Cutting metal with a grinder - basic rules: how to cut correctly

Cutting metal with a grinder (angle grinder, angle grinder) is the easiest way to process various hard materials, including metal workpieces. This tool is used to clean and cut reinforcement, round timber, pipes and profiles of various types.

Photo No. 1: cutting metal with a grinder

Many people are interested in what is more profitable to cut metal: with a grinder or with gas. The answer depends on the scale of processing. In general, the cost of consumables when cutting metal products with an angle grinder is higher. However, in domestic conditions, when processing medium and small-sized rolled metal, the purchase of special machines is unprofitable. Gas cutting is more often used in large industries. In addition, edges treated with an angle grinder are more accurate, without the formation of scale and oxide.

Photo No. 2: gas cutting of metal

Further in the material we will tell you how to choose a tool and consumables, how to use an angle grinder correctly and what safety measures need to be followed.

Device Features

The simple design of an angle grinder does not prevent it from being one of the most popular and necessary tools in the household.
The principle of operation is an electric motor that drives the shaft through an angular gearbox, onto which a special disk is attached. The main advantage of this technique is its versatility, because when using various discs, cutting, polishing or grinding off excess material is performed. There are discs designed for working with wood, but they cannot be used for metal. Discs with an abrasive base of different grain sizes are used as polishing consumables.

Bulgarians are classified into several types:

1. Professional;
2. Low, medium and high power;
3. Without handles;
4. Household;
5. With one or two handles.

Low-power equipment is powered from a simple household socket of 220 V, but powerful angle grinders are connected to a network with a voltage of 380 V. Regardless of the power, all machines perform manipulations such as cutting, grinding and polishing wooden, concrete, metal and plastic materials.
The only difference is the operating time. Powerful equipment can work longer without overheating, but household equipment must be given a rest. If necessary, an angle grinder serves as the basis for creating a small machine. To do this, the grinder is fixed permanently and parts, drills, cutters are turned and knives are sharpened.

The grinder is an indispensable equipment for construction and rescue work in auto repair shops and economic activities.

There are several reasons why an angle grinder is classified as a dangerous tool:

1. Working with an angle grinder often takes place on an unstable surface, where it is impossible to find support for a stable position.
2. Although protected, most of the rotating disk is not protected.
3. Abrasive polishing discs often break during operation into medium and small pieces, which fly off in different directions at great speed.

Operations that can be performed using an angle grinder

The grinder is a multifunctional tool. The drive mechanism in it is an electric motor, which through a gearbox transmits movement to a shaft with a replaceable attachment attached to it. The general view of the device is shown in the photo below.

There are models on the market that differ in power and design:

• household;

Angle grinder (grinder) FT-1318

• professional;

Professional large angle grinder 230mm Stern AG230B

• with or without handles.

Powerful devices are powered by a three-phase voltage of 380 V, and household devices are powered by a single-phase 220 V network. Low-power battery models are also available.

An angle grinder (angle grinder) can do the following main types of work with various materials:

• cutting;
• grinding;
• polishing.

If you fix the grinder motionless, you can sharpen various tools on the wheel: cutters, drills, knives, etc.

The angle grinder is designed to work with the following materials:

• concrete;
• metal;
• tree;
• glass;
• ceramic tiles;
• stone;
• brick;
• plastic.

Grinders have become widespread both in everyday life and in industrial settings. This is due to their wide functionality, due to the following factors:

• a large selection of different attachments from different materials to perform various operations;
• Possibility of fixed fixation using special fastening devices;
• the presence in some models of additional handles and several speed modes of operation.

At the same time, you must always remember that only special discs are used to process each material.

Grinding with a grinder

First of all, let's figure out how to grind with a grinder, and what attachments are used.

For grinding and stripping, grinding discs, cups, wire meshes of various shapes and other devices are used. Both made entirely of abrasive material, and those having a steel or plastic base, onto which various abrasive pads and even sandpaper are attached.

