Now drilling holes large diameter in metal is not serious problem . The main thing is to prepare well. Let's say you need to make a hole in a corner, channel or mortgage to strengthen building structure or hang a shelf, light fixture or conduit. That is, to do this not in a workshop or workshop, but directly on site. The easiest way to drill in such conditions is to use an electric drill. But, imagine how much pressure needs to be applied to it to drill a hole with a diameter of 16 or 20 mm? The question is not rhetorical - the force will be about 40-50 kgf. This is not at all easy to achieve if the proposed hole is located above the level of the driller's shoulders. Even 10 years ago, when such a task arose, even professionals resorted to autogenous and, just imagine, drilling small holes around the circumference of a large one. Today there is a completely professional solution for this - core drilling, which ensures the production of holes of 11 quality.
However, many are sure that core drilling is a rather expensive method, economically beneficial only for industrial volumes. Is this statement true? Partly. Today, you can choose several options for tools and equipment for drilling holes in large-diameter metal without drilling. In this case, the cost per hole will be justified even when drilling only a few holes.
Let's consider What tool options for drilling large-diameter through holes in metal does the market offer?. For comparison, we take a diameter of 51 mm.
Firstly, this bimetallic crowns. We have a choice of samples from the cheapest ones, which are immediately sold in sets and cannot be accepted by us in this review for the reason that their purpose is to drill out wood, and even if they can drill through a sheet of metal, it will not be thicker than 0.5 mm . At a price of 240 rubles, products with a wall thickness of 1-1.2 mm start, often marked HSS -Co 5% and even HSS -Co 8, but judging by the fact that drilling one hole in stainless steel takes more than one such crowns, there may be no cobalt there at all. Twice as expensive bits of more decent quality, which really allow you to drill stainless steel and ordinary steel a few millimeters thick. Bimetallic crowns This level allows you to drill 5-20 holes in a steel sheet 5 mm thick. At the same time, the use of any lubricant-cooling composition ensures that the upper limit of this range is achieved. At the third stage there are bimetallic crowns worldwide famous brands, which are still twice as expensive, can be equipped with special devices for quick change in the drill, but their service life is not much or does not exceed the average price level.
Drilling large diameter holes in steel sheets thickness of more than 5-6 mm for bimetallic crowns is very difficult, although sometimes you can hear a different opinion. It is based on data on the full drilling depth of such crowns - 35-38 mm. As a rule, only sellers of bimetallic crowns, who do not have a more worthy tool in their assortment, risk advising drilling a 30 mm sheet or beam in this way. The fact is that the bimetallic crown does not have a chip removal groove, and as soon as the thickness of the metal being drilled becomes greater than the height of the crown tooth, problems with chip removal begin. In addition, the body of the bimetallic crown is not entirely cylindrical in shape, which causes jamming in metal of considerable thickness.
Unlike bimetallic crowns, they provide more accurate drilling. Carbide body hole saw- turned, while the bimetallic crown is rolled from tape and welded into a ring. There are several types of carbide drill bit designs. Without delving into the types of shanks and types of fastening, we will only analyze the cutting part. The most expensive part of the crown is the carbide teeth. The quality of the material greatly influences the drilling speed, impact resistance, bit life and the ability to drill alloy steels with a high chromium content.
The second feature that you need to pay attention to is the shape of the tooth and its size. For drilling thin sheet steel, thin stainless steel and non-ferrous metals, a narrow tooth with a flat profile, slightly beveled inward, is used. Such crowns also do not have a chip removal groove, and they will not be able to drill into metal thicker than the height of their tooth. The price of such crowns is two to three times higher than that of bimetallic crowns, depending on the design of their body, they can be designed or. Since these are professional samples, at present their counterfeits are rare, and almost all samples found on the market are of acceptable quality, but excellent quality ones should be chosen from manufacturers specializing in these products.
Thicker metal can be drilled. In such crowns, every second or, as a rule, one of three consecutive carbide teeth is sharpened in its own way. This ensures soft cutting, no vibration, reduced load on cutting edges and, as a result, an increase in the resource of the crown. Such crowns have a short or long chip removal groove that extends almost the entire height of the wall. The first version of the crowns allows you to drill metal up to 12 mm thick, and up to 25 mm thick. It is this version of the tool for drilling holes in large-diameter metal that is the most progressive, providing the best performance and quality. The price of such crowns is 20-30% higher than that of thin-walled ones and in absolute value is 1880 - 1910 rubles, as we agreed, for a crown with a diameter of 51 mm. As everywhere in nature, there are deviations in one direction or another up to 2 times, but, as usual, consideration builds a golden mean.
