Extrusion of a hole in metal with a large diameter. How to make a hole in a pipe with your own hands. How to drill holes in large diameter metal

Hole drilling now large diameter in metal is not a serious problem... The main thing is to prepare well. Let's say you need to make a hole in a corner, channel or mortgage in order to strengthen building structure or hang a shelf, lamp or duct. That is, to do this not in a workshop or workshop, but directly at the place. The easiest way to drill in such conditions is to use an electric drill. But, imagine how much pressure you need to apply to drill a hole with a diameter of 16 or 20 mm? The question is not rhetorical - the effort will be about 40-50 kgf. This is not easy to achieve if the intended hole is located above the level of the driller's shoulders. Even 10 years ago, when such a problem arose, even professionals resorted to autogenous and, imagine only, to 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 convinced that core drilling is a rather expensive method, cost-effective only for industrial volumes. Is this statement true? Partly. Today, you can choose several options for tools and equipment for drilling a hole in large diameter metal without reaming. In this case, the cost per hole will be justified even when drilling only a few holes.

Consider what tool options the market offers for drilling large-diameter through holes in metal... For comparison, we take a diameter of 51 mm.

First is bimetallic crowns... Samples from the cheapest are presented to choose from, which are immediately sold in sets and cannot be accepted by us in this review for the reason that their purpose is to drill wood, and if they do succeed in drilling a sheet of metal, then 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 they are 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, cobalt there may not be at all. Twice as expensive bits of more decent quality, really allowing 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 with a thickness of 5 mm. At the same time, the use of any lubricating-cooling composition ensures the achievement of top bar this range. At the third stage there are bimetallic crowns of world famous brands, which are twice as expensive, can be equipped with special devices for a quick change in the drill, but in terms of resource they do not greatly or do not exceed the average price level.

Drilling large holes in steel sheets with a thickness of more than 5-6 mm for bimetallic crowns it is very difficult, although sometimes you can hear a different opinion. It is based on data on the total 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 to drill a 30 mm sheet or beam in this way. The fact is that a bimetallic crown is devoid of a chip-evacuation groove, and as soon as the thickness of the drilled metal becomes greater than the height of the tooth of the crown, problems with chip evacuation begin. In addition, the body of the bimetallic bit is not quite cylindrical, this causes jamming in metal of solid thickness.

In contrast to bimetallic bits, they provide more accurate drilling. The body of the carbide hole saw is chiselled, 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 attachment, we will analyze only the cutting part. The most expensive part of the crown is the carbide teeth. The quality of the material greatly affects 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 groove, and they will not be able to drill metal thicker than the height of their tooth. The price of such bits is two to three times higher than that of bimetallic bits, depending on the design of their case, they can be designed or. Since these are professional samples, at present their counterfeits are not widespread, and almost all samples found on the market are of acceptable quality, but excellent quality should be chosen from manufacturers specializing in these products.

Thicker metal can be drilled. In these bits, every second or, as a rule, one of three successive carbide teeth is sharpened in a different way. This ensures a soft cut, no vibration, less stress on the cutting edges and, as a result, an increase in the life of the bit. In such crowns, there is a short or long chip-removal groove, almost to 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. It is this version of the tool for drilling a hole in metal of large diameter that is the most progressive, providing better performance and quality. The price of such crowns is 20-30% higher than that of thin-walled and in absolute terms 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, considering builds a golden mean.

The 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 an electric drill can also be used. With the above-mentioned machine, investments will amount to 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... A large load causes a high cost of investment in equipment, and together with a crown it will amount to about 56,000 rubles, or, option with magnetic drill stand and a separately purchased drill about 50,000. To drill such holes with a drill from your hands is not only difficult, but also dangerous.

Drilling with a hand electric drill in metal up to 5 mm thick holes of large diameter is not difficult when using both bimetallic and carbide bits. The choice of the tool is carried out depending on the required accuracy. When drilling holes with a bimetallic bit, the ovality of holes and an increase in diameter from the desired one can reach 4% or in absolute terms - 2 - 3 mm. When drilling with a carbide bit, only 0.6 - 1 mm. In addition, all of the carbide bits presented in the review, and almost all of the metal bits on the market, drill stainless steel as well.

Despite the fact that tapping is not a complex technological operation, there are some peculiarities of preparation for this procedure. So, it is necessary to accurately determine the dimensions of the preparatory hole for threading, as well as to choose the right tool, for which special tables of diameters of drills for thread are used. For each type of thread, the appropriate tool must be used and the diameter of the preparation hole must be calculated.

Varieties and parameters of thread

The parameters by which the thread is divided into different types are:

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

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

• cylindrical, which is designated by the letters MJ;
• metric and conical, denoted respectively M and MK;
• pipe, for which the letters G and R are used;
• with a round profile, named after Edison and marked with the letter E;
• trapezoidal, denoted by Tr;
• round, used for the installation of plumbing fixtures - Kr;
• resistant and resistant 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.

Tap application

Before proceeding with threading, the diameter of the preparation hole must be determined and drilled. To facilitate this task, the corresponding GOST was developed, which contains tables that allow you to accurately determine the diameter of the hole for the thread. This information makes it easy to select the drill size.

To cut a metric type thread 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 lateral 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 dies are precisely the working surfaces of the tap.

To make the threads of the internal thread clean and neat, and its geometric parameters correspond to the required values, it must be cut gradually, by gradually removing thin layers of metal from the surface to be treated. That is why, for this purpose, either taps are used, 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 the help of which it is possible to perform sufficiently high-quality machining of the holes for the thread, is a set consisting of two taps - roughing and finishing. The first cuts off a thin layer of metal from the walls of the hole for cutting metric threads and forms a shallow groove on them, the second not only deepens the formed groove, but also cleans it.

Combined two-way taps or sets of two tools are used for tapping small holes (up to 3 mm). For machining holes for metric thread with a larger diameter, a combination 3-pass tool or a set of 3 taps must be used.

To manipulate the tap, a special device is used - a knob. The main parameter of such devices, which can have a different design, is the size of the bore, which must exactly match the size of the tool shank.

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

1. The tap, with which the hole for tapping metric threads is first processed, has the smallest diameter among all the tools in the set and cutting teeth, the upper part of which is heavily cut.
2. The second tap has a shorter nose and longer flanges. Its working diameter is intermediate between the diameters of the rest of the tools from the set.
3. The third tap, with which the metric hole is machined last, is characterized by full ridges of the cutting teeth and a diameter that must exactly match the size of the thread to be formed.

Taps are mainly used for tapping metric threads. Significantly less often than metric taps are used for processing the inner walls of pipes. In accordance with their purpose, they are called pipe, and they can be distinguished by the letter G, which is present in their marking.

Internal threading technology

As mentioned above, before starting work, you need to drill a hole, the diameter of which must exactly fit the 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 its poor quality, but also to the breakage of the tap.

Considering the fact that the tap, while forming the threaded grooves, not only cuts the metal, but also pushes it, the diameter of the drill for making the thread should be slightly smaller than its nominal diameter... For example, a drill for threading M3 should have a diameter of 2.5 mm, for M4 - 3.3 mm, for M5, 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

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

You can familiarize yourself with the GOST provisions governing the cutting of metric threads by downloading the pdf document from the link below.

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

D o = D m x 0.8, where:

Before Is the diameter of the hole to be made with a drill,

D m- the diameter of the tap, which will be used to process the drilled element.

Work on drilling holes in metal, depending on the type of holes and the properties of the metal, can be performed different tools and using various techniques. We would like to tell you about the methods of drilling, tools, as well as safety precautions when performing these works.

Drilling holes in metal may be needed for repairs engineering systems, household appliances, a car, the creation of structures from sheet and profile steel, the design of crafts from aluminum and copper, in the manufacture of boards for radio equipment and in many other cases. It is important to understand what tool is needed for each type of work, so that the holes are of the right diameter and in a strictly designated place, and what safety measures will help to avoid injuries.

Tools, fixtures, drills

The main tools for drilling are handheld and electric drills and, if possible, drilling machines. The working body of these mechanisms - a drill - can have a different shape.

There are drills:

• spiral (most common);
• screw;
• crowns;
• conical;
• feathers, etc.

Drill production of various designs standardized by numerous GOSTs. Drills up to Ø 2 mm are not marked, up to Ø 3 mm - the shank indicates the section and steel grade, larger diameters may contain Additional information... To obtain a hole of a certain diameter, you need to take a drill a few tenths of a millimeter smaller. The better the drill is sharpened, the smaller the difference between these diameters.

Drills differ not only in diameter, but also in length - they are produced short, elongated and long. Important information is the ultimate hardness of the metal being processed. The drill shank can be cylindrical or tapered, which should be borne in mind when choosing a drill chuck or adapter sleeve.

1. Drill with cylindrical shank. 2. Drill with taper shank. 3. Drill with a sword for carving. 4. Center drill. 5. Drill with two diameters. 6. Center drill. 7. Conical drill. 8. Conical multistage drill

Some work and materials require special sharpening. The harder the metal being processed, the sharper the edge should be. For thin sheet metal, a conventional twist drill may not work; you will need a tool with a special sharpening. Detailed recommendations for different types drills and processed metals (thickness, hardness, hole type) are quite extensive, and we will not consider them in this article.

Various types of drill sharpening. 1. For rigid steel. 2. For of stainless steel... 3. For copper and copper alloys. 4. For aluminum and aluminum alloys. 5. For cast iron. 6. Bakelite

1. Standard sharpening. 2. Free sharpening. 3. Diluted sharpening. 4. Heavy sharpening. 5. Separate sharpening

To fix the parts before drilling, vices, stops, conductors, corners, clamps with bolts and other devices are used. This is not only a safety requirement, but in fact it is more convenient and the holes are of better quality.

For chamfering and processing of the channel surface, a cylindrical or conical countersink is used, and a hammer and a center punch are used to mark a point for drilling and so that the drill “does not jump off”.

Advice! The best drills are still considered to be produced in the USSR - the exact adherence to GOST on the geometry and composition of the metal. The German Ruko with titanium coating are also good, as well as drills from Bosch - a proven quality. Good feedback about Haisser products - powerful, as a rule, large diameter. The Zubr drills, especially the Cobalt series, have shown themselves worthy.

Drilling modes

It is very important to secure and guide the drill correctly and to select the cutting mode.

When making holes in metal by drilling important factors are the number of revolutions of the drill and the feed force applied to the drill, directed along its axis, providing the drill depth at one revolution (mm / rev). When working with various metals and drills, various cutting conditions are recommended, and the harder the metal being processed and the larger the drill diameter, the lower the recommended cutting speed. The indicator of the correct mode is beautiful, long chips.

Use the tables to choose the right mode and not dull the drill prematurely.

Table 2. Correction factors

Table 3. RPM and feed for different drill diameters and drilling in carbon steel

Types of holes in metal and how to drill them

Hole types:

• deaf;
• end-to-end;
• half (incomplete);
• deep;
• large diameter;
• for an internal thread.

Thread holes require the definition of diameters with tolerances set in GOST 16093-2004. For common hardware, the calculation is shown in table 5.

Table 5. Ratio of metric and inch threads, as well as selection of hole size for drilling

Through holes

Through holes penetrate the workpiece completely, forming a passage in it. A feature of the process is the protection of the surface of the workbench or table top from the drill going out of the workpiece, which can damage the drill itself, as well as provide the workpiece with a "burr" - a guard. To avoid this, use the following methods:

• use a workbench with a hole;
• put a gasket made of wood or "sandwich" - wood + metal + wood under the part;
• a metal bar with a hole for the free passage of the drill is placed under the part;
• reduce the feed rate in the last step.

The latter method is mandatory when drilling holes "in place" so as not to damage closely spaced surfaces or parts.

Holes in thin sheet metal are cut with nib drills because the twist drill will damage the edges of the workpiece.

Blind holes

Such holes are made to a certain depth and do not penetrate the workpiece through and through. There are two ways to measure depth:

• limiting the length of the drill with a sleeve stop;
• limiting the length of the drill with a chuck with an adjustable stop;
• using a ruler fixed on the machine;
• a combination of ways.

Some machines are equipped with an automatic feed to a predetermined depth, after which the mechanism stops. During the drilling process, it may be necessary to stop work several times to remove the chips.

Complex holes

Holes located on the edge of the workpiece (half) can be made by connecting two workpieces or the workpiece and the gasket with the edges and clamping them with a vice and drilling a full hole. The gasket must be made of the same material as the workpiece to be machined, otherwise the drill will "go" towards the least resistance.

A through hole in the corner (profile metal rolling) is performed by fixing the workpiece in a vice and using a wooden gasket.

It is more difficult to drill a cylindrical workpiece tangentially. The process is divided into two operations: preparation of the site perpendicular to the hole (milling, countersinking) and the actual drilling. Drilling holes in angled surfaces also begins with site preparation, after which a wooden spacer is inserted between the planes, forming a triangle, and a hole is drilled through the corner.

The hollow parts are drilled by filling the cavity with a wood cork.

Shoulder holes are produced using two techniques:

1. Reaming. The hole is drilled to the full depth with a drill of the smallest diameter, after which it is reamed to a given depth with drills with diameters from smaller to larger. The advantage of the method is a well-centered hole.
2. Reducing the diameter. A hole of the maximum diameter is drilled to a given depth, then the drills are changed with a sequential decrease in the diameter and deepening of the hole. This method makes it easier to control the depth of each step.

1. Reaming the hole. 2. Reducing the diameter

Large holes, circular drilling

Obtaining large-diameter holes in massive workpieces, up to 5-6 mm thick, is a laborious and costly business. Relatively small diameters - up to 30 mm (maximum 40 mm) can be obtained using taper, or better step-taper drills. For holes with a larger diameter (up to 100 mm), you will need hollow bimetallic or carbide-tipped bits with a center drill. Moreover, the masters traditionally recommend Bosch in this case, especially on hard metal for example steel.

This hole drilling is less energy intensive, but can be more costly. In addition to drills, the power of the drill and the ability to work at the lowest speeds are important. Moreover, the thicker the metal, the more you will want to make a hole on the machine, and if a large number holes in a sheet with a thickness of more than 12 mm, it is better to immediately look for such an opportunity.

In a thin-sheet blank, a large-diameter hole is obtained with the help of narrow-toothed crowns or a milling cutter fixed on a "grinder", but the edges in the latter case leave much to be desired.

Deep holes, coolant

Sometimes a deep hole is required. In theory, this is a hole that is five times its diameter. In practice, deep drilling is called drilling, requiring periodic forced removal of chips and the use of coolants (cutting fluids).

In drilling, coolant is needed primarily to reduce the temperature of the drill and workpiece, which are heated by friction. Therefore, when making holes in copper, which has a high thermal conductivity and is itself capable of removing heat, the coolant can be omitted. Cast iron can be drilled relatively easily and without lubrication (except for high-strength ones).

In production, industrial oils, synthetic emulsions, emulsols and some hydrocarbons are used as coolant. In home workshops, you can use:

• technical vaseline, castor oil - for mild steels;
• laundry soap- for aluminum alloys such as D16T;
• a mixture of kerosene with castor oil - for duralumin;
• soapy water - for aluminum;
• turpentine diluted with alcohol - for silumin.

The universal refrigerated liquid can be prepared independently. To do this, you need to dissolve 200 g of soap in a bucket of water, add 5 tablespoons of engine oil, you can waste it, and boil the solution until a soapy homogeneous emulsion is obtained. Some craftsmen use lard to reduce friction.

Deep holes can be made with solid and circular drilling, and in the latter case, the central rod, formed by the rotation of the crown, is not broken out entirely, but in parts, weakening it with additional small-diameter holes.

Solid drilling is performed in a well-fixed workpiece with a twist drill, into the channels of which coolant is supplied. Periodically, without stopping the rotation of the drill, you need to remove it and clean the cavity from chips. Work with a twist drill is performed in stages: first, take a short one and drill a hole, which is then buried with a drill of the appropriate size. If the hole depth is significant, it is advisable to use jig bushings.

With regular drilling of deep holes, it is recommended to purchase a special machine with automatic feeding Coolant to drill and accurate centering.

Drilling by marking, template and jig

You can drill holes according to the made markings or without them - using a template or a jig.

Marking is done with a center punch. With a hammer blow, a place is marked for the tip of the drill. With a felt-tip pen, you can also mark the place, but the hole is also needed so that the tip does not move from the intended point. The work is done in two stages: pre-drilling, hole inspection, final drilling. If the drill has "gone" from the intended center, notches (grooves) are made with a narrow chisel, guiding the point to the specified place.

To determine the center of a cylindrical blank, a square piece of sheet metal is used, bent at 90 ° so that the height of one shoulder is approximately one radius. Applying corner with different sides workpiece, run a pencil along the edge. As a result, you have an area around the center. You can find the center by the theorem - the intersection of perpendiculars from two chords.

The template is needed when performing a series of similar parts with several holes. It is convenient to use it for a pack of thin-sheet blanks connected by a clamp. In this way, several drilled workpieces can be obtained at the same time. Instead of a template, a drawing or diagram is sometimes used, for example, in the manufacture of parts for radio equipment.

The conductor is used when the accuracy of maintaining the distances between the holes and the strict perpendicularity of the channel are very important. When drilling deep holes or when working with thin-walled tubes, in addition to the conductor, guides can be used to fix the position of the drill relative to the metal surface.

When working with a power tool, it is important to remember about human safety and avoid premature wear of the tool and possible marriage. In this regard, we have collected some useful tips:

1. Before work, you need to check the fastenings of all elements.
2. When working on a machine or with an electric drill, clothes should not contain elements that can get under the influence of rotating parts. Protect your eyes from shavings with goggles.
3. The drill, when approaching the surface of the metal, must already rotate, otherwise it will quickly become dull.
4. It is necessary to remove the drill from the hole without turning off the drill, reducing the speed if possible.
5. If the drill does not go deep into the metal, then its hardness is lower than that of the workpiece. Increased hardness in steel can be detected by drawing a file over the sample - the absence of traces indicates increased hardness. In this case, the drill must be selected from carbide with additives and work at low speeds with a small feed.
6. If the drill small diameter does not fit well in the chuck, wind a few turns of brass wire around its shank, increasing the diameter for gripping.
7. If the surface of the workpiece is polished, place a felt washer over the drill to ensure that no scratches occur even when touching the drill chuck. When securing polished or chromed steel workpieces, use cloth or leather spacers.
8. When making deep holes, a rectangular piece of polystyrene, mounted on a drill, can serve as a gauge and, at the same time, rotate to blow off small chips.

Work on drilling holes in metal, depending on the type of holes and the properties of the metal, can be performed with different tools and using different techniques. We would like to tell you about the methods of drilling, tools, as well as safety precautions when performing these works.

Drilling holes in metal may be needed when repairing engineering systems, household appliances, a car, creating structures from sheet and profile steel, designing crafts from aluminum and copper, making boards for radio equipment, and in many other cases. It is important to understand what tool is needed for each type of work, so that the holes are of the right diameter and in a strictly designated place, and what safety measures will help to avoid injuries.

Tools, fixtures, drills

The main drilling tools are hand and power drills and, if possible, drilling machines. The working body of these mechanisms - a drill - can have a different shape.

There are drills:

• spiral (most common);
• screw;
• crowns;
• conical;
• feathers, etc.

The production of drills of various designs is standardized by numerous GOSTs. Drills up to Ø 2 mm are not marked, up to Ø 3 mm - the section and steel grade are indicated on the shank, larger diameters may contain additional information. To obtain a hole of a certain diameter, you need to take a drill a few tenths of a millimeter smaller. The better the drill is sharpened, the smaller the difference between these diameters.

Drills differ not only in diameter, but also in length - they are produced short, elongated and long. The limiting hardness of the processed metal is also important information. The drill shank can be cylindrical or tapered, which should be borne in mind when choosing a drill chuck or adapter sleeve.

1. Drill with cylindrical shank. 2. Drill with taper shank. 3. Drill with a sword for carving. 4. Center drill. 5. Drill with two diameters. 6. Center drill. 7. Conical drill. 8. Conical multistage drill

Some work and materials require special sharpening. The harder the metal being processed, the sharper the edge should be. For thin sheet metal, a conventional twist drill may not work; you will need a tool with a special sharpening. Detailed recommendations for various types of drills and work metals (thickness, hardness, hole type) