Concrete cutting is a common task at the construction area, such as cutting concrete floor, concrete wall, concrete slabs and concrete pavers. Although the various concrete cutting saw is available, an angle grinder is the most convenient tool for small concrete cutting work. Besides, an angle grinder is useful for cutting tiles, bricks, granite, marble and other materials.
An angle grinder equipped with a concrete-cutting blade makes straight sharp-edged cuts in a concrete block’s surface. An angle grinder’s design enables it to cut small square holes in a concrete block; a useful trait when installing electrical outlets in a concrete block wall. A concrete-cutting blade for an angle grinder has a diamond-studded rim with ventilation grooves — a tile-cutting blade uses diamond studs but does not have the grooves. The grooves carry the concrete dust away from the rim, which prevents dust build-up around the diamond studs and cools the blade.
In order to complete your concrete cutting tasks safely and efficiently using an angle grinder, it is necessary to take several aspects into account. Here are some tips for cutting concrete with an angle grinder.
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Can I Use an Angle Grinder on Concrete?
Let’s start by saying that an angle grinder isn’t the only tool you can use to smooth out or cut concrete with, but it is the most practical and cost-effective option for DIYers. If your sole occupation doesn’t revolve around you lugging bags of cement around a building site on a daily basis, you might be unaware of what tools of this age-old trade are necessary.
Now while that trusty angle grinder of yours can be utilized to cut through dense compound materials like metal or concrete, it can only do so if you’re using the right wheel. There are two different wheels typically used to cut and smooth out the concrete.
For cutting concrete, you should make use of a diamond blade that can be used for both wet and dry cutting of concrete. A diamond blade is an exceedingly versatile asset to have at your disposal as it can slice and dice everything from stone to granite, brickwork, and even tile.
When attempting to exploit your angle grinder to manipulate such a robust surface as concrete, you need first to fit a diamond cup wheel. This grinding wheel vigorously removes deteriorated paintwork, degrading wallpaper material, glues, epoxy resins, and other surface coatings you like (metaphorically) banished to the shadowland.
So yeah, it’s safe to say that when it comes to assaulting unsightly concrete, you’d like to smooth out or even butcher with the right blade, an angle grinder is perfect.
Choosing right angle grinder diamond blades
First and foremost, You can use dry-cutting blades with or without water, but a wet blade must be used with water. Using water with an angle grinder is not easy because there is no wet cutting angle grinder at all. Generally, there are three types of dry-cutting angle grinder diamond blades in accordance with their rim:
- Segmented rim angle grinder concrete blades have a toothed rim to help eject dust and cool the blade with airflow. One of the risks to the lifetime of a diamond blade is overheating, which affects the bond and can warp the blade. Segmented angle grinder concrete blades are the best option when water is not available. This kind of blades is used for brick, concrete pavers, masonry/block, reinforced concrete, and limestone. Segmented rim diamond blades are typically preferred for cutting concrete with an angle grinder.
- Turbo rim angle grinder diamond blades are specifically designed to get a faster cut speed for both wet and dry cutting. The turbo rim lets air flow pass through its smaller turbo segments to cool the angle grinder disc. The small holes scattered on turbo rim blades are also designed to increase the cooling capabilities. Besides, the angle of turbo segments is designed to help push out the material out. These blades are used for cutting concrete, brick and limestone effectively.
- Continuous rim angle grinder diamond blades are used for cutting marble, granite, porcelain tile, and ceramic tile. It’s most preferred for wet cutting. Continuous rim blades are not preferred to cut concrete with an angle grinder.
How to Cut Concrete Blocks With an Angle Grinder
Layout the cut on the concrete block with a tape measure and pencil. Draw a straight line across the block’s surface at the measurement marks with a pencil, using a carpenter’s square as a guide.
Put on safety goggles, a dust mask and leather work gloves. Angle grinders throw debris and create a lot of dust while cutting concrete blocks.
Turn on the angle grinder. Hold the angle grinder so its blade faces out and the guard faces up. When cutting, the blade will throw debris back toward the handle and operator. This protects the user if the angle grinder drops or binds in the cut — the blade will roll the grinder away from the user.
Score the concrete block’s surface along with the pencil marks with the angle grinder’s blade. Work the blade back and forth across the pencil line until the blade creates a 1/8-inch deep groove. Repeat this on each pencil line.
Cut through the concrete block along with the score marks with the angle grinder. If cutting straight lines completely across the block’s face, cut both outside edges before cutting the centre of the line. If cutting a hole in the centre of the concrete block, work the angle grinder’s blade through the centre of each score mark. Once the blade penetrates the centre of the score marks, work the blade to the corners of the hole.
Flip the concrete block over. Finish the corner cuts and trim any excess concrete from the cut with the angle grinder on the reverse side of the concrete block. Trimming from the reverse side protects the concrete block’s visible surface.
Tips for Cutting Concrete with an Angle Grinder
In order to ensure that you correctly use an angle grinder when cutting concrete, it is necessary to take several aspects into account. This will not only ensure that the project is completed right, but also that it is done efficiently and safely.
Check Your Grip
Prior to using the angle grinder, try it out for grip and test the weight to ensure that you can handle it. Most grinders will have two handles that will help to keep the tool steady, and you should check that you can hold it comfortably with your dominant hand. Be aware that you will need to apply some pressure when passing the blade through the concrete, which will make the tool seem heavier due to the vibrations.
In addition to making sure that the safety guard on the angle grinder is in place and secure, you need to use some other protective methods. Avoid wearing any loose clothing and use gloves to protect your hands and improve your grip. Small particles of concrete can come loose and fly off during the cutting process, which can present a real hazard. Use a pair of protective goggles to ensure that you do not get any debris in your eyes. It is also prudent to wear a face mask to reduce the risk of breathing in any concrete dust.
Mark Cut Line
To ensure that you get a precise cut with the angle grinder, you should mark the position of the line to cut with a straight edge and a pencil. From this point, you should carefully use a hammer and chisel to score along the pencil line, making sure that the resulting groove is deep enough to hold the blade. It should need no more than three blows, depending on the thickness of the concrete, and should be completed along the entire line. This process will ensure that you only cut where necessary, and the blade is not in danger of skidding across the surface.
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Prepare Your Work Area
Ensure that your work area is cleared of any unnecessary items so that you are not hindered while you are using the angle grinder. Besides clearing any potential tripping hazards, make sure that the power cord of the appliance is always to the rear and not in danger of falling in the path of the blade. If you are working in an enclosed area, ensure that it is properly ventilated.
Operate the Grinder Correctly
Make sure that you keep both hands on the grinder when it is on and when you are using it on the concrete. Prior to allowing the blade to come into contact with the concrete, wait for the revolutions of the blade to reach full speed and ensure that you are braced for the change in pressure when you apply the blade. Do not allow yourself to get distracted when you are using the tool and ensure that it is switched off at the power source when it is no longer required.
Although angle grinders were not initially designed with concrete in mind, concrete contractors have found plenty of use for them. Angle grinders are one of the most versatile tools in the concrete contractor’s arsenal.
The tools originally were designed for grinding down and smooth out metal welds by tipping the rotating blade at an angle. This process also works well with concrete, especially for removing stubs or seams.
The tools come in several different sizes from 4½-inch blades up to 9-inch blades. Typically, 4½-inch and 5-inch models feature high speeds up to 11,000 rpm, but they tend to have low torque. They are best suited for grinding off stubs from hardened concrete. They also can be used when tuckpointing, though some manufacturers make specially designed tools for this practice.
Angle grinders play an important role in decorative concrete, whether used for improving the look of stamped concrete, engraving, polishing concrete countertops, or freehand scoring.
The bigger models, ranging from 7- to 9-inch blades, are more powerful tools, with lower speeds and higher torque. These larger models, while they look the same as their smaller brothers, are used for slightly different purposes. Along with occasional angle grinding, these tools can be used for cutting joints, much like a saw. The larger the size, the deeper the potential cut, and they can even be used to cut bricks.