An option in which the metal is quite thick, say 10 mm, and the hole diameter is 20-25 mm can be solved. It is recommended as a drive, but you can also use an electric drill. With the mentioned machine, the investment will be 21,164 rubles excluding VAT, and with a drill - 5,000 - 5,500 thousand.
For a hole with a diameter of 50-60 mm, with such a metal thickness, the use of a magnetic or stationary drilling machine is clearly required. A large load determines the high cost of investing in equipment, and together with a crown it will be about 56,000 rubles, or, option with magnetic drill stand and a separately purchased drill about 50,000. Drilling such holes with a drill by hand is not only difficult, but also dangerous.
Drilling large-diameter holes in metal up to 5 mm thick with a hand-held electric drill is not difficult when using both bimetallic and carbide bits. The choice of tool depends on the required accuracy. When drilling holes with a bimetallic crown, the ovality of the holes and the increase in diameter from the desired value can reach 4% or in absolute terms - 2 - 3 mm. When drilling with a carbide crown - only 0.6 - 1 mm. In addition, all of the carbide bits presented in the review, and almost all of the bits available on the market for metal, also drill stainless steel.
In this simple way you can not only round hole in hardened steel, but also a hole of any other shape in without extra effort. Chemical method will help you out and make the task easier. The method does not require expensive chemical reagents, all ingredients can be found in any household.
Will need
I offer a simple method for making holes in high-speed steel. To work you will need:- any product made of high-speed steel;
- marker;
- nail polish;
- nail polish remover (can be replaced with white spirit or acetone. I chose the remover only because of the pleasant smell, and it’s the same acetone);
- cotton wool;
- empty plastic container(bottle);
- salt;
- a homemade device made from a charger and two nails.
Making a hole in metal without a drill
Apply nail polish remover to the cotton wool and degrease the surface of our workpiece.
Apply varnish to required area. The varnish must be applied in a thick layer on both sides. Don't forget to coat the ends thoroughly. Leave the workpiece for 10-15 minutes to allow the varnish to dry.
On the dry surface, with a marker on both sides of the workpiece, I mark the place for the hole. I choose the location arbitrarily, now I need to show how you can make a hole using this method. For example, you need to install a regular factory rivet. The hole diameter should be slightly smaller size rivets.
Then use a knife to remove the varnish inside the hole outline. Do this on both sides.
Pour water into a container and add 3 tablespoons of salt. The height of the water in the container should be 10 mm less than the height of the varnished area of the workpiece.
I take a device made from a hair clipper charger and two nails. The nails will serve as electrodes - I connected them to one contact. The other contact is simply bare, stripped wire. I use Charger 12 V, but a regular mobile phone charger will cope with this task.
The stripped wire should be positive, the electrodes should be negative. We attach the positive wire to our workpiece using a clothespin. Then we lower the nails into the water.
You can make slits in the container to fix the position of the nails. Plugging the charger into a power outlet. After switching on, the water around the electrode nails begins to bubble, and the cleaned hole mark turns black.
Note: to check the polarity of the wires, you must connect the charger. If water starts to bubble around the nails, it means it's a minus and you connected correctly. The appearance of bubbles in the water around the workpiece indicates that the minus is connected to it and the wires need to be reconnected. The negative must always be connected to the electrodes, the positive to the workpiece being etched!
Leave the container for one hour, 30 minutes after the start of the process you need to change the water. I turn off the charger and take out the workpiece.
A through hole appeared in the intended location. In order to make the hole diameter larger, the process can be continued. Or file uneven edges with a file.
This is how you can make the desired hole in a workpiece by etching high-speed steel using the most ordinary objects.
Metal processing is carried out not only in industrial conditions. By doing repair work on a car, manufacturing structures for personal plot or carrying out home renovations, it is necessary to drill holes in the metal. At home, a hand drill is most often used.
This universal tool Requires certain skills in working with solid products. You can purchase or make your own machine for drilling holes in metal, but this is not a cheap pleasure.
The technology of drilling holes in metal involves removing a thin layer of material through simultaneous translational and rotational motion.
The main condition for high-quality and safe (for the tool) processing is keeping the chuck axis in a fixed position. Using the machine it is easy to maintain straightness, which cannot be said when working with hand tools.
If you are not confident in the steadiness of your hands (this is a normal situation for an ordinary person), mechanical assistants (jigs) are required for drilling at right angles.
Let us immediately make a reservation that additional conductors are required only in the case when the thickness of the metal exceeds the diameter of the drill.
If you are making a hole in a thin steel plate, straightness does not matter.
There are several types of guides for hand electric drill. Power-driven tools are not suitable for working with metal, especially if we're talking about about accuracy. 
- Drilling jig. Made in the form of a housing, convenient to hold, inside of which guide bushings for drills are located various diameters.
- Guide for drill (manual). Supporting device in which the instrument is fixed by the neck
- Drill stand (semi-stationary). In fact, it is an inexpensive alternative to a drilling machine.
The material of the bushings is harder than the tool, so the holes do not wear out. By installing the jig exactly above the center of the intended hole, you don’t have to worry that the drill will “lead” away from the given direction.
This device is especially useful when drilling perpendicular holes in pipes of small diameter, when the tip tends to slip off the cylindrical surface. 
The sole is placed on the workpiece, held by the handle with the second hand. The drill moves strictly vertically, preventing distortions and drifts of the drill.
The design can have a corner holder for small-diameter pipes, which makes the device more versatile.
With a rotating mechanism, you also get a device for drilling holes at an angle. 
True, it will not be possible to drill metal in this way; lateral loads will quickly break the drill.
Today everyone home handyman available necessary tool for metal cutting, drilling, stripping. But what if you need to drill a large diameter hole? After all, the maximum cross-section regular drill for a hand-held electric drill it is only 20 mm.
Tools for drilling large holes
There are several ways to drill a hole with a diameter greater than 20 mm. For this, special devices are used:
- Cone drill. A large number of It will not be possible to drill openings of the same size. But for home use quite acceptable. The maximum cross-section is up to 40 mm. The thickness of the processed metal is 5-6 mm.
- Tapered step drill. It is more convenient to use, since each step is formed through a smooth spiral transition. When drilling, this makes it easy to track the actual diameter of the hole. With its help you can drill a circle up to 40 mm in diameter on metal up to 6 mm thick.
- Bimetallic crowns - suitable for preparing holes up to 109 mm in steel products up to 5 mm thick. When working, it is strongly recommended to use specialized lubricating and cooling compounds, which will ensure maximum service life of the cutting tool. An adapter is also required to install the device on an electric drill. On average, using a bimetallic crown, you can drill 5-20 openings - depending on its quality, which, accordingly, is reflected in the cost.
How can you drill a large hole without extra costs?
For this method, you will need a small cross-section drill (5-6 mm is enough), as well as a milling cutter or a used grinding wheel (corresponding to or slightly smaller than the diameter of the hole) for an angle grinder. The option is more labor-intensive, so it takes much more time.
On a metal blank, 2 circles are drawn with a pencil:
- 1 - for the future hole.
- 2 - depends on the cross-section of the drill, that is, when using a 6 mm tool, the diameter of the intended circle will be 6 mm smaller than the previous one.
Along the 2nd circle it is necessary to mark 2 places in opposite places and drill holes with a 6 mm drill. From the resulting openings along the intended line you need to retreat approximately 3 mm and again mark the places for drilling. Holes are drilled along the entire circumference. If necessary, the remaining sections can be cut with a chisel.
The hole will be jagged, so it needs to be bored out. This can be done with an electric drill with a cutter, but it is much more convenient with a grinder using grinding abrasive wheels of a suitable diameter. Using a grinder, you can quickly and evenly bore a hole to the required diameter.
Therefore, you should not throw away used abrasive wheels for an angle grinder with a diameter of even less than 45 mm - they can always be useful on the farm.
Drilling through holes in metal workpieces is done with various tools using special techniques. To many specialists when performing engineering work you have to drill holes in metal structures often. These objects have high elasticity, which forces the use of special cutting devices when drilling.
Types of drills and devices for drilling in metal
Necessary equipment for drilling metal products - electrical and hand drills, and drilling machines. Working part such devices - a drill of different shapes:
- spiral;
- screw;
- crown-shaped;
- conical;
- flat;
- cannon;
- rifle;
- centering;
- stepped.
Each drill is individually marked, where the tip indicates the cross-sectional diameter and the type of alloy from which it is made. To drill a hole of the required diameter, you need a drill a few tenths of a millimeter narrower.
Drills are also classified by length:
- short;
- elongated;
- long.
