Within the world of drill bits, there are tons of different variants depending on your application. To get the best performance out of your drill bits, you should purchase the right ones for your needs.
What is the difference between a wood drill bit and a metal drill bit?
The main difference between a metal and wood drill bit is in geometry. The wood bit has a spur in the center that will penetrate the wood and keep the bit stable during drilling. The metal bit is a twist bit with conical cutting tips followed by spiral flutes.
The above image shows two of the most popular bits used for drilling wood and metal. However, drill bits come in a variety of shapes and sizes. Below we’ve made a comprehensive guide on both wood and metal drill bits to ensure you have the proper drill for your job.
Wood Drill Bits
A drill bit can be defined as a rotating cutting tool that is used to create holes in a piece of wood, plastic, metal, etc. Generally, a wood drill bit can be identified by the protruding point in the center and lips on the periphery. The center spur keeps the bit from wandering while the lips on the periphery act like a chisel to cut through the wood.
The concept of drills has been around since Roman Times. But as the revolutionary electric drill arrived on the market in 1889, wooden drill bits have been the most recognizable tool in this industry.
Over the years, multiple variations of wood drill bits were invented to enhance their capabilities. Although the abundance of wood drill bits can seem baffling, it’s exceptionally easy to familiarise yourself with them.
Types of Wood Drill Bits
Wood drill bits come in a variety of sizes and shapes to drill holes in different types of wood.
1. Brad Point Bits
This type of wood drill bit is by far the most precise and well-known in its category. Also known as lip and spur bit, it comes equipped with a small spur on the drill bit tip. The Brad point bit is known as a dowelling bit since it is widely used for drilling holes to make dowel joints.
This allows users to place a brad point bit firmly into a wooden surface before drilling to ensure it stays in line. By offering this, people with this type of drill bit can have peace of mind knowing they’re not going to slip. The brad point bit works well with handheld cordless drills as well as on drill press.
- What does it drill? – Composite wood, Softwood and HardWood
- Ideal Application – To drill small accurate holes into wood.
- Used for – Furniture making, doweling, and various other applications that require small drills around 1/8 inch (3mm) – 1/2 -inch (12mm).
2. Spade Bits or Paddle Bits
These next drill bits are perfect for drilling large diameter bores. However, they’re commonly known to be a “rough” cut when drilling. This is because of the spade bit’s wide-cutter design.
To avoid the wood from becoming rough or splintered, many professionals drill from both sides. You can also buy extensions for spade bits to increase their overall length to suit your application.
- Suitable for – Drilling wood
- Ideal Application – To bore large diameters.
- Used for – Any job that requires a large bore. Typically used while framing or within the plumbing and electric industry – drill bits range from around 1/4″ (6mm) – 1 1/2″ (38mm).
3. Auger Bits
These bits have close spiral body with low helix angle. It has screw tip in the center that will penetrate and pull the wood towards the bit.
Many woodworkers use auger bits in conjunction with hand drills. This is because it allows the auger to perform better, as it’s able to extract the wood easier without clogging up. But as new and improved auger bits were released into the market, many people use these with a power drill due to convenience.
- Ideal Application: To drill deep holes in wood.
- Used for – Framing and any other task that requires a long or wide drilled hole – sizes 12″ long (can get smaller, and extensions to increase the length) 1/2″ (12mm) – 1-1/16″ (26mm).
4. Installer Bit
Ever wondered how an electrician gets their wires through a large wooden beam? Well, they’ll probably be using an installer bit. With this drill bit, you can make thin, long holes through wooden beams to allow cables to be pulled through.
- Ideal Application – For drilling holes to pull wire or cable through.
- Used for – CCTV, telephone, or anything that needs to be wired around a property – sizes range between 1/4 inch (6mm) – 3/8 inch (10mm).
5. Forstner Bits
The Forstner bit is widely known in the woodworking industry as it provides accurate flat-bottomed holes. It was patented by an enthusiastic woodworker by the name of Benjamin Forstner back in 1874.
Since its release, there haven’t been only minor changes on this bit due to its excellent structural design. It comes with two large gullets that extract wooden chips quickly and a center spur point for enhanced drill accuracy.
- What does it drill? – Softwood, hardwood, plywood
- Ideal Application – To bore flat-bottomed holes (can also bore off-center and angled)
- Used for – Most applications that require a sizeable accurate bore – they typically range between 1/4″ (6mm) – 2-1/8″ (54mm).
6. Hole Saw
A hole saw or hole cutter is a complete circular cutter that is used to create clean holes in many materials. Typically, hole saws are used for wood applications, but you can get them to cut through thin layers of aluminum and stainless steel.
- What does it cut? – Primarily wood (You can also get hole saws that cut thin sheets of aluminum and stainless steel).
- Ideal Application – For drilling large clean holes through wood.
- Used for – Typically for pipe fitting or tasks that require large holes, – size ranges between 3/4″ (19mm) – 6″ (152mm).
You can also get diamond core bits, which are design to drill masonry without hammer drill.
- Related info: Masonry versus wood drill bits
Now you’ve gathered a general understanding of what wooden drill bits are available in the market. It’s time to learn about metal bits.
Metal Drill Bits
Twist drill bits are the most common type of bit for drilling holes in metal. The metal drill bits commonly get confused between wooden ones. Although metal drill bits can be used for wood, they do not have protruding lips and are hence less efficient at creating holes with a good finish in wood.
