Countersunk Screws

A countersunk screw, also known as a “flat-head screw,” sinks into a surface and rests flush in materials. Similar to other screws, a countersunk head screw has ridges that twist into a material to provide fastening power. Countersunk screws have a flat head instead of a rounded or semi-rounded one.

If you’re a contractor, you know that countersunk screws are valuable in woodworking applications to prevent splitting, cracking, gouging and other problem areas. Use a countersunk screw when you want to hide fixtures and maintain the integrity of the material.

Use of Countersunk Screws

Countersunk screws have a wide range of applications. When you countersink screws, you completely bury the head beneath the fastening surface. This burying creates a flat surface that is ideal for many different projects.

One of the most common uses for countersunk screws is securing door frames. Other screw types would protrude from the frame, causing ongoing stress between the door and the frame. Countersinking screws create that flush surface that ensures smooth contact between the frame and the door, helping both pieces function and last for the long term.

Countersunk screws are often found in woodworking and joining applications. The flush surface is excellent for applying screws on items that need to be functional surfaces, like tables and shelving. Countersunk screws can also make it easier to fasten one piece to another even further. While other screws will reach a natural stopping point, countersunk screws can protrude deeper.

Once you know how to countersink screws, you can also enjoy the benefits of finer aesthetic quality. Unlike other types of screws, it’s easy to cover a countersunk screw with a cap or filler that makes the surface sleeker. This capability is especially helpful in furniture making, where fasteners can disrupt the visual quality of a piece.

Countersunk Screw Sizes

The sizes for a countersunk screw vary. The best way to determine size is to measure the threaded part of the screw with calipers. Based on that measurement, you can then select a slightly smaller drill bit to create a pilot hole.

Countersunk Screw Angles

The most common countersink angle for screws is 82 degrees based on the Unified Thread Standard. Countersinks, or tools with a cone-shaped end for modifying an existing pilot hole, are available with various angles to match a particular screw’s head angle.

How to Countersink Screws

A countersink drill lets you countersink screws with two different bit options. Fluted bits require two bits to make a pilot hole and a countersink hole. Combination bits can create both holes at once.

Fluted Bit

With a fluted bit, you use a regular drill bit to make a pilot hole and a second fluted bit to make a recessed area in the shape of a “V” for the screw. The steps involved are as follows:

1. Mark the hole position: Use a pencil and ruler to draw a small X. Consider using an awl or centerpunch to make a starting point for the drill bit.
2. Drill the pilot hole: Pick a drill bit based on the diameter of the screw.
3. Drill the countersink hole: Choose the bit based on the screw’s head size. Ensure that the hole is deep enough for the screw head to be flush.
4. Drive the screw: Use a screwdriver or drill to turn the screw into the hole.

Combination Bit

Using a combination bit, you can make a countersink in less time, with less effort. These tools combine steps two and three together to streamline the process.

Purchase Countersunk Screws at All Points Fasteners

Bookshelves, bed frames and other furniture looks better with countersunk screws. For a clean and professional look, talk to an expert about countersunk screw options today. Reach out to our service team online or give us a call at 800-483-6354.