The rat tail angle grinder is a modification on the standard tool theme, except that the tool has a long and tapered body shape and an almost pistol grip. This pistol-like grip provides a more comfortable positioning in hand, says Ryan Anderson, Bosch Power Tools’ product manager for angle grinders. Anderson sees the rat tail grinder slipping into an intermediate position between the larger and smaller tools.
Generally, angle grinders are pretty similar to one another. The features that make any particular angle grinder unique frequently appeal to the user’s preference.
For example, the on/off switch can be either some kind of toggle or slide switch that is clicked on and remains on, or a trigger or paddle switch that a finger activates. Some models have a special feature that ensures the switch isn’t accidentally activated, sending it skidding across the floor where it could injure workers or damage the floor. Some jobs may specify using a grinder with a paddle switch for safety, Anderson notes.
All angle grinders come with blade guards or shrouds that slip over the rotating wheel to keep particles from flying into the air. However, these guards often limit the visibility of the machine; the user can’t see the tool as well. Because of this and the tedium of changing the guards to match the proper wheel leads many users to remove them, which is a safety issue manufacturers advise against.
Whenever you cut concrete, wear sight, hearing and respiratory protection, especially when dry-cutting.
- Make sure that the safety guard on the angle grinder is in place and secure before your concrete cutting work.
- Avoid wearing any loose clothing and use gloves to protect your hands and improve your grip.
- Small particles of concrete can come loose and fly off during the cutting process, which can present a real hazard.
- Use a pair of protective goggles to ensure that you do not get any debris in your eyes. It is also prudent to wear a face mask to reduce the risk of breathing in any concrete dust.
Operate The Angle Grinder Correctly
- Prepare work area for your cutting workwear of potential tripping hazards. Ensure that your work area is cleared of any unnecessary things. Ensure that it is properly ventilated if you are working indoor.
- Mark Cut Line with pencil and chisel to make the straight, accurate cut with the angle grinder, you should mark the position of the line to cut with a straight edge. Then use a chisel to score along the pencil line, making sure that the resulting groove is deep enough to hold the blade. This process will ensure that the blade is not in danger of skidding across the surface.
- Keep the angle grinder steady before using the angle grinder, try it out for grip and test the weight to ensure that you can handle it. Most grinders will have two handles that will help to keep the tool steady, and you should check its stability and make sure you can hold it comfortably with your dominant hand.
- Keep both hands on the grinder and wait for the blade to reach full speed and ensure that you are braced for the gradual change of the strength. Now apply some pressure to pass the blade through the concrete. Don’t force the blade into a cut. Make a series of gradually deeper cuts to avoid overheating the blade.
- Ensure that it is switched off at the power source when it is no longer required.
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Cons of cutting concrete with an angle grinder
Certainly, an angle grinder has sufficient power to cut concrete materials. But it will probably perform poorly compared to a wet.
A walk-behind concrete saw uses water to keep diamond saw blade cool, but there’s not cool water component in angle grinders. The consequences of this are that your diamond blade would wear quickly when cutting an extremely hard substance such as reinforced concrete.
If your concrete cutting work is occasional, a manual angle grinder works fine for light-duty cutting work. A concrete saw is essential for heavy-duty concrete cutting.
So hopefully you’ve gained some valuable new insight on the correct method on how to use an angle grinder to smooth concrete surfaces. With the right tools and personal protective equipment, you’ll be able to smooth and finish any unsightly looking concrete surface with a bit of practice and perseverance.
For you to achieve absolute DIY grandeur in the concrete resurfacing department, you’ll simply have to test your patience until you possess the adequate skills. Keep in mind that if this is your first time attempting a resurfacing or smoothing job around the home, that concreting is an actual trade that individuals have spent years mastering their craft in.
So, work safely and efficiently, and don’t be afraid to ask for help from a beer buddy that you could probably compensate with more beer for services rendered.