Popular Woodworking 2005-11 № 151, страница 49
When using a brad awl, begin by penetrating the fibers with the screwdriver point initially placed across the grain as shown above, and then push and twist the awl as it penetrates the fi bers (right). man-designed tool. Though we no longer use the birdcage awl for its original task (more about that later) this tool has this main advantage: It will make large or small holes to receive large and small screws as needed. Another advantage is its convenient size, which makes it much handier than a conventional hand drill or even a screw gun because of its single-handed simplicity, weight and compact size. Now let's take a closer look at the three piercing awls described above and the scratch awl. The Birdcage Awl The square-point birdcage awl also is known as the square awl or a sprig bit. Any one of these names will do, but the two true names are birdcage awl and square awl. The term "birdcage" identifies and isolates the tool to its original application rather than its more common function in our modern woodworking era - creating simple holes. At one time, country woodworkers made all types and sizes of birdcages for catching, transport ing and keeping birds. The cages were made from wooden frames within which wood, bamboo cane or metal bars were fitted to contain the captive birds. Cages for all types of poultry as well as exotic and singing birds were common throughout the world, and so this tool found its greatest use for boring fine, medium and large holes in rails of wood to build bird enclosures and all types of cages. Simple six-sided boxes and ornate, multilevel palace cages came from the craftsman's hands to entertain and decorate peasant homes and royal households alike. In fact, birdcages predate metal screws by many hundreds of years. In reality the birdcage awl was the only awl capable of producing a round hole in wood by actually removing material from the hole by its reaming action. Other awls, such as the brad awl, may come close but the birdcage awl could produce round holes more efficiently than any other tool of its type and in locations that no other awl could. Round-point awl The birdcage awl will not do what the screwdriver-shaped brad awl will do because it's square along the whole length of the bit. So when you turn the birdcage awl in the woody fibers it automatically reams out the whole length of the tapered hole rather than the periodic bypassing action that you can do with the screwdriver-shaped brad awl. Of course if you simply push and waggle the birdcage awl as you would a round-point awl and refrain from the twist-and-turn action, the birdcage awl will leave all the wood fibers in place. The Round-point Awl The round-point awl is simply pushed into the wood to the necessary depth. The advantage of this awl is that, particularly in soft-fibered woods, the fibers are compressed rather than cut or reamed away. When the awl is removed, the compressed fibers spring back so that when you screw into the parted fibers of the hole with a wood screw, you have retained all the original fibers of the wood to then surround the threads of the screw. Also, because of the elasticity of the compressed wood fibers pressing against the wall of the screw's main body, you add even more security to the screw. The downside of the round-point awl is its tendency to split the wood rather than cut the fibers. It's a handy but sometimes restrictive tool. The Brad Awl Again, the name "brad awl" is a generic term meant for a pointed tool used primarily for piercing and separating wood fibers to receive screws and small nails. Woodworkers are typically called on to work with other materials such as cloth or leather. So for many years this tool also has been employed as a support tool for furniture makers undertaking upholstery or boat builders working with sail cloth and other canvas awning fabrics. Most woodworkers use the screwdriver-shaped brad awl until they discover the birdcage awl or the round-point awl. Discovering these other two awls, how to use them, sharpen them and how they effectively work the wood fibers, will exponentially change your perspective of awls. Both the brad awl and the birdcage awl will achieve similar results as each other. You can use them to simply separate fibers, or you can use them to ream out the fibers and bore clean, clear and round holes with a simple twist of the wrist back and forth. Although the screwdriver-shaped brad awl can be used both with or across the grain, we generally enter the wood cross-grain so that the leading edge of the awl performs similar to a dull chisel, severing the cross-grain fibers rather than simply parting the wood fibers to create a pointed hole. By repeatedly pressing and turning the awl alternately back and forth to deepen the hole, the awl parts the fibers and then ream s the next section of fibers below. This action of successive twisting and pushing retains more of the fibers on either side of the spade bit. As the point first forces and compresses the fibers apart, and then rips the fibers below, we effectively create a "compression, rip, compression, rip" effect popularwoodworking.com 47 |
