A reinforcing bar commonly referred to as rebar, is always lodged in concrete to enhance its tensile strength. For this reason, drilling holes through concrete structures can be a dicey task if one is not careful. For this reason, we are going to give a step-by-step guide on how to drill through rebar in concrete using a rebar cutter without a fuss.
How to Drill Through Rebar: Step by Step Process
Breaking of bits is a common occurrence when drilling concrete reinforced with rebars if the right procedure is not followed and the right bits used. Here we break down the procedure into steps to ensure we get the right result. Bosch SDS MAX 8X concrete and masonry bits are the commonly used bits (characterized by a sharp carbide head). They are a multipurpose bit that are highly versatile to drill the concrete and rebar alike.
Step 1: Wear Personal Protective Gear
It is imperative to wear safety goggles, a face shield and respirators to protect your face when drilling. Dust and small particles of concrete are always produced when drilling concrete which if inhaled can cause silicosis, a lung disease that has adverse long-term effects on your health. Wear industry recommended helmet to protect your head from any falling material. One should also wear industry rated earmuffs or earplugs to protect your eardrums from the noise.
Heavy duty gloves and gauntlets are recommended for use in this scenario to protect your hands from sharp edges and blisters.
Always ensure to wear safety boots that are comfortable to protect your feet from falling objects.
Step 2: Identify the Area You Want to Drill and Mark It
With the help and approval of a structural engineer, determine where the rebar is likely to be found while drilling. This is also an important step to determine whether drilling the rebar will weaken the structure or not.
A rebar detection tool is useful in determining where the rebar is located as most probably the builder did not indicate where the rebars are located. Depending on what structure we are working on, the size of rebar and spacing between them differs. For access roads, an 18-inch grid is used. For terraces, the standard distance between bars is 24 inches. The smallest size of a rebar has a diameter of about 0.375 inches while the largest has a diameter of about 2.25 inches.
Step 3: Selecting the Right Drill
After marking the part to be drilled, we will need to select a drill suitable for the job. Rotary drills and hammer drills are the most commonly used drills. After selecting a drill, we choose a masonry bit and a rebar cutter bit. The masonry bit is attached first and later when we encounter the rebar we attach the tungsten carbide bit. SDS max- 9 speed clean would be perfect for drilling rebars.
Step 4: Start Drilling Concrete
While placing the tip of the drill bit against the mark, we power on our drill and apply pressure gently to start drilling. We drill a pilot hole that will guide the drill bit once we increase pressure. Upon encountering a rebar, you will feel a resistance to the motion of the drill bit. Release the push button and stop drilling. We sometimes lose control of the drill when the tip of the bit encounters rebar, if that is the situation, we drop the drill and move away from it to prevent unnecessary accidents that can cause injuries.
Step 5: Remove Debris in the Hole
Clean the hole using compressed air or vacuum. Once we see the rebar, the next logical step is to determine if it is placed vertically or horizontally. You do not need to be a physicist to do this, trust me. We simply identify if the rebar ridges are aligned vertically or horizontally to the floor. A horizontal rebar will have ridges that are perpendicular to the floor while vertical rebar has ridges that are parallel to the concrete floor layout. After identifying move on to the next step.
Step 6: Take a Coffee Break and Change the Drill Bit
To change the drill bit, we follow the following procedure:
- Take a chuck key and insert it to the chuck.
- Loosen the chuck using the chuck key to release the masonry bit.
- Pick up your rebar cutter drill and insert it to the chuck.
- Tighten the chuck using the chuck key by rotating it in a clockwise manner. When it is secured, remove the chuck key and test if it is working.
Modern drills have a ratcheting mechanism that enables us to apply pressure on the shank of the bit making it stable and strong. Read the user manual to determine whether your drill has this capability. To activate this mechanism, we hold the surface of the chuck and rotate it clockwise. Once in place, we will hear a click sound.
Load a standard rebar cutter drill bit with the same diameter as that of the hole. The best drill bits for use in drilling rebar are;
- Diamond -core drill bits- they are the standard drilling bits for drilling rebar. They are made up of metal coated in diamond making them very strong. They are readily available in different diameters and picking the right diameter for our task won’t be an issue. These bits are compatible with almost every drilling tool. Recommended for drilling large holes. The downside of using a diamond core bit is that once the diamond tips are worn off, they will be ineffective to say the least.
- Drill bits made of tungsten and carbide – this is a new bit type that is made for use in drilling small holes of below 2 inches. Relatively expensive and sizes not readily available.
- Cutter SDS – designed to drill deep holes, they have a strong core that offers a very high resistance to breaks. Designed in a two- stage flute feature with a flexible helix to remove debris. Equipped with four blades made of carbide, it can comfortably cut through a rebar.
- Steel twist Bits – choose this bit if it is the only option available. They are designed to drill thin rebars.
- Rebar bit – specially designed to handle both concrete drilling and rebar drilling. They can be used interchangeably between rotary and hammer drilling. Hammer mode works for concrete while rotary mode for rebar drilling.
Rebar size and spacing influence the bit we are going to select.
Step 7: Start Drilling the Rebar
Start drilling the rebar by applying gentle pressure then increasing it gradually as cutting starts. Ensure that the drill bit and the rebar are aligned to avoid breaking the bit. We encounter some resistance at first but once we have bypassed the rebar we switch back to our masonry bit following the steps in step 6 and continue drilling our hole to the desired depth.
Step 8: Clear the Hole
When we have drilled the required hole size, we remove debris from it using a vacuum cleaner or compressed air depending on which one is readily available. Always drill an extra quarter of an inch to the hole depth to cater for depth taken up by debris. Clear dust from the area using a respirator.
Protecting bits from damage by using it for what is made or will save you a lot of costs by enabling you to reuse the bit in future projects. Following the above step-by-step guide to the latter can make work easier, safer and faster.
Is it safe to drill through rebar?
Whether it is safe to drill through rebar or not, is dependent on many factors. Before drilling through the rebar, it is crucial as mentioned earlier, to let a structural engineer or contractor inspect the structure to determine whether it is safe or not. In most concrete structures, rebars are embedded in them to strengthen the structures. Cutting through rebars can weaken the concrete structure if one is not careful.
The other factor is the type of tool that we pick for the job. Picking the right tool can make drilling through the rebar as safe as it can be by following the right procedure. Here, the means justify the end.
Will a concrete Drill bit go through rebar?
As the name suggests, a concrete drill bit is dedicated to drilling concrete. It will be a huge mountain to climb if we attempt to use it to cut through rebar. Concrete bits are coated with grit that enables it to bash through concrete. Its blunt tip renders it ineffective for drilling rebars. More often than not, concrete bits will wear out or even break when used to drill rebar.
To save time, we go for rebar cutter bits that are specially designed to drill through rebar without hassle. They have a pointed tapered tip with sharp-edged grooves on the shank.
Since concrete is a high-strength material, it is imperative to select the right tools for the task at hand. Work on it slowly but steadily to produce good results. In the event that we are not sure what to do, we consult the manufacturers’ manual supplied with the equipment. Planning before working is a step that should not be overlooked.