How to Choose the Right Wood Drill Bit
How to Choose the Right Wood Drill BitSelecting the right wood drill bit for your application is important; something as simple as boring with the right drill bit can expand your reputation for craftsmanship and producing a quality product.
Choosing the right wood drill bit is influenced by the type of wood you’ll be boring, its size, and its hardness plus making the best match for every hole’s diameter and depth, combined with the volume of work, and the tools you’ll be using. All these factors help you choose the right bit as well as extend its life span and the life span of your drill. This will save you money on materials and labor costs while completing your project on schedule.
But let’s not forget the most important consideration of using the right wood drill bit; safety for you and your crew. Boring holes in dry timber, thick joists, or large beams can be dangerous enough without worrying about flying broken bits, drills spinning out of control, or splintering wood. The right wood drill bit helps to eliminate these dangers.
Let’s take a look at wood drill bit designs, their benefits, and a couple of quick guides to help you easily and quickly select the right bit for each job. If you need help selecting any kind of bit that White Cap stocks, from our large in-stock selection of wood, metal, masonry, and concrete drill bits, visit your favorite White Cap location, or call us at 1-800-944-8322.
Heads Up on Wood Drill BitsThere are so many differences between concrete, masonry, metal, and wood drill bits that sometimes choosing the right bit can be confusing. For this article, we'll focus on bits used in power drills in construction applications, and leave out those for use in hand braces, CNC machines, and such.
Wood Drill Bit Anatomy
Compared to concrete and metal, wood is a sensitive, organic, and unique material of varying degrees of hardness. Wood needs special drill bits designed to drill holes without splitting or splintering and also quickly move the wood material out of the hole to prevent your drill and bits from overheating.
Like most drill bits, wood bits have three main components:
- Head or tip of the bit responsible for cutting or boring into wood. Many have spur tips that "pull" the bit through the wood.
- The Flute is the recessed spiral groove that removes dust and shavings during drilling. The deeper the groove, the faster chips are removed, preventing tool jams and overheating.
- Shank is the end that fits into a drill’s chuck to hold the bit in place during drilling. Wood drill bit shanks can be round, flat, or hex-shaped when the strongest grip is needed for drilling large holes. 1/4", 3/8" or 7/16" hex quick-change shanks are available on some bits. These are primarily used with impact tools for applications where reactionary torque presents a challenge, such as standing on a ladder, or a utility pole.
- Length and diameter are measured the same on all bits. You always need to know the depth and width of the hole you want to drill before you can choose the right bit.
TIP: Go short. Any time you can use a short bit instead of a long bit, do it. Short bits are more accurate, more rigid which means less breaking, better in tight areas, and save money while increasing productivity because your crew isn’t distracted by changing bits frequently, less money spent buying replacement bits, and your project is that much closer to being on schedule.
Types of Wood Drill Bits
- Here are some commonly used bits that should be in every toolbox. If you need help selecting the right bit for your job, visit your nearest White Cap store, or call 1-800-944-8322, and speak to one of our knowledgeable and experienced construction pros.
Bits for Rough Applications
Spade bit (also Paddle bit)
- - General purpose bit that bores large rough holes in all types of wood. This bit has a small ¼” hex shank for a strong chuck grip and has a flat, long spike with a centering point, or auger point, with two spurs on each side.
- - Available in diameters from 1/2" to 1-1/2" for drilling deep holes in dry, thick, hard lumber with minimal effort. Can bore through wood up to three studs, thick beams, and flooring joists. Long, deep spiral flute looks like a corkscrew and removes chips effectively. The auger has a hex shank for a strong grip and a screw-thread tip. Ship Augers have tough cutting edges for resistance to nails or screws, while Spur Augers have an additional spur that scribes the outside of the hole for a cleaner cut. You’ll need a powerful drill and strong arm to handle this bit – or use with an impact tool to reduce reactionary torque.
Saw-tooth bit - Self-feed bit
- - Made for cutting large-diameter holes from 3/4" to 4-5/8" with extreme durability in tough materials including nail-embedded wood. Replaceable auger points pull the bit through the wood and bits can have 1-3 cutting edges and saw-tooth cutters around the diameter of the bit. Some bits have replaceable cutters for longer life.
- – This unique bit is available in diameters from 3/4" to 6-3/8" in a variety of materials. Hole saws can come with bi-metal or carbide-tooth construction for longer life. A short open cylinder bit with saw teeth on an open edge, this unique-looking bit cuts large holes in thin material. Material is cut away from hole edges only, leaving an intact disc, unlike all other bits which remove all interior material. Side slots help to eject the plugs. Hole saws have replaceable centering drill bits and arbors that fit different size bits, so check carefully to make sure you get the right arbor. Specialty arbors can include quick-change attachment, and some can support holding two saws (one nested inside the other), for enlarging holes. Hole saws cannot generally cut overlapping holes.
Bits for Smooth and Specialty Applications
Brad Point bit (also Spur or Dowelling) – A variation of a twist bit, but the tip is shaped like a “W” with sharp spurs on both sides of a center point. Sharp outer spurs start cutting before the center point makes surface contact creating less resistance, no surface splintering, and a cleaner hole. Use a brad point to cut small, straight clean holes in all wood types for screws and dowels.
Countersink bit (also Screw Pilot) – A specialty bit that can drill a pilot, countersink, and counter bore holes by cutting funnel-shaped recess for screw head so the screw fits flush to the wood’s surface. You can buy combo drill/countersink bit set that drills the screw hole and the screw head recess, or buy countersink bit separately. This bit will “chatter” and leave a rough surface when used with a power drill to countersink an existing hole. For best results, use before hole is drilled; then make sure countersink is centered.
Installer (or Bellhanger) bit – A specialized twist bit designed for installing wiring for entertainment or security alarm systems. The Installer bit is available in lengths from 12" to 30" and some have quick connect shanks that can use extensions. It drills through wood, some masonry, and plaster. Drill through the desired surface, insert a wire into the small bit hole, and use the bit to pull the wire through the hole, then attach wire to other wires or cable. Use also to create plugs to hide countersunk fasteners.
Pilot Point bit – This is a center point bit with two spurs. Pilot point bits resemble spur point bits, but they can be used in metal, wood, and plastics. Unlike normal twist drill bits, the twisted flute bits are ground away, making a truer, more accurate bit than normal twist bits. They cut a clean hole and cause little damage when they break through the back of the workpiece.
Long Boy bits – are typically used when drilling bolt holes in beams and hardware such as post and beam anchors. They are similar to twist bits but with diameters up to 1-1/4" and 12" long. They drill clean, straighter holes than augers.
Fish bit (flexible drill bit) – No, not for catching fish, but for drilling holes to fish wires through. These specialty bits are long (up to 6') with flexible shafts. Some systems offer interchangeable heads for drilling through different materials, like auger heads for clean wood, or others for masonry. Some can also connect to extensions for longer drilling needs.
Two Tips for Drilling Clean Holes
Drill bits are categorized by the materials they are constructed from and by their different coatings. Both categories determine a bit’s strength, life span, resistance to abrasions, corrosion, heat, and durability.
Wood Drill Bit Materials and Coatings
Built to Last
High-speed Steel (HSS) - A special type of carbon steel that is good for drilling wood, fiberglass, PVC, and soft metals. Developed to withstand high temperatures created during high-speed drilling, maintains structural integrity and hardness, and adapts to coatings. HSS and Black Oxide are typically sufficient for wood drilling. Coatings like Titanium Oxide, or materials like Cobalt are more appropriate for metal drilling.
Carbon Steel (low & high carbon) - Low carbon steel cuts wood, is inexpensive, and can be sharpened to extend life span. High carbon steel rarely needs sharpening, has a long life span, cuts wood and metals, and is better at cutting hardwoods than low carbon steel.
Coatings are designed to enhance drill bits by adding strength, lubrication, durability, plus resistance to corrosion, heat, friction, and other factors. All while increasing the bit’s life span and saving you time and money while increasing the quality and quantity of your jobs.
Coating Selection Guide
Drill Bit MaintenanceIt’s important to keep your tools clean, sharp, and ready for the next job. Basic maintenance increases the life span of your drills and wood bits, helps both perform better, and makes your jobs run easier and cleaner, and even increases customer satisfaction.
- After each job, check your tools to see what needs to be cleaned, sharpened, repaired, or replaced.
- Just like all bits, wood drill bits need to be sharpened frequently. Dull bits leave rough cuts, take longer to perform, can increase labor costs, decrease productivity and profits, and may create safety hazards.
- Purchase a drill bit sharpener and do it yourself. A good quality sharpener is inexpensive, takes little time, and while saving you money, it also saves you the hassle of taking the bits somewhere to be sharpened.
- If you buy bits individually, invest in a storage case with individually sized slots labelled for each size. You’ll be able to quickly see what’s missing, needs cleaning, sharpening, or replacing. The cases are inexpensive and a great time-saving investment.
- Always cool bits before wiping down with a clean cloth.
- Clean, old toothbrushes are a great, inexpensive tool to brush off clingy shavings.
- Rub bits with a clean cloth dampened with a couple drops of machine oil. Let sit for a few minutes, then wipe off with another clean cloth. Don’t store oily or damp bits. Your storage case should always be dry to avoid creating rust on bits.
- Check all your tools at least once a year. Check the plugs and cords on your drills and extension cords. Even the toughest cords pull from the plugs or fray from frequent, heavy-duty use.