or expand before or after it has been worked.

DURABILITY

Durable woods better resist excess moisture and exposure to the earth, where there's a greater chance of decay. Remember, no wood will decay if it's kept dry.

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A Closer Look at Wood Grain


Wood grain.

Wood grain

Two boards of the same species can look very different. Each tree has its own grain pattern. This is the direction in which the wood cell fibers grow. These variances in grain direction can have a significant impact on your project.

The grain direction is important to consider when building either structural projects or decorative projects such as furniture or crafts. For instance, when working on a structural application, a straight-grained board is generally the strongest. In more decorative projects, grain with varying characteristics can add beauty and personality to the project.

There are six general types of grain:

Diagonal Grain

When a straight-grained log is not sawn along its vertical axis, diagonal grain is the result.
Spiral Grain

When trees grow twisted, spiral-grained logs and subsequent boards are produced. Fibers follow a spiral course with a twist that is either left- or right-handed.
Straight Grain

The board's fibers run approximately parallel with the vertical axis of the log from which it originated.
Wood Grain
Wavy Grain

This type of grain results when the direction of wood fibers has constantly changed.
Irregular Grain

Boards of this type have fibers at directions that are varying and irregular from the log's vertical axis (for example: fibers around knots).
Interlocked Grain

Boards with this grain result from trees whose fibers lined up in opposite directions in each growth year.

Grain pattern density determines strength. As you'd expect, a piece of lumber with a tight pattern is stronger than one with a loose grain pattern. And when building, a board's strength is maximized when other pieces run across the grain pattern — not parallel to it.

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Making the Grade

When you are choosing lumber, do you know what the stamp on the wood actually means? Fear not! We've deciphered those hieroglyphics for you. So the next time you go to the lumber yard, you'll sound like a pro.

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Grades of Hardwoods

Grading designation depends on the number of defects in a given length and width of hardwood boards. As with softwoods, a lower grade can be perfectly acceptable, depending on placement and usage. Hardwoods are graded by the National Hardwood Lumber Association. Here's a chart to help explain the grading system. Grades are listed from highest to lowest.

Grade Name Abbreviation Minimum Board Size % Usable Material On One Face
Firsts and Seconds FAS 6" x 8' 83
Select Sel 4" x 6' 83
#1 Common #1 Com 3" x 4' 66
#2 Common #2 Com 3" x 4' 50

There are grades below #2 Common, but they are typically not suitable for woodworking.

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Grades of Softwoods

Softwoods are divided into two categories: dimensional lumber, with a grade based on strength, and appearance boards, which are typically used for woodworking projects. Grading of softwoods is overseen by a number of different agencies, so you will be more likely to find some variations in terminology. Grades listed here are from highest to lowest.

Grade
What It Means
C Select
Almost completely clear of defects. Widely used for interior trim and cabinets.
D Select
Fine appearance, similar to C Select. May have dime-sized knots.
1 Common
Best material for high quality pine with a knotty look. Knots will be tight, meaning they won't fall out and are generally small.
2 Common
Tight knots, but larger than found in 1 Common. Often used for paneling and shelving. Very suitable for general woodworking projects.
3 Common
Knots larger than in 2 Common. Also used for paneling and shelving, but especially well-suited for fences, boxes, and crates.
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Common Lumber Defects

Bow
BOW: Warp on the face of a board from end to end.


Cup
CUP: Hollow across the face of a board.


CROOK:
Warp along the edge line, also known as crown.


KNOT or KNOTHOLE: A tight knot is usually not a problem. A loose or dead knot, surrounded by a dark ring, may fall out or may have already left a hole.


SPLIT: Crack going all the way through the piece of wood, commonly at the ends.


TWIST: Multiple bends in a board.
Check
CHECK: Crack along the wood's annual growth rings, not passing through the entire thickness of the wood.


SHAKE: Separation of grain between the growth rings, often extending along the board's face and sometimes below its surface.

WANE: Missing wood or untrimmed bark along the edge or corner of the piece.


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Lumber Grading Stamp
Grade stamp.

Typical grade stamp

While lumber of the same species and size is still at the mill, it is designated and separated by grade. It is then identified by a stamp and often inventoried by its grade and species. When selecting wood, be sure you look for its grading stamp because different lumberyards sometimes use different names for the same grade. (And remember, if you are having trouble figuring it all out, ask for help.) Grade designations depend on particular defects such as knots or wane. Keep your project final results in mind when selecting the grade of wood. Grade does not indicate consistency of color or grain patterns.

Manufacturer: Mill's number, name, or symbol. (ex. 12)

Certification mark: Symbol of agency providing quality-control supervision. (ex. WWP®)

Grade: Often abbreviated. 1 Common shown. (ex. 1COM)

Moisture content (MC:) Abbreviation for MC when board surfaced. MC 15 is 15 percent or less;
KD or S-DRY is 19 percent or less; S-GRN is green wood with more than 19 percent MC. (Ex. S-DRY)

Species mark: Symbol or abbreviation for types of tree. Example shown is Ponderosa pine. (Ex. PP)

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