How to Drill a 2 Inch or 4 Inch Hole in Concrete

When you have to drill large holes into concrete such as the 2-inch or 4-inch holes, you will need to use a core drill. A standard drill bit is not large enough to make such a hole.

As much as you will be using the core drill, a standard drill is still required in the initial stages to make the guide hole before you can fully switch to a core drill. We will discuss the process later in this guide so keep reading.

Core Drill: What is it all about?

A core drill is simply a drill bit used for making the large holes in concrete and masonry materials. Once you are done with the drilling, it will remove the large center piece to leave you with a large hole.

You will find most core drill bits coming in different sizes such as 2 inches or 4 inches. The size depends on the application. Let us say you want to lay a pipe, duct, or cable the size of the holes will vary. So, depending on the application, always pick the right core drill.

What to Do Before Drilling

It is crucial that you keep some things in mind before driving with a core drill bit. The first thing is to check if there are any hidden cables or pipes behind the point you want to drill.

Get yourself the best cable and pipe detector to scan the wall area to find any hidden pipes or cables. There are many pipes and cable detectors in the market. Some might not find them necessary, but they can save you a lot so that you do not end up drilling into cables that might need additional repair later. Some might even have power running through them leading to more possible dangers.

Which Drill Type Should You Use for Core Drilling

DEWALT Rotary Hammer Drill with Shocks, D-Handle, SDS, 1-1/8-Inch (D25263K)Core drilling is something you cannot just use any drill to achieve the perfect hole in the wall. As a result, it is recommended that you opt for a high powered SDS drill. Such drills are likely to have clutches to help with smooth drilling of such large holes. With the clutch, it is easy to adjust the drill to be as smooth as possible.

Luckily, these drills are not expensive as you might have thought. They start as low as $100 to $200 or more. It comes down to what more features you are looking for in a drill.

If you plan on using a drill more often, then it is better to buy one rather than hiring each time you need one.

For those who think it might be a one-time thing, then consider hiring a drill rather than buying. All the companies that offer drills for hire will have enough knowledge to help you pick the best drill that will make you achieve the best core drill action.

If you have not used a core drill bit in combination with a drill before, do not worry. This is because the process is not complex. It is something we will discuss later in this guide. Also, you can always check out YouTube videos on how to use specific drills to achieve the best hole out of a concrete wall.

The company hiring you the tools from might also have classes where they teach you how to use the tools.

How Does the Core Drill Look Like?

A core drill differs from a standard drill bit in terms of size and appearance. A core drill will be larger and contain a guide drill inside it. The guide drill can be removed once you get ½-inch into the concrete wall. Below, we look at some of the common core drills you can find on the market right now.

1. Bosch HC8510 2-inch SDS Max Rotary Hammer Core Bit

Bosch HC8510 2 In. x 12 In. SDS-max Rotary Hammer Core Bit

Coming from Bosch, we expect this core drill to perform well. It is designed to be perfect for concrete drilling and work with other cutting accessories to get the job done. We found that it’s engineered for performance thanks to having the asymmetrical carbide teeth and a wave design on the outer core drill. As a result, it will be easy to go through the concrete wall without necessarily applying a lot of pressure.

Most people drilling large holes love it for being an all-in-one design. Such a design ensures there is an efficient transfer of power. The result is that you end up with clean and accurate holes.

2. Bosch KC8550 4-inch SDS Max Rotary Hammer Core Bit

Bosch HC8550 4 In. x 12 In. SDS-max Rotary Hammer Core BitThis is another top choice for those who need to make a bigger hole of 4 inches into their concrete wall. The core drill also features a wave design on the exterior. The wave design is important for transferring the power generated by the drill. You will now end up with 40 percent more drilling performance as compared to the previous designs of core drill bits.

This core drill features a carbide-tipped centering bit. The work of this bit is to help you align the core drill to get a clean and smooth hole in the end. The core drill is also designed to transmit more power with less wastage so that you can have a clean and smooth hole once you are done drilling.

How to Drill with a Core Drill

Now that you know what a core drill is all about and the possible options in the market, let us get down to how to use one for drilling in concrete.

Start by attaching the core drill bit to your drill power tool. Do not use a drill with hammer action for core drilling. The core drilling process needs to be smooth so the jerky action of a hammer will make it hard to achieve a smooth hole. Also, it might snap the diamond teeth of the core drill.

With the tool attached, identify where you want to drill. Start drilling slowly with the attached guide drill on the core drill. Once the core drill starts to go through the concrete wall, maintain a smooth low speed. After the core drill has gone through the wall up to about 0.5 inches, it is advisable to unscrew the guide drill bit at this point.

Continuing to use the guide bit might make it to jam as you go deeper into the concrete wall.

With the guide bit removed, you can proceed to drill into the concrete wall up to the desired depth. With the drilling done, when you pull out the core drill, it will come out with the centerpiece leaving you with a clean hole through concrete.

In Summary

It is easy to see that using a core drill is not hard. It is just like using any other type of drill bit to drill a hole into a wall. You can keep an air can around to help with removing any debris that might be remaining in the hole. Since you will be working with power tools always use the right protective clothing and goggles.

The Bosch models we have mentioned above should get you started on how to drill large holes in concrete. You can always get more models depending on the size of the hole you would like to achieve.