Drill bits come in a huge variety of shapes and sizes, and finding the right bit for the right job can seem daunting. However, standard drill bits are generally designed for wood, metal, or masonry, and one can familiarize oneself with different bit types before buying drill bits from a hardware store or an online source like eBay. Additionally, bits designed for metal can usually be used on softer materials like wood or plastic. One should never reverse this and use a bit intended for a softer material (like wood) on a harder material (like metal or masonry) as this could damage or break the drill bit.
Drill bits are available with a range of coatings and can be made from a number of different materials. One should choose a bit with the appropriate hardness and added durability features needed. Finally, one should learn how to properly take care of bits to get the most out of them.
Drill Bits Used for Wood
There are three main types of wood drill bits, namely brad point bits, auger bits, and paddle bits. Additionally, there are specialty bits appropriate for specific woodworking tasks.
Brad Point Bits
Brad point bits are also known as dowel or W-point bits. They can be recognized by the small point at the end of the bit. The bit features spurs on either side of the point that are designed to cut clean, straight holes in all types of wood. Because the edges cut through the wood before the center breaks through, the bit does not grab. These bits sometimes come with depth stops, or small rubber rings that fit around the bit to allow the user to choose the depth he or she would like to drill. Dowel bits come in a huge variety of lengths and sizes.
Auger bits are used to make large, deep, accurate holes in dry timber. They feature spiraling shafts that come to thin, threaded points.
Paddle bits are also called wood spade bits. These bits have a pointed tip that starts the hole. The spade-shaped blade follows to drill a large, wide hole. With spade bits, the bit's size is usually indicated on the paddle's face. Sizes range from 6 to 38 millimeters in diameter.
Specialty Woodworking Bits
Some bits are less common and considered specialty woodworking bits.
- Countersink bits are used to drill a hole and cut a space for the screw head. Using these bits is a great way to prevent wood from splitting. Drill/countersink bits combine the drill bit and countersink bit to offer an all in one solution for drilling holes for countersunk-head screws. One can also find countersink bits for metal.
- A plug cutter is used to cut wooden plugs that cover screw heads. The plug is removed through a side opening in the bit.
- A hinge cutter is used to cut holes for cabinet door hinges, and usually features a tungsten-carbide tip.
Drill Bits Used for Metal
Metal bits are also known as high-speed steel (HSS) or twist bits. They are usually black in color and can be used for wood and plastic. While HSS bits can be used for drilling plastic and wood, one should never use wood bits to drill metal. Most metal bits come with cylindrical shanks, but some feature quarter inch hex shanks. The latter allows one to use the bit with tools like impact drivers or cordless screwdrivers for minor drilling tasks.
Reduced Shank HSS Bits
Reduced shank HSS bits allow one to drill a hole that is larger than the drill's chuck would normally allow. If one decides to use a pilot drill before making the hole, one should not use a bit with a diameter that is greater than 25 percent of the reduced shank bit's diameter.
HSS Rivet Bits
Rivet bits are specifically designed for drilling holes for rivets. They often have flutes on both ends. Rivet bits are made to drill shallow holes through thin metal. The hole must be larger than the rivet to reduce metal fatigue and allow for the rivet's expansion.
Masonry Drill Bits
Masonry drill bits are designed to drill into a variety of masonry surfaces. These bits often have tips that are made of extra-hardened material. Because a variety of materials are used when making these bits, colors may vary. Where bits have a hardened coating the color may vary between the shaft and the tip. Certain professional quality bits have a hexagonal shank (rather than a cylindrical one) to stop the bit from slipping in the chuck. Masonry bits tend to heat up quickly when used and this can chip or otherwise damage the tip. One should withdraw the bit often in order to clean the flutes, and one should use the correct drilling speed.
Rotary bits have carbide tips for added strength and durability. They can be used to drill into stone, brick, concrete, and cement without losing a great deal of sharpness and without being damaged.
Percussion bits are designed for use with drills with hammering functions. Using the hammer function allows one to penetrate masonry more easily.
Diamond bits are used for hard-surfaced masonry. They can also be used on porcelain. One must start drilling at a 45 degree angle to stop the drill bit from slipping. The drill can be straightened slowly during drilling. For proper performance the bit needs to be supplied with water constantly and it must be used at a very slow speed.
Multi - purpose bits can be used in both rotary and hammer drill modes as they feature special diamond ground tungsten-carbide tips. They can be used to drill through nearly anything, including plastic, wood, ceramic tiles, masonry, and metal.
Special Drill Bits
In addition to masonry, metal, and wood bits, there is a wide range of specialty bits available that are made for a specific task or to fit a particular type of chuck mechanism, and they likely will not work with any other type.
- Glass and tile bits have tungsten-carbide tips that are spear shaped. These can penetrate a tile or a piece of glass before enlarging the hole to the diameter of the tip's base.
- A hole - cutter bit, or hole saw, is used for cutting wood and metal. A drill bit in the middle cuts first, and the cutter makes a larger hole afterwards.
- Screwdriver bits are available for flat, Phillips, pozidriv, and square drive (like those found on deck screws) screw heads. Some designs allow them to be placed directly into the chuck, while others require them to be put into a bit holder that is inserted into the chuck.
- Special drilling system (SDS) bits are used in rotary hammer drills for drilling holes into dense masonry.
- Step bits have a staircase profile that runs from a narrow point to a wider base in a nearly conical shape. These are used for making holes in soft materials or for enlarging existing holes. They can also be used for deburring. A similar bit without the steps is called a conical bit.
- Saw bits have HSS drill bit points, but feature shafts with abrasive patterns. Applying lateral force to the bit enables it to saw holes into wood or metal.
This list is not exhaustive and one may find additional specialist drill bits.
Drill Bit Sets
Those who do a lot of drilling may prefer to invest in a drill bit set. One should always use the bit that is designed for a particular job as this will increase the lifespan of one's bits. Some sets contain only one type of bit (for example masonry bits), and some sets contain a variety of commonly used bits (like the common sizes needed for wood, metal, and masonry).
Materials Used for Drill Bits
Carbon-steel bits are strong and durable and can be resharpened. This is a popular material for auger bits. Some masonry bits come with chrome-vanadium shafts and tungsten-carbide tips to improve durability. Black oxide HSS bits last twice as long as conventional bits. Higher-end metal bits often come with a titanium nitride coating that extends the bits' cutting life, with these bits lasting four to six times longer than their conventional counterparts. This coating reduces heat build-up and increases the bit's lubricity. Zirconium coatings give bits a harder finish that decreases friction and extends the bits' lifespan. Cobalt metal bits are very resistant to abrasion and high temperatures. They are used when drilling into materials like aluminum, cast iron, bronze, and cast steel.
Getting the Most Out of Your Drill Bits
Following the tips below will increase the lifespan of one's drill bits and improve their performance.
- When drilling hard materials, use a slow drilling speed. Conversely, soft materials require a faster speed.
- Applying cutting fluid to a bit when drilling metals (except iron and brass) will yield better results.
- Let the bit cool naturally. Do not immerse it in water to speed the cooling process.
- Lift the drill bit often as this clears the flute and allows air to reach the bit, cooling it.
- Creating center punch holes will mean drilling is more accurate.
In addition, one should always wear the appropriate protective clothing when operating power tools.
Buying Drill Bits on eBay
Drill bits are listed in eBay's Home & Garden section, in the Tools department, under Power Tools. Use the search function to find exactly what you need. Type a keyword or search phrase in the search box and use the advanced search function to narrow or expand your search results. Be sure to check eBay Stores for more great deals.
Know Your Seller
Before you make a purchase or bid on an item on eBay, take a moment to meet the seller. The eBay seller feedback system makes this easy. You can see what other buyers have thought about a seller's products or services through the seller's feedback rating. Don't forget to take the type of items sold and the number of sales completed into account when viewing this information.
Further, read the seller's terms and conditions of sale. Some sellers offer a money back guarantee or free shipping, and many sellers have returns policies like regular retailers. Make sure you read the terms and conditions of the seller's return policy to ensure that you can return items if necessary. If the seller does not offer free shipping, add the shipping fees to the item's price to work out its total cost. If you are unclear about anything about a listing, contact the seller by clicking on the "Ask a Question" link.
Finding the right drill bit can seem overwhelming, especially for those who are not familiar with the plethora of different bits available. Standard bits are generally made for wood, metal, or masonry. As long as one remembers that a harder bit can generally be used on a softer material (but not vice versa), finding the right drill bit becomes a great deal easier. Specialist bits are used for specific applications and one will usually become aware of needing one of these when researching a particular task. eBay sellers offer drill bits for individual sale or in sets. Sets can have either a range of sizes of a specific type of bit, or a range of common sizes for several different materials and uses.