Navigating the realm of drills and bits can be a daunting task, especially for those new to the world of woodworking and metalworking. In this comprehensive guide, we delve into the intricate details of these essential tools, shedding light on their diverse applications and the terminology that surrounds them. While the traditional distinction between "boring" in wood and "drilling" in metal may still hold, modern discussions often blur these lines. Regardless of the semantics, one thing remains constant: the bits themselves differ significantly when working with wood or metal. From machine spur bits and spade bits to rotary hole saws and fly-cutter-type circle makers, each tool serves a unique purpose. Join us on this journey as we explore the world of bits and drills, offering insights into their usage, proper maintenance, and material considerations, ensuring that you're equipped with the knowledge needed to tackle your projects with precision and confidence.
Types of Wood Bits
For woodworking tasks with a drill press, various wood bits come into play:
1. Machine Spur Bit: This bit, featuring a brad and lip point, is renowned for its efficiency in creating clean dowel holes. The spiral of a machine spur bit incorporates an opening known as the "throat" or "flute," with both terms being interchangeable. These bits are available in standard sizes from 1/4 to 1 inch, with fractional increments of thirty-seconds of an inch.
2. Spade or Speed Bit: For drilling larger holes in wood, spade bits or speed-type bits are ideal. These flat bits boast a brad point and range from approximately 3/8 to 1-1/2 inches. They excel in chip removal and tend to minimize binding. To prevent surface splintering when drilling, initiate the hole slowly, ensuring the bit goes in perpendicular to the wood. Additionally, you can avoid back surface splintering by either stopping the drilling as soon as the pilot bit emerges or by placing a scrap piece behind or beneath the workpiece.
3. Rotary Hole Saw: When tackling holes larger than 1-1/2 inches, a rotary hole saw, resembling a circular saw blade, offers precise cutting in materials like metal, plastic, and composition board. These hole saws come in various sizes, from 3/4 to 2-1/2 inches in diameter, some equipped with fine-tooth blades for smooth yet slower cuts and others with multiple teeth for quick but rough cuts. It's crucial to choose a hole saw of an appropriate cutting depth, matching your material's thickness.
4. Fly-Cutter-Type Circle Maker: To create holes ranging from 1/2 to 8 inches in diameter, consider using fly-cutter-type circle makers. Adjust the hole size by sliding the cutter blade in or out. For cleaner results when cutting circles in wood, make halfway cuts from both sides or support the wood to avoid tearing or splintering as the blade passes through. Position the cutter blade about 1/2 inch behind the center drill bit to ensure a secure grip during cutting, as fly-cutters work best at lower speeds.
Preventing Splintering: To prevent splintering on the far side of the workpiece, drill halfway through and finish the cut from the opposite side, utilizing the pilot hole for accurate alignment.
It's important to note that a wide range of bits is available for various tasks. However, exercise caution and never use a self-feed bit on your drill press, as it can lead to dangerous situations.
While twist drills are primarily designed for metalwork, they can be employed for drilling holes in wood, plastic, ceramic, and other materials. Recognized for their efficiency, these drills have a sharp cutting edge responsible for removing material during drilling. Maintaining a point angle of 118 degrees is suitable for general work, though a sharper angle is recommended for extensive wood drilling.
Checking the Point Angle: You can easily verify the 118-degree point angle with a drill-point gauge, ensuring both lips are of equal length for precise drilling. While twist drills can withstand significant wear and tear, proper sharpening prolongs their lifespan.
Understanding the Shank: The shank, the part of the drill that fits into the drill press's spindle or chuck, is typically straight for drill press use. Taper-shank drills can also be mounted using a taper-shank spindle.
Material Matters: Twist drills come in two primary materials: carbon steel and high-speed steel. High-speed steel drills, featuring alloys like tungsten, chromium, and vanadium, excel in metalwork and can handle high heat without dulling. They often don't require coolant during operation. In contrast, carbon-steel drills are softer, best suited for wood, soft metals, or plastics, but wear quickly if overworked, necessitating coolant when drilling soft metals. Additionally, carbide-tipped drills are available for masonry, ceramics, and exceptionally hard materials.
In conclusion, the world of drilling and boring offers a diverse array of bits and drills tailored to specific materials and tasks. Whether you're working with wood, metal, or other materials, selecting the right tools and techniques is crucial for achieving precision and efficiency in your projects.
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