Grinding with a grinder

The cleaning disc is noticeably thicker than the cutting disc. Its shape can be flat or dish-shaped. If such a “plate” is deepened and the edges are made narrow, we get a cup-shaped grinding attachment, or simply a “cup”.

We grind the entire plane of the nozzle or part of it. In this case, the axis of rotation is located almost perpendicular to the surface being processed.

Advice

. When grinding, it is better to rotate the front rotary handle of the angle grinder (if equipped) so that the axis of the handle coincides with the direction of the axis of rotation of the attachment. It is usually more convenient to work with a grinder when your hand is not on the side, but above the attachment, especially on surfaces of complex shape.

Cutting brick, concrete, metal with a grinder

Now about how to cut brick, concrete, metal, etc. with a grinder. For this purpose, special wheels are used, which are called cutting wheels.

A grinder can cut both metal and brick

They come in two types: for metal and for stone. If absolutely necessary, you can cut metal with a disc on stone and vice versa, but the productivity of the process will be lower.

In addition, if there are no problems with abrasive disks, then a steel disk with coating or inserts, designed for cutting stone, will quickly fail if it is used to cut metal.

Important!

It is strictly forbidden to cut thick wooden boards and logs with a grinder. It is even more dangerous to do this by installing a circular saw blade on the grinder. Unfortunately, such a violation is quite common and the consequences are sometimes quite tragic.

Cutting is performed using the edge of the disk, and the pressing force should not be significant; the tool must be held practically “in weight” and without distortions.

It is allowed to cut wood using an angle grinder using a special disk for wood. They are fairly new and commercially available.

Wood disc for grinder

Grinding with a grinder

Builders call a groove a channel cut into a wall, ceiling or floor to accommodate communications.

Let's look at how to groove with a grinder, since this type of work, although it is performed with cutting wheels, has its own characteristics.

To create a groove along its width, use a grinder to cut two parallel lines of the required depth, after which the material between them is selected using a hammer drill or a chisel with a hammer.

To work on concrete or ceramic bricks, it is better to use a steel disc with diamond coating or cutting inserts. Plaster, especially lime or gypsum, can be easily cut with a regular stone abrasive disc.

Gritting using an angle grinder

The work is noticeably simplified if you cut the grooves with a grinder with a special attachment - a wall chaser. This nozzle has two discs, the distance between which can be adjusted and cuts neat parallel lines in one pass. You can find out more about the methods of cutting channels for wiring in the wall → by following the link.

Cutting a round hole in metal using an angle grinder

In practice, it is often necessary to cut a circle in metal, and the only tool available is an angle grinder. But it is quite enough for this purpose. The algorithm of actions is as follows.

1. Draw a circle with a compass on the surface of the metal or on a pre-made paper (cardboard) template with chalk or a marker.
2. Holding the grinder at an angle to the surface of the sheet, make a preliminary marking cut of the metal along the marked contour, making short movements with the disk (sawing in small sections).
3. Then, moving the nozzle in the same way, deepen the slot until it is completely cut out.

You need to cut along the outer contour of the circle so as not to reduce the size of the circle. If its diameter is small, then they cut by touching the metal with a disk point by point (without longitudinal movement of the nozzle). The round hole will have an oblique cut, as well as some minor flaws (they depend on the skill of the worker). Afterwards it is processed, if necessary.

The entire process of cutting a round hole in sheet metal using a special tool is shown in the video:

What are the dangers of an angle grinder?

An angle grinder is a dangerous tool. This is caused by the following reasons:

• high rotation speed of the working nozzle - it exceeds 10,000 rpm;
• openness (unprotected by the casing) of most of the disk;
• the ability to break the abrasive disk into fragments of different sizes, which fly to the sides at considerable speed;
• frequent inability to properly organize the workplace;
• the formation of small particles when cutting metal (or other material) or grinding.

When the disk jams, which occurs even due to its slight misalignment, it is almost impossible to hold the grinder in your hands, especially a powerful tool. This is caused by the high speed of rotation of the nozzle. Therefore, beginners are recommended to work with low-power models equipped with discs with a diameter of 115-125 mm. The latter must be free from the slightest defects that could lead to their sudden destruction and tearing of the angle grinder out of your hands with uncertain consequences.

Disc selection

The diameter, thickness and type of disks are selected depending on the planned type of work. Diameters vary from 125 mm (small) to 250 mm (large, the most common) and affect the size (thickness and depth) of the cut.

A grinder for cutting metals requires a cutting disc with a thickness of 1.0-1.2 mm (professional ones reach 2.5 mm). Curly carving on thin metal requires the use of a disk with a small diameter or one that has already been used.

When cutting using discs of any diameter, it is necessary to use a protective coating - a casing. Essentially, this is a shield needed to catch small metal scraps generated during the cutting process.

Options for cutting and cleaning discs for grindersSource prom.st

How to cut correctly

First of all, you need to pick up the instrument correctly. Right-handed people hold the grinder with their right hand by the body. In this case, the circle is located on the left, and the gearbox is on the right side of the machine. With your left hand you need to hold the tool by the handle, which is screwed into the body. The correct position of the handle is up. The guard should cover the blade and hands, dispersing sparks away from the worker. For left-handers, the handle is screwed into the other side of the body, the protective casing is rotated and secured in the desired position.

Tool manufacturers give three main tips for working with an angle grinder: hold firmly with your hands, do not be on the cutting line, stop and do not start the machine if the disk is jammed.

How and in which direction to cut, everyone decides for themselves, taking into account the fact that when biting, the grinder is thrown in different directions.

Rule #1: Adjustable Handle Position

The handle should be on top. Many craftsmen screw it in from the side, in a horizontal position, claiming that this way the cutting area is better visible, and therefore higher safety, but this is a dangerous misconception. Only with a vertical position of the handle on top is it possible to ensure a strong grip and protect yourself and others from the situation when the grinder flies out of your hands when you “bite” the disc.

The handle should be located on top - this will ensure a secure grip.

Many will ask why the lateral position of the handle is provided in this case. It is used during grinding work, when there is no danger of the disc being “bitten” by metal parts.

Rule #2: Direction of disk rotation

Inexperienced craftsmen often believe that the blade should rotate, making the cut "from itself" so that the sparks fly away from the operator. However, not a single specialist who has experience working with angle grinders would agree with this statement. The fact is that a special casing protects from flying sparks, so the master is not afraid of them. Here the question arises differently: how will the grinder behave if the disc is “bitten” by metal?

When rotating towards itself, the jammed disk that suddenly stops causes the angle grinder to be pulled out of the operator’s hands towards the ground, i.e. away from the master. If this happens during reverse rotation, “from itself,” the angle grinder may fly into the head of the person working with it, which at best will be very unpleasant, and at worst is fraught not only with a hospital bed, but also with more dire consequences.

The disk should rotate towards itself. The protective cover will prevent sparks from flying into the eyes, and use will be safer

Rule No. 3: positioning the metal when cutting it

Many novice craftsmen make a serious mistake by fixing the pipe or channel being cut on both sides and starting cutting between the fasteners. With this arrangement, there is a high probability of the disc jamming at the end of the cut. For example, we can recall an ordinary board that everyone sawed at least once in their life. In the end, the hacksaw gets jammed and you have to look for a position that will lead to the opposite effect. It's the same story with pipes. One end should be suspended. In this case, decompression will occur, not jamming.

Important! Monitor the condition of the disc edge. At higher RPMs, a small chip can cause the wheel to fly apart, causing serious injury.

The edge of the part should be suspended - this will prevent the disk from jamming

Rule No. 4: Using the side of the disc is prohibited.

Many “craftsmen” claim that sharpening drills with the side surface of a cutting wheel is completely safe. Sometimes such delusion can cost lives. After all, the circle itself consists of an abrasive, which is reinforced on both sides with a metal or fiberglass mesh. If the reinforcing layer is damaged, the abrasive may not withstand the rotation speed and break into pieces. That is why only the end surface is considered working.

Also, do not use a metal cutting wheel to cut wood. Despite the fact that this material is softer, when the circle rotates, its temperature rises sharply, which first leads to the appearance of smoke, and as work continues, to the melting of the adhesive base of the disc. The result may be its destruction, which, again, will lead to injury.

Working with the side plane of the disc is prohibited

Rule No. 5: nuances of working with an angle grinder

When installing a disc on an angle grinder, many people try to thoroughly tighten the nut using the wrench included in the kit. This is a big mistake. This key is intended for unscrewing only. The installed disk just needs to be tightened manually. The grinder is designed so that the nut is tightened during operation. Therefore, using a wrench during installation will lead to difficulties, and sometimes even to the impossibility of unscrewing the nut later.

It is worth paying attention to the launch of angle grinders. The button should only be pressed if there is nothing obstructing the disk. This means that under no circumstances should the wheel be immersed in a started cut before it unwinds and enters the rotation cycle.

The nut must be tightened by hand - no wrench is used.

To yourself or from yourself

The most common question that plagues many angle grinder owners is “how to cut correctly with a grinder so that the disc rotates away from you or toward you?” There are many opinions, and everyone proves their point of view. But there is only one correct answer: “you can cut both from yourself and towards yourself.” A clear proof of this is the presence of holes for the handle on both sides of the device. In general, it all depends on individual preferences; whoever is comfortable with it, cuts it that way. However, each method has certain nuances that should be taken into account.

Push

Many owners of grinders do not like and cannot even cut from themselves. The bottom line is that this method rarely forgives mistakes. Any inaccuracy or crooked cut leads to clamping of the disc and its rupture. I want to say that I have a friend who is used to cutting himself, and taking my grinder in his hands, he destroyed two discs and left screaming. This is a person who has been working with angle grinders for about 10 years. There is also a myth that when you cut away from yourself, if the disc jams, the grinder will fly into your stomach. I want to say that if you don’t hold it properly in your hands, then it can even fly away from the workshop. The advantage of cutting metal from yourself is that sparks fly from the grinder and it is possible to see the product better. In addition, if the disk ruptures, it will fly away from you.

To myself

Cutting metal with the blade turning towards you allows you to work with an angle grinder, excuse the expression, with a little negligence. But you pay for such convenience with sparks flying into your eyes and feet. If the protective cover is not positioned correctly, the risk of burning your pants increases exponentially. In addition, the product is much less visible, and if it ruptures, the disc can fly under your feet. When cutting metal using this method, I recommend holding the angle grinder in such a way that if the disc jams and ruptures, the latter cannot hit the leg or other part of the body.

The nuances of cutting some materials

When cutting concrete, follow these recommendations:

• before work, check for the presence of pipes, fittings, and electrical wiring embedded in concrete (with a metal detector or devices for searching for wiring);
• to reduce dust, the work surface is moistened with water (for example, from a spray bottle or a brush);
• periodically cool the cutting element with air or water.

In the absence of a tile cutter, a grinder can also be used to cut tiles. Experts even cut circles into the tiles. Stone and tiles are cut in two ways:

• wet (wet the work area with water);
• dry (without moisture).

How not to work with an angle grinder

Safety precautions when using angle grinders should come first. According to it, it is prohibited:

• perform work manipulations without PPE;
• works in light clothing that does not completely cover the body (arms, legs);
• use a machine that is not equipped with a casing to protect against sparks;
• without checking the functionality of the tool at idle, start using it;
• work with a disc that is defective or unsuitable for the material;
• be located in the cutting plane;
• press hard on the tool;
• work so that the direction of rotation of the circle is towards the operator;
• perform work without taking breaks, because your hands get tired and it’s difficult to hold the grinder tightly;
• so that the workpiece being processed is not fixed (for example, in a vice or clamps);
• use the side of the disc to sharpen metal parts;
• cut workpieces whose thickness exceeds half the radius of the circle used;
• presence of unauthorized persons in the work area;
• touch the attachments until they have cooled down, because they become very hot during cutting and grinding due to friction;
• when deepening the circle into the workpiece, turn on the tool;
• grind with thin discs;
• use nozzles with a larger diameter than the angle grinder is designed for;
• position the workpiece so that when cutting, the circle is clamped (the cut should be for breaking, not for squeezing).

Safe use of the saw in an angle grinder is ensured by the fact that it is replaced only when the device is disconnected from the network.

Recommendations for cutting metal pipes

Cutting pipes from different metals is a popular operation when carrying out repair and construction work. Products have to be cut off when installing sewer and heating systems and water lines. In this regard, the grinder copes well with various tasks. Discs for work are selected according to the material from which the pipe is made.

Using an angle grinder makes it possible to:

• sawing pipes at different angles, for example 45 and 90 degrees;
• cut large diameter products;
• cut profile (rectangular or square) pipes smoothly;
• perform longitudinal cutting of tubular blanks;
• sawing cast iron pipes;
• cut thin-walled tubes.

If you need to cut a large diameter pipe, then using a grinder allows you to complete this work without significant financial costs. But at the same time, labor productivity is low, and the risks are considerable. When long pipes lie on supports, only the hanging parts are sawed off. If you cut in the center, the cutting edges will jam the cutting wheel, which will lead to jamming of the tool and possible injury.

Specialists not only cut pipes from different materials at the required angles, but also cut holes of the required shapes in them. Work with profile and round workpieces is carried out in a similar way, with mandatory observance of safety regulations.

Sawing pipes at different angles

It is necessary to cut round and profile pipes at an angle of 45 and 90 degrees when laying various communications. In any case, it is necessary to saw off the pipe evenly so that the elements that need to be connected are connected to each other as tightly as possible.

A cut at an angle of 45 degrees for cylindrical pipes is carried out as follows:

• take an ordinary square sheet of paper;
• fold it exactly diagonally;
• This template is used to wrap the pipe;
• use chalk or other marking device to mark the future cutting line;
• remove the template;
• clamp the workpiece in a vice;
• cut off the marked piece of pipe.

When applying the template, either of the two short sides of this triangle should be parallel to the central axis of the pipe.

When it is necessary to cut at an angle of 90 degrees, the pipes are simply wrapped in a circle (cylindrical) or around the perimeter (profile) with a sheet of paper. After this, mark the cutting line. You can also mark a profile pipe very simply using a regular square.

If it is necessary to cut a significant number of profile pipes at an angle of 45 and 90 degrees, appropriate templates are made from this material, only with a larger cross-section. This allows you to perform the required measurements only once. In this case, a construction square or a protractor is used for initial marking. When the template is made, the cut pieces are inserted inside it, marking the cut lines. Then sawing is done.

Templates are also made for other angle values. This method increases labor efficiency.

Features of cutting cast iron and thin-walled pipes

Cast iron is a brittle material. To cut a cast iron pipe with a grinder, proceed in the following sequence:

• mark the cutting line;
• place a wooden block under the pipe, which will serve as a support for it;
• make a cut along the contour several millimeters deep;
• insert a chisel into the recess made;
• the instruction is hit hard and sharply with a hammer.

After the impact, the pipe will split along the cut line. Its edges will be quite smooth. If necessary, they are further processed.

To perform longitudinal sawing of a pipe, accurate marking is also important. To apply it, various devices are used, for example, construction thread (“beat”). The entire sawing process should be carried out carefully, slowly, so as not to stray from the marked line.

Thin-walled pipes are one of the varieties of this type of product. They are often made of non-ferrous metals: copper or aluminum. Cutting them is a difficult task. In this case, you should use grinder wheels that match the material of the workpiece.

Sawing thin-walled tubes must be done very carefully, because they can easily become deformed even when a slight load is applied.

To reduce the likelihood of bending of the cut part, various bulk fillers are poured inside it, for example, ordinary purified sand.

Basic rules for safe work when cutting metal with an angle grinder

Layout of the most dangerous sectors when working with an angle grinder, taking into account rebound and destruction of the disc.

The most necessary condition when cutting is strict adherence to safe work rules.

Manufacturers of angle grinders are constantly trying to minimize the risk of injury and injury by inventing and improving various protection systems. But no one will take care of the employee like he himself.

The main dangers that arise when cutting metal are the flying out of fragments of a broken disk, a flow of sparks and tiny abrasive particles, and the inability to hold the tool in your hands.

If the disk breaks or gets jammed, the angle grinder can break out of your hands at the most inopportune moment and with great force, so even before starting work, you should foresee the direction of its possible movement.

Safety rules cannot be neglected even when performing minor work.

Before starting work you should:

1. Protect your face, eyes, hands and, if possible, all parts of your body.
2. Remove all flammable materials and objects that are in the direction of the sparks.
3. If possible, secure the part being processed with a grinder in a vice. It is prohibited to hold the workpiece with your free hand or press it with your feet.
4. If you are installing a new disk, you need to “scroll” it with a grinder at maximum speed, placing it further away: the disk may turn out to be defective and fly into pieces.
5. Install, adjust and secure the protective cover.

It is best to protect your face with a special shield when working with an angle grinder.

During work you should:

1. When replacing disks during rest, you must disconnect the angle grinder from the network.
2. Use goggles or a face shield to protect your eyes and face—professionals use both during long periods of work.
3. Hold the grinder firmly during all work.
4. To replace the disk, you need to wait until it stops completely.
5. Work in protective gloves. It is not advisable to use cotton mittens; they do not provide sufficient protection, they can catch fire, and the threads can wrap around the grinder spindle or disc.
6. During work, you need to position yourself so that your face, and, if possible, all parts of your body, are not in the plane of rotation of the disc.

Upon completion of work you should:

• wait until the rotation of the disk has completely stopped and only after that put the tool on the floor with the disk facing up so as not to damage it;
• disconnect the grinder from the network;
• make sure there is no smoke or other signs of fire.

A typical mistake made when cutting metal: if the diameter of the new circle is larger than the size of the protective casing, it is removed. The casing is a protection in case the disk breaks and falls into pieces during metal cutting.

Instead of a disk, many people use cutters, saws or other available materials. Doing this is strictly prohibited.

Individual protection means

The name PPE, or personal protective equipment, refers to means for personal use that are used to protect against pollution, prevent or reduce the effects of harmful and dangerous factors. For most workers, this is workwear appropriate to their profession. It usually includes trousers, a jacket, a hat, and closed shoes. Since the grinder is a tool of increased danger, clothing is supplemented with other means of protection:

• glasses or shield;
• anti-noise headphones or earplugs (ear plugs);
• vibration-isolating gloves;
• a respirator, especially when cutting stone, tile, concrete or slate.

Precautionary measures

An angle grinder is a dangerous tool. When working with it, a number of conditions must be observed:

1. Do not use the tool without safety glasses;
2. Before starting cutting or polishing, check the suitability of the disc at idle speed;
3. Clothing should cover your hands and protect from hot sparks;
4. Do not remove the protective cover from the angle grinder;
5. When cutting on a plane, the master and assistant should be on the side of the tool;
6. The unit cuts material under its own weight, and excess load will lead to deformation or jerking;
7. Working without a break leads to overheating of the equipment and fatigue of the master, who must hold the grinder firmly in his hands, observing the cutting angle;
8. The workpiece to be processed must be firmly secured;
9. You cannot grind parts with the side of a cutting disc, because there are specialized wheels for such work;
10. Within the work area there is a master and his assistant. All other people move to a safe distance;
11. The radius of the cutting wheel should correspond to 1/6 of the thickness of the workpiece.

Cutting pipes at right angles

The technology for cutting at right angles is quite simple. You just need to fix the metal part, mark the cut line, and directly cut the workpiece. The end of the cut part of the pipe should be above the support.

To mark the cut, use wide or narrow tape, a marker or a simple pencil. You just need to wrap the product, mark the cut location, and make an even cut. When winding, both ends of the tape must fit together accurately