Drills are handy tools that benefit everyone from a DIYer to professional craftspeople. However, to ensure that you do not destroy the material you are attempting to drill into, it is imperative that you use the correct drill bit.
The following is a comprehensive list of the most common drill bits and their uses. Read on to find the most appropriate drill bit for your project.
What are Drill Bits Used For?
Drill bits are designed to drill holes in a variety of different common materials. These include different types of wood, metal, plastic, ceramic tile, porcelain and concrete. Drill bits made for steel, aluminum, copper, cast iron, sheet metal, fiberglass, brick, vinyl flooring and more are also available.
Sized for their diameter, drill bits are constructed in a range of styles to help with specific tasks. Not sure which drill bit you need or what you need in your toolbox? Keep reading for a rundown of the different types of drill bits you’re likely to come across.
Drill Bit Materials and Finishes
The materials from which bits are manufactured and the finishes applied to them play a significant role in the life and performance of the bit. Common materials and finishes include:
- High-speed steel (HSS) drill bits can drill wood, fiberglass, polyvinyl chloride (PVC) and soft metals such as aluminum.
- Cobalt drill bits are extremely hard and dissipate heat quickly. They’re mostly used for boring in aluminum and tough metals such as stainless steel.
- Black oxide-coated HSS drill bits have a finish designed to help resist corrosion and increase durability. They last longer than basic HSS bits and work well on a variety of materials including metal, hardwood, softwood, PVC and fiberglass.
- Titanium-coated HSS drill bits produce less friction. They’re tougher than basic HSS bits and stay sharp longer. They work for drilling wood, metal, fiberglass and PVC.
- Carbide-tipped drill bits stay sharp much longer than steel, HSS or titanium bits. They’re effective for drilling tile and masonry.
Types of Drill Bits: Top 10
1. Twist Drill Bit
A twist bit is the most common type of drill bit for home use. It works for general-purpose drilling in wood, plastic and light metal. Twist drill bits are the most common type of drill bit and are used for everyday drilling in all types of material. They are also the most confusing due to the sheer number of size, tip, and material specifications.
Also known as high-speed bits, they resemble corkscrews and are some of the most popular bits. They are typically used to drill small holes into wood and walls. Their unique design allows them to channel dust from the hole as they work.
2. Flat Drill
This type of drill is generally made by beating slender sticks of high carbon steel. Their cutting edge is ground and then hardened and tempered. It can be made easily in any shape or size. These are made in different sizes after forging them. These drills are very cheap.
It is not used for boring holes in iron. It is usually used for boring holes in carpentry work and soft metals. The cutting point is kept at a 90° angle. On those solid metals where other drills get broken, this drill can be used after properly hardening and temping.
3. Straight Fluted Drill
A straight fluted drill consists of grooves or flutes running parallel to the drill axis. A straight fluted drill can be thought of as a cutting tool with zero rakes. This type of drill is not available in standard practice as the chips do not automatically pop out of the hole.
They are essentially used in drilling brass, copper, or other softer materials. In drilling brass, the twist moves faster than the rate of the drill feed, and the drill digs into the metal. There is no such difficulty in using a straight fluted drill.
4. Spur point bit
You might find the spur point bit also being referred to as wood or dowel bit. They are designed to have a central point and an additional two raised spurs on the sides.
The aim of these two spurs is to keep the drill bit drilling straight. It is advisable to use a power drill when working with a spur point bit.
This is because it will leave a clean-sided hole. Other than drilling wood, the same can be used for drilling plastics.
As for sharpening, use a fine file to sharpen the spurs and the central point at the front of the bit. Make sure that the angle between the spurs and central point is 90 degrees.
5. Brad Point Drill Bit
The brad point drill bit, or spur point, has the same shape as the twist bit, but the tip is shaped like a “W.” That allows the outer points on the edge to start cutting the hole before the center point makes contact with the material. Sizes range from 3 mm to 10 mm.
It means you get less resistance and a cleaner hole. Brad point drill bits are ideal for drilling wood and plastic, as well as specific jobs like dowling. These drill bits often have a depth stop to allow you to choose the required depth of the hole you drill.
6. Countersink Drill
There is no better tool for setting screws into wood than a countersink drill. It is designed specifically for drilling pilot holes in wood. Don’t mix up countersink with counterbores; they are two different kits.
Countersink drills, they’re also called ‘screw pilot bit’. As the drill drills deeper, the holes narrow, allowing for a more convenient and secure screw installation.
