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Of the four types of stress, racking is the most destructive. A racking force bends the members of a joint like levers. A lever, as you know, will move a heavy object when you apply a relatively small force — the force is multiplied by the pivoting action of the lever. For this reason, a small amount of racking will pop a joint that might otherwise withstand large amounts of tension, compression, or shear.

1 -3 Four types of stress may tear a wood joint apart — tension, compression, shear, and racking. Of these, racking is the most destructive.

For most woodworking projects, however, you must do more than pick a joint or two. You must design an entire system of joints — this is what a structure is. To build a structure, you must determine not only the types of joints in it but also their size and location relative to each other. This isn't difficult; it just takes some thought. There are a few simple com-monsense methods for designing a strong, durable structure:

1 -3 Four types of stress may tear a wood joint apart — tension, compression, shear, and racking. Of these, racking is the most destructive.

1 -4 Even before a butt joint is glued or fastened, it will withstand compression, but any amount of tension, shear, or racking will pull it apart. A mortise-and-tenon joint, on the other hand, will resist compression, shear, and racking. Only tension can pull it apart before it's secured.

1 -4 Even before a butt joint is glued or fastened, it will withstand compression, but any amount of tension, shear, or racking will pull it apart. A mortise-and-tenon joint, on the other hand, will resist compression, shear, and racking. Only tension can pull it apart before it's secured.

Butt Joi nt Resists Compression ONiy

Mortise $ Tenon Resists Compression, Shear, i Racking

Butt Joi nt Resists Compression ONiy

Mortise $ Tenon Resists Compression, Shear, i Racking

Racking ComStucco Over Sip Panels

Racking Force

-Tension

Compression

Racking Force

Tension

Note: Length of arrow indicates amount of stress or force at any

I -5 The racking force applied to both of these mortise-and-tenon joints is equal. But on the large mortise and tenon (bottom), the load is distributed over a larger area and more mass. The stress at any one point in the joint is a good deal less than that on the smaller mortise and tenon (top).

1-7 Structural triangles don't all have to look like roof trusses. On a table, the upper part of the leg and the apron form a hidden triangle that keeps the structure rigid. On a board-and-batten door, the nails form triangles that keep the door square.

1-6 You don't have to use massive structural members or joints to support a large load. On this Shaker rocker, the load is distributed over many small, round mortise-and-tenon joints. The chair's frame and joinery appear very delicate, yet it has survived constant use for almost two centuries.

Leg-anp-Apron Construction

Board-and- Batten Construction

1-8 The adjoining members of both the butt joint (left) and the box joint (right) are precisely the same size. However, the fitted fingers of the box joint offer more gluing surface than the flat surfaces of the butt joint. Consequently, the box joint is much stronger.

1-8 The adjoining members of both the butt joint (left) and the box joint (right) are precisely the same size. However, the fitted fingers of the box joint offer more gluing surface than the flat surfaces of the butt joint. Consequently, the box joint is much stronger.

Composite Decking Diagram

I -9 Wood moves in three different planes — longitudinal, or parallel to the wood grain, radial, or perpendicular to the annual rings, and tangential, or tangent to the annual rings. Wood is fairly stable longitudinally — it will only shrink or swell .1 percent of its length when originally cut. However, its unstable radially and tangentially. Furthermore, the tangential movement in most woods is about twice the radial movement. Radial movement averages 4 percent (of the original cut dimension) and tangential movement averages 8 percent.

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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