Countersinking helps fasteners and flathead screws remain touching the piece you’re working on.
Using a countersink drill bit reduces the risk of wood splitting, stops tearout, helps screws stay in contact, and can help DIY projects look better by ensuring that the screw head is fully inserted.
You’ll learn how to use a countersink drill bit properly in this article, but we’ll also cover what these drill bits are, if one is really necessary, and the different types of countersink drill bits that you may encounter.
You’ll also find out how these types of bits can help you to create a pilot hole of your desired depth for all kinds of woodworking projects.
Keep reading to learn more about using countersink drill bits!
What Do Countersink Drill Bits Do?
Countersink drill bits are necessary for two reasons.
The first is to drill pilot holes into a surface. Pilot holes are little openings made in workpieces to hold fasteners, like screws. Making a pilot hole aids in preventing the wood from cracking or splitting as you screw the screw into the correct depth to lie flush.
The second reason is that countersink drill bits make a countersink or a ‘V’ on the surface of a workpiece.
This indent helps countersunk screw heads drive level into the material to make screws look perfect when drilled properly into a hole, where most screws may otherwise look a little off.
When Are Countersink Drill Bits Necessary?
Countersink drill bits can be useful for a few reasons.
Stops Tearout
Countersink bits create a V indent which lets screws be driven level with the wood’s surface.
If you attempt to drive a screw level without a countersink bit, you may damage the fibers in the wood. This makes the wood’s surface look messy, which can lead to amateur-looking projects.
Another factor is the wood’s hardness. Even though it would lead to a tearout, driving a screw level without a countersink bit may be possible on softwood. However, drilling a hole in hardwood, such as cedar or oak, would be harder.
Lowers Risk Of Splitting
Driving screws results in an external force on wood, which can lead to splitting when not using the right tools or the right size bit with a screwdriver.
Creating pilot holes makes an area for screws, which lowers the external pressure. As a result, screws can be driven in easier, which lowers the risk of wood splitting when you drill a hole deep.
Improved Contact
Countersink drill bits make spaces in workpieces that align with countersunk screw heads. This form lets the screws stay touching the wood with equal pressure. This leads to a strong connection between the wood and the screw.
Hides Screws
Countersink drill bits let screws remain level with the surrounding material, but they can also be used to hide the screw’s head.
You can drill the countersink drill bit deeper into the surface so the screw lies under the face of the workpiece. The bit can then be driven even further to make space for a plug, or you can hide the screw head with a filler coating.
Different Kinds of Countersink Drill Bits
Fluted Drill Bits
- Need a pilot hole
- Available in many different sizes
- Two bits and two steps required
Combination Drill Bits
- Combination countersink bits have drill bits within fluted bits.
- Create countersink holes and pilot holes simultaneously
- Available in many sizes
- Single step device
Which Size Countersink Should You Use?
A significant thing you should note with countersink drill bits is that the screw and the bit should match in size.
Fluted Drill Bits
Fluted drill bits are available in several sizes. You’ll need to select one that is the same size as your screw head.
If the countersink hole isn’t large enough, the screw won’t lie level with the external wood. If the countersink hole is too big, there will be room between the edge of the opening and the screw head.
Combination Drill Bits
Combination drill bits tend to be sold in sets. The sets are made to drill countersink openings for popular screw sizes. The screw sizes will be labeled on their containers. You’ll need to select a combination drill bit that’s the same size as the screw.
What If You Don’t Know What Size Your Screw Is?
If you don’t know what size your screw is, place the drill bit’s end over the screw so that it faces the screw’s head.
The correct size drill bit will be the one where the screw threads are just about visible on each of the drill bit’s sides.
Advice For Making Countersink Holes
You may need some practice when drilling holes, as they need to be deep enough to let the screw’s head lie level with the outside wood.
Practice drilling some of these holes on test pieces of wood before starting your project.
Remember that drilling is best done slowly, as drilling fast can result in holes that are too deep.
Try not to drill at very fast speeds, as this can lead to wood chattering. This is where the inside of the opening becomes jagged, while the sides of the hole tearout.
How To Use Countersink Drill Bit: Fluted Drill Bit
You Will Need
- Drill
- Drill Bit
- Countersink Drill Bit Set – Fluted version
- Awl
- Kreg Multi-Mark
- Painter tape
Step 1: Outline The Area
Use Kreg Multi Mark and a pencil to mark where you want the hole to be.
Afterward, make a starting point for your drill with an awl. This will stop the drill bit from moving about on the wood’s surface.
Step 2: Make A Pilot Hole
Select a drill bit that matches the size of your screw.
With your painter’s tape, mark how deep the pilot hole should be. You won’t need to drill this to the exact measurements of your screw. As long as the depth is roughly the length of your screw, you should be fine.
Place the bit into the drill, then start drilling your hole, stopping when the painter’s tape touches the surface of your project.
Step 3: Create The Countersink Opening
Select a fluted bit that matches your screw head’s size. Place the bit into the drill, then start drilling the hole.
Make sure that the hole is deep to let the screw’s head lie level with the wood’s exterior. You can also choose to drill the hole so it’s deep enough to hide with a wood plug or filler coating on top.
Step 4: Turn The Screw
Use a screwdriver to turn the screw inside the countersunk opening.
How To Use Countersink Drill Bits: Combination Drill Bits
You Will Need
- Drill
- Drill Bit Set – Countersink Version
- Kreg Multi Mark
- Awl
Step 1: Outline The Area
Use your Kreg-Multi Mark tool and a pencil to mark where your hole should be.
With the awl, make a starting point for your drill. This will stop the drill bit from moving around on the wood’s surface.
Step 2: Create Your Countersink Opening
Select your combination drill bit that matches your screw size. Adjust it until it matches your screw’s length.
Use a hex key to tighten the screw, then place the bit into the drill.
Start drilling until the hole is deep enough to let the screw head lie level with the wood’s exterior. You can also choose to drill deep enough until you can hide it with a wood plug or filler coating.
Step 3: Turn The Screw
Use a drill or a screwdriver to turn the screw inside the countersunk opening.
You’re done!
The Bottom Line
Countersink drill bits have many advantages. They stop tearout from occurring, improve screw contact, and reduce the risk of wood splitting.
Countersink drill bits are available in two types, fluted and combination. Both of these bits will have to match the same size as the screw being used.
It’s best to practice drilling on practice pieces before your main project. Make sure that you don’t drill too fast, as this can lead to tearout.