7. Step Bit
You’ll barely find a metalworker who leaves home without a step-bit drill in his sack. However, this drill bit is specially made for thin metal.
To drill metal or bore a hole into it, we must take into account the metal’s resistance and the speed of the bit. We can’t expect a great result without the right combination.
One of the interesting facts about the product is that it comes with a stepped design. This means that we can use the same drill bit to make holes of a variety of sizes. Additionally, the special design allows us to deburr holes, keeping the holes waste-free. In fact, many of us have found that this is a suitable tool for drilling timbers as well.
8. Hole Saw
Hole saws are bits that allow you to drill large holes such as those for door hardware installation.
This bit works equally well on thin as well as thick metal. To create large holes and wire pass-throughs, professionals often stick with this option. It is designed with two parts- a mandrel and a blade. Typically on heavier metals, such as ceramic, a hole saw with a diameter of 4 inches works well. Even so, it is best suited to iron, steel, and aluminum.
In addition, you can use an attachment to center the hole and use a pilot bit to stabilize the blade. Small hole saws include a built-in shank rather than a pilot bit. Using a bi-metal hole saw, you can make holes in both wood and metal.
9. Forstner Bits
These are what you use when looking to bore smooth and clean holes into woods. This bit also comes with a pointed tip to allow for easy positioning of the bit.
If you want to make clean and smooth holes in wood, then this type of drill bit is right for you. This bit allows precision cut holes. It has a pointed tip that helps to keep the bit exactly where you need it.
10. Installer Drill Bit
An installer bit is a specialized twist bit designed for installing wiring like what’s used for entertainment or security systems. The bit can be up to 18 inches long and drills through wood, plaster and some masonry.
Once you drill through the wall, floor or other surface, you insert a wire into the small hole in the bit and use the bit to draw it back through the hole you bored. You can then attach this wire to additional wire or cable and pull it through the hole.
Other Bit Options
In addition to more common drill bits, there are other options and accessories:
Drill saw bits cut irregular holes and contours in wood and metal.
Pocket hole bits are included with pocket hole jigs. They allow you to drill angled holes that accept screws for making wood joints.
Scaling chisels work in rotary hammers or hammer drills for chiseling, scaling and chipping masonry.
Depth stops prevent drilling beyond a predetermined depth.
Driver bits and bit holders work on a drill/driver to install or remove fasteners.
Drill bit extensions give your drill a longer reach.
Screw or bolt extractors work with a reversible drill/driver to back out damaged fasteners.
Right-angle attachments let you drill and drive in areas where a drill won’t fit.
Drill/driver bit sets collect various sizes and styles of bits in a convenient case.
Operating Tips
There are a few pointers that, when followed, will preserve the life of any of the above drill bit types.
Hard materials require slow drilling speeds, and soft materials require faster drilling speeds. Also, speeds should generally be decreased as the hole becomes deeper. For accurate recommended drilling speeds for HSS drill bits see the formula below.
You can centre punch holes first for more accurate drilling.
For better drilling results, apply cutting fluid to the bit when drilling metals (with the exception of brass and iron).
If you intend to drill all the way through a piece of timber use a wooden backing board behind the work to avoid material break out.
Always let the drill bit cool naturally. Never force them to cool down in water (or any other liquid).
Large drill bits will transfer substantial reaction forces onto the drill, so be prepared to hang on!
All drill bits should be lifted frequently to clear material from their flutes, and also to increase air flow around the bit to help it cool.
Always ensure bits are sharp to ensure less load on the power tool and better cutting results.
Always apply pressure in a straight line with the drill bit. You should apply enough so as to keep the drill biting, but not so much that the tools motor stalls or the bit deflects.
To prevent breaking through the material, reduce the pressure you are applying and ease the bit through the last part of the hole.
Final Thoughts
With all the different kinds of drill bits on offer, it can be a little confusing. Titanium nitride coated drill bits are tough, but cobalt is tougher. Carbide drill bits are the strongest.
Remember to think about what you need it for when considering which one you should use. What material are you drilling, and does it require a drill bit with strength, super-strength, or cutting power like it came from another planet?
It boils down to this — choose your drill bit based on price, the task you are using it on, if you want a bit with longevity, and whether you’ll hand-sharpen it. Carbide-tipped and titanium nitride drill bits will lose their superpowers if you hand sharpen them.