Metal processing is carried out not only in industrial conditions. When executing 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 to work 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 is to remove a thin layer of material due to simultaneous translational and rotational movement.

The main condition for high-quality and safe (for the tool) processing is keeping the chuck axis in a fixed position. Using a machine is easy to maintain straightness, which is not the case when working with hand tools.

If you are not confident in the steadiness of your hands (this is a normal situation for ordinary person), for drilling at right angles, mechanical assistants (conductors) are required.

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-held electric drills. Power-driven tools are not suitable for working with metal, especially when it comes to precision.

1. Drilling jig. Made in the form of a housing, convenient to hold, inside of which guide bushings for drills are located various diameters.


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 slide off the cylindrical surface.



2. Guide for drill (manual). Support device, in which the instrument is fixed by the neck


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.

Subject to availability rotary 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.

3. Drill stand (semi-stationary). In fact it is an inexpensive alternative drilling machine.

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 of a conventional drill for a hand-held electric drill 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. Large quantity 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 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.

All photos from the article

If you need to make a large diameter hole in a tree, you will have to use special devices, each of which has its own characteristics. We'll look at everything possible options and we will tell you about their main advantages and disadvantages so that you can choose best option in accordance with the specifics of work in a given situation.

Criteria for choosing a quality option

Below we will look at the main types of devices, but for now we will outline the criteria that any option must meet, regardless of its modification:

Reliable manufacturing material	Of course, it is unlikely to be possible to determine this criterion by eye, so it is best to ask the seller for a quality certificate for the product. Unreliable counterfeit versions from China most often do not have any documents.
High quality performance	Carefully examine the product: the surface must be smooth without flaws or defects, the cutting part must be carefully sharpened. If you purchase a long wood drill, check whether it is level; this can be done by eye or by rolling it along flat surface– any violations are immediately visible on it.
Good packaging	Low-quality fakes are most often packaged haphazardly, moreover, there are mistakes in the words. No well-known brand will allow itself unsightly packaging, remember this.
Price	Price is also an indicator of quality; as a rule, the most budget options do not last long, especially when it comes to large-sized drills and fixtures. After all, they are very exposed high loads in the process of work.

Advice! To be guaranteed to purchase a quality product, be it , you need to contact official representatives of a particular brand or buy products from well-known stores that care about their reputation and do not sell cheap fakes.

Types of products and their features

Let's consider what options can be found in our trading network and how they differ from each other.

Feather drills

The most common and budget option, which are quite convenient to work even for inexperienced craftsmen. And you can also master this simple process with your own hands.

Let's look at the main advantages of this solution:

• The diameter range varies from 10 to 60 mm.
• The work is done quite quickly, but the quality of the hole is low, to achieve perfect result It's unlikely to work.
• The maximum drilling depth is approximately 150 mm.
• Products are sold either in sets of 5-6 pieces or individually, so you decide which option is right for you.
• If necessary, you can buy an extension that clamps the drill and increases its length by 300 mm.

Large sizes are usually sold individually, small sizes are usually sold in sets.

You can't help but touch on this interesting option as adjustable feather drill, this type of product can make holes with a diameter of 22 to 76 mm. The work is carried out at low speeds using fairly powerful power tools.

Drilling large holes is not a problem if you choose the right tool. For example, such work may be necessary to secure a channel or metal corner. The easiest way is to use an electric drill, but getting a hole with a diameter of, for example, 15 mm requires a lot of effort. To drill a large diameter hole in metal, special devices and core drilling technology are used.

Features of creation

When drilling, it must be taken into account that the crown or stepped cone nozzle must be selected so that it has a smaller diameter than the hole being created.

When using various instruments it is also necessary to take into account their characteristics. For example, when drilling with conical products, smooth edges are obtained.

Drill accessories

There are several accessories for drills that can make the process easier and make big hole flat:

• Drilling jig. Such a device is a housing in which there are several guide bushings for drills of different diameters. The material used to create the bushings is harder than drill bits, so you don't have to worry about the tool moving to the side while drilling and widening the hole.
• Drill guide. This product allows you to fix the tool in such a way that it does not deviate to the side during drilling. If such a product is not available, the tool may move to the side, resulting in an uneven edge. It can also be mounted at an angle. But when drilling metal products this is usually not required.
• Drill stand. A DIY product like this can be an inexpensive replacement for a drilling machine, as it allows you to carry out work more comfortably. When using a stand, a fixed tool moves along the bar using a lever. In this case, displacement is completely eliminated, since the workpiece being drilled is securely held due to the presence of a clamp.