Drilling in some materials may require a specially sharpened diamond-tipped drill bit. Twist drills may not be able to handle products made from thin sheet alloys. In some cases for drilling deep holes the product must be fixed in a vice, stops, jigs, corners with fasteners. This is done for safety reasons and to obtain high quality holes.
Modes for drilling holes in metal products
For drilling through holes in metal products Preliminary preparation for the process is extremely important. The drill must be correctly secured and guided in the tool. You need to adjust the rotation speed and other parameters. For overly durable products it is recommended low speed rotation of the drill. An indicator of correct drilling should be uniform, long chips.
Types of holes and methods for drilling them
Some manufacturing jobs often require the following types of holes in metal workpieces:
- Through. They completely pierce metal workpieces. It is important to protect the surface of the machine from accidental exit of the drill beyond the workpiece in order to avoid damage to the drill and the occurrence of burrs on the blank. Workbenches with holes are ideal for such types of work, where it is possible to place them under the workpiece. wooden spacer. Holes in thin blanks are drilled with flat drills, because a twist drill can noticeably destroy the edges of the product.
- Deaf. They are carried out to the required depth without penetrating the product right through. In this case, an important point is measuring the depth, which can be conveniently done by limiting the length of the drill by the stop of the sleeve or the drill chuck with a locking stop. Professional machines equipped automatic systems feed to the specified penetration size, which allows you to fix the depth of the drill.
- Deep. This type of hole includes those drills whose length is five times the diameter. When drilling deep holes, it is necessary to periodically remove the resulting chips using additional lubricants. Often it is necessary to enforce measures to cool the drill and the workpiece itself, the temperature of which rapidly rises to too high levels as a result of friction. This applies to workpieces made of high-strength alloys. For deep holes, twist drills are used.
- Wide diameter. Drilling large-diameter holes in products of large proportions is a very responsible and labor-intensive process. For such holes, conical, crown-shaped or stepped drills are used. Specialists carry out drilling at low tool speeds, trying to ensure the safety of the edges of the workpiece.
- Complex shape. Sometimes it is necessary to drill through or blind holes in workpieces of different densities under internal thread. The technology has to be divided into two actions: preliminary preparation platforms and the drilling itself.
- Half-hearted. Half blanks are drilled, filling the cavities with wood. Stepped holes can be obtained using one of two techniques: reaming (passing a drill of a smaller diameter to the entire depth of the workpiece, followed by reaming with drills larger diameter) and reducing the diameter (by drilling a hole of a larger diameter to the required depth and then replacing a drill with a smaller diameter). As a result, the hole is clearly centered.
Safety when drilling holes in metal workpieces
When drilling holes in metal workpieces, you should be very careful to avoid rapid destruction of the drill. Compliance simple rules when drilling, it will ensure safety and guarantee a high-quality product upon completion of the work:
- On the eve of drilling, you must carefully check the fixation of all fastening devices on the machine.
- You can start work in special clothing to prevent any elements from getting under the moving parts of the machine. Protect your eyes from metal shavings with special glasses.
- When the drill tip enters a metal workpiece, it should already be rotating at low speeds to avoid dulling.
- Drill out drilled hole should be done gradually, reducing the speed, but not stopping completely.
- When the drill tip does not penetrate into the workpiece, you will have to check the strength of the metal. When running a file over the surface, it is possible to determine the degree of strength. If there is no roughness left on the alloy, you need to choose a drill with a diamond tip or from a harder material, and drill at low speeds.
- Drills of small diameter, which are difficult to fix in the chuck, are recommended to be wrapped around the tail with brass wire to increase the diameter of the girth.
- If you are working with a polished workpiece, you can put a felt washer on the base of the drill to avoid damage when it comes into contact with the drill chuck.
- To fix metal workpieces made of polished or chrome-plated steel, fabric or leather spacers are used.
- When drilling deep holes, a small piece of compressed foam placed on the drill will ensure that small metal shavings are blown away. Also, foam plastic will make it possible to deepen the drill to the required level when producing blind holes.
The power of electric drills must be taken into account when drilling holes in metal workpieces of varying hardness. Manufacturers of power tools label devices indicating specifications on their body. For drills different power Drills of the appropriate diameter are assumed.
You can entrust any tasks, including drilling, to the specialists of the Proflazermet company. We will determine the required hole diameter and select suitable tool, which we have big choice. In the end you will get perfect solution in short time.