To find out what metal drill bits are suitable for, see below:
Twist Drills
A twist drill bit is a cutting tool that has a conical cutting tip and spiral flutes that form a twist on the drill’s axis. The point angle of a general-purpose metal drill bit is 118° while bits designed for drilling harder material may be ground to an angle up to 135°.
The helical flutes carry the curled metal chips out of the hole from the cutting area.
The most common type of metal drill bit is the HSS twist drill. These can be found in almost all the hardware and tools shops.
The standard length bit is known as the jobber bit although you can get them in different lengths.
Twist bits are made in a variety of materials, such as high carbon steel, high-speed steel (HSS), Cobalt, and carbide. Each material has its own advantages and disadvantages, but it’s known that carbide is one of the more robust types of twist drills.
The bright finish HSS bits are the cheapest and are suitable for cutting wood, plastic and soft metals. Next is the black-oxide coated bit that offers better tool life and is good for mild steel, aluminum, copper, brass, etc. A titanium drill bit with a more expensive titanium nitride coating is excellent for most steel, including cast iron and stainless steel. You need a cobalt drill bit or tungsten carbide bit to drill hard metal and tough alloy tool steels such as Inconel.
If you want o drill a hole in hardened steel, you need a carbide bit or a masonry drill bit with a tungsten carbide tip.
When compared to titanium bits, cobalt bit and carbide bit allow you to sharpen several times and maintain the cutting edge quality. You can also sharpen the masonry bit until the carbide tip lasts.
- What does it drill? – Mainly metal (you can also drill various other materials with a twist drill, such as plastic and wood.
- Ideal Application – For small and precise holes that need to be cleaned through.
- Used for – General purpose, ideal to have in your toolbox as they can be used for most domestic jobs.
Step Drills
On the list so far, this might be the most peculiar. A step drill bit has many names, including a cone drill, Unibit, multi drill, and I’ve even heard someone say Christmas tree drill. They all mean the same thing, and this type of drill is typically used as a pilot bit or for drilling holes in thin sheets. This includes pilot holes before more significant drilling or pilots before creating or repairing a thread.
- What does it drill? – Primarily metal (can be used on wood).
- Ideal Application – Useful for drilling sheet metal, thin plastic, fiberglass, etc.
- Used for – Mainly by handymen and construction engineers for convenience with jobs that require thread repair.
You can use step drill for a wide variety of applications and is an excellent tool bit with one caveat; it can’t drill holes deeper than the step height.
Center Bits
Lastly is a center drill (drill & countersinks), and these are used for spot drilling on drill press, lathe, and milling machines. These are great because they have thick and sturdy shanks that don’t flex. This is essential for high-speed drilling, as it makes them incredibly accurate and hard to break.
- What does it drill? – Metal
- Ideal Application – Normally equipped onto a drilling press or lathe.
- Used for – Creating accurate pilot holes on a lathe or drill press.
As you’re able to grasp from the above, there are plenty of different drill bits to select from depending on your application. If you want to make your job easier and more precise, it’s recommended to use the ideal drill bit for that job.
How to Identify a Wood Bit From a Metal Drill Bit?
Although most drill types are pretty identifiable, the two that get mixed up are both brad-point (wood) and twist drills (metal). At first sight, as a novice, they can look somewhat similar. But failing to use them for the proper purpose can be catastrophic and result in you burning them out or splitting the wood. Here’s how I would identify each of them:
Appearance
First, you’ll want to evaluate the appearance. Typically, all brad point drills will have a pointed spur located on the tip of the drill. Although some high-quality carbide twist drills are ground to have a self-centering tip like this, they won’t be pointed and protruding out. Normally they’ll have a small pilot drill area ground at the web that looks similar to a center bit on the tip of the drill.
Something else to look out for is markings that are on the shank. Although these wear away very fast after use, if they’re relatively new, you should be able to see abbreviated “code” to identify them. For example, it may have the drill size, then HSS (metal – high-speed steel), HHSCO (metal – high-speed steel cobalt), TIN (metal – titanium), or W (Wood – normally HHS or similar material).
Design
If you’re unable to identify what type of drill it is through its appearance, you should then look at the design. With paddle bits, the cutter is wider. Other bits such as Frostner bit and hole saw also have unique designs that you can identify easily.
Drill test
Lastly, if you’re really struggling to recognize your drill bit, you should perform a small drill test. While bits can cut through wood, the resulting surface finish will be different. This allows you to see which one has a smoother drilling process. Typically, if it drills through the wood with ease and doesn’t feel restricted, it’s a brad point bit.
Can I Use Metal Drill Bit on Wood?
You can use a metal drill bit to drill wood. However, it will be difficult to locate large-diameter twist drills without the spur tip and may experience walking. They will also cause splintering and will result in a poor finish. You may also find tear-outs at the bottom of the hole.
Conversely, you cannot use a wood bit on metal since the cutting tip will immediately get damaged. You could drill a few holes in soft metals like aluminum with a drill bit if the material thickness is less. However, the bit will get burned out fast.
Final Thoughts
After reading the above, you should know and be able to identify the different types of drill bits that are available in the industry. Knowing this is helpful to ensure you have the right tools for the job. Now, what should you do? If you need to, increase your arsenal of drill bits to guarantee you have something suitable for your upcoming projects. Lastly, happy drilling!
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