Using these products, you can greatly facilitate the process of drilling metal products.

Feature of deep holes

To drill a deep hole in metal, it is best to use lathe. During this process be sure to cool down. In this case, the chips must be forcibly removed. Periodically, the tool is removed from the workpiece to remove chips.

When working without specialized devices Do not recess the nozzle more than 2/3 of its length. Water must be used for cooling during operation. If the work is done in several approaches, changing the angle is not allowed.

Features of large diameter holes

This procedure is more complex than deep drilling. Cutting work is carried out either using a crown or using a cone drill. Crowns for metal are similar to products for concrete and drywall. The only difference is in the material used to create the cutting edge.

Drilling can also be carried out with standard products in several stages. To do this, first use a small diameter nozzle. Then a larger tool is selected.

Most in a convenient way is the use of cone drills. Such devices allow you to drill a large hole in one go. To do this, the tool is simply recessed into the material.

Hassle-free drilling

During work, you can use a small section nozzle, as well as a used grinding wheel for an angle grinder. It is important to remember that it should have a smaller diameter than the hole being created.

Before carrying out work, a circle for the hole is marked on the workpiece, and the second circle will be smaller than the first by a distance equal to the diameter of the drill used. After this, 2 holes are marked in opposite places of the circle. It is necessary to retreat 3 mm from them and mark the places for drilling. Thus, drilling occurs along the entire drawn circle. If additional work is necessary, some areas will have to be processed with a chisel. This will create jagged edges that will then need to be filed down. It is important to ensure that during work the circumference does not increase, i.e. do not expand the planned diameter.

Cone drill

The described types of drills are made from tool steel. The shanks of such products can be hexagonal or cylindrical. Cutting edge removes all burrs, so the edge is smooth. The end of the drill head has a sharpened point that allows pre-drilling of the material.

Using these products you can:

• create cuts with a diameter of up to 30 mm;
• forget about jagged edges;
• carry out boring of various diameters without changing the nozzle.

Thanks to step drills You can create cuts of various diameters in sheet steel up to 4 mm thick. Unlike a simple cone drill, when using such products, the drilled diameter is fixed.

The disadvantages include:

• the need to use tools with low speeds and high torque;
• sensitivity even to small distortions.

Despite the indicated disadvantages, this attachment allows you to conveniently work with metal plates, quickly drilling circles of the desired diameter.

Metal crown

Metal processing is complex process, therefore such work is usually carried out using specialized equipment. To do work in living conditions, you can use core drills.

Such products allow you to make the edges round and centered. In this case, a standard drill is used for drilling. The products consist of several parts:

• crown;
• centering attachment;
• product shank;
• screws that are necessary for fastening.

When using a core drill, the speed of work increases up to 10 times. Another advantage is the ability to accurately drill in the range from 1.2 to 15 cm.

In this case, there is no need to perform alignment during drilling. It is also worth noting that such drills have higher wear resistance compared to twist drills.

Before starting work, a centering drill is installed in the center of the circle, after which drilling is carried out. After this, the drill is retracted and the work is carried out with a crown.

Hole press

One of the common methods is punching using a special press. It happens like this:

1. First, the workpiece is placed on the press table and grabbed by several clamps.
2. The metal is then moved under the punching tool. At this stage, additional fastening of the material occurs using a clamping ring.
3. At the last stage, penetration occurs using a punch.

The revolver can have several attachments of different diameters, which allows you to quickly create holes of different diameters. Such equipment is usually not used for working with metal in domestic conditions.

If you plan to do the work at home, you should choose a universal tool. This will allow you to easily process metal without worrying about purchasing additional parts. The video presented will introduce you in detail to the technology of the process.

Despite the fact that cutting internal threads is not a complex technological operation, there are some features of preparation for this procedure. Thus, it is necessary to accurately determine the dimensions of the preparation hole for cutting threads, and also select the right tool, for which special tables of drill diameters for threads are used. For each type of thread, it is necessary to use the appropriate tool and calculate the diameter of the preparation hole.

Types and parameters of thread

The parameters by which threads are divided into various types, are:

• units of diameter (metric, inch, etc.);
• number of thread starts (one-, two- or three-thread);
• the shape in which the profile elements are made (triangular, rectangular, round, trapezoidal);
• direction of rise of turns (right or left);
• location on the product (external or internal);
• surface shape (cylindrical or conical);
• purpose (fastening, fastening and sealing, chassis).

Depending on the above parameters, the following types of thread are distinguished:

• cylindrical, which is designated by the letters MJ;
• metric and conical, designated M and MK respectively;
• pipe, designated by the letters G and R;
• with a round profile, named after Edison and marked with the letter E;
• trapezoidal, designated Tr;
• round, used for installation of sanitary fittings, – Kr;
• thrust and thrust reinforced, marked as S and S45, respectively;
• inch thread, which can also be cylindrical and conical - BSW, UTS, NPT;
• used to connect pipes installed in oil wells.

Application of the tap

Before you start threading, you need to determine the diameter of the preparation hole and drill it. To facilitate this task, the corresponding GOST was developed, which contains tables that allow you to accurately determine the diameter of the threaded hole. This information makes it easy to select the drill size.

To cut metric threads on the inner walls of a hole made with a drill, a tap is used - a screw-shaped tool with cutting grooves, made in the form of a rod, which can have a cylindrical or conical shape. On its side surface there are special grooves located along its axis and dividing the working part into separate segments, which are called combs. The sharp edges of the combs are precisely the working surfaces of the tap.

In order for the turns of the internal thread to be clean and neat, and its geometric parameters to correspond to the required values, it must be cut gradually, by phased withdrawal thin layers of metal from the treated surface. That is why for this purpose they use either taps, the working part of which is divided along the length into sections with different geometric parameters, or sets of such tools. Single taps, the working part of which has the same geometric parameters along its entire length, are needed in cases where it is necessary to restore the parameters of an existing thread.

The minimum set with which you can sufficiently perform machining of threaded holes is a set consisting of two taps - rough and finishing. The first one cuts holes from the walls for cutting metric threads thin layer metal and forms a shallow groove on them, the second not only deepens the formed groove, but also cleans it.

Combination two-pass taps or sets consisting of two tools are used for tapping small diameter holes (up to 3 mm). For processing holes for metric thread larger diameter you must use a combination three-pass tool or a set of three taps.

Used for manipulating the tap special device- collar. The main parameter of such devices, which can have different designs, is the size of the mounting hole, which must exactly match the size of the tool shank.

When using a set of three taps, differing both in their design and geometric parameters, the sequence of their use should be strictly observed. They can be distinguished from each other both by special marks applied to the shanks and by design features.

1. The tap, with which the hole for cutting a metric thread is processed first, has the minimum diameter among all the tools in the set and cutting teeth, upper part which are heavily cropped.
2. The second tap has a shorter fence and longer combs. Its working diameter is intermediate between the diameters of the other tools in the set.
3. The third tap, with which the hole for cutting metric threads is processed last, is characterized by full ridges of cutting teeth and a diameter that must exactly match the size of the thread being formed.

Taps are used primarily for cutting metric threads. Much less often than metric ones, taps designed for processing the internal walls of pipes are used. In accordance with their purpose, they are called pipe, and they can be distinguished by the letter G present in their markings.

Internal thread cutting technology

As mentioned above, before starting work, you need to drill a hole, the diameter of which must exactly fit a thread of a certain size. It should be borne in mind: if the diameters of the holes intended for cutting metric threads are chosen incorrectly, this can lead not only to poor quality execution, but also to breakage of the tap.

Considering the fact that the tap, when forming threaded grooves, not only cuts the metal, but also pushes it, the diameter of the drill for making threads should be slightly smaller than its nominal diameter. For example, a drill for making M3 threads should have a diameter of 2.5 mm, for M4 - 3.3 mm, for M5 you should choose a drill with a diameter of 4.2 mm, for M6 threads - 5 mm, M8 - 6.7 mm, M10 - 8.5 mm, and for M12 - 10.2.

Table 1. Main diameters of holes for metric threads

All diameters of drills for GOST threads are given in special tables. Such tables indicate the diameters of drills for making threads with both standard and reduced pitches, it should be borne in mind that holes are drilled for these purposes different diameters. In addition, if threads are cut in products made of brittle metals (such as cast iron), the diameter of the thread drill obtained from the table must be reduced by one tenth of a millimeter.

You can familiarize yourself with the provisions of GOST regulating the cutting of metric threads by downloading the document in pdf format follow the link below.

The diameters of drills for metric threads can be calculated independently. From the diameter of the thread that needs to be cut, it is necessary to subtract the value of its pitch. The thread pitch itself, the size of which is used when performing such calculations, can be found out from special correspondence tables. In order to determine what diameter the hole needs to be made using a drill if a three-start tap is used for threading, you must use the following formula:

D o = D m x 0.8, Where:

D o- this is the diameter of the hole that must be made using a drill,

D m– the diameter of the tap that will be used to process the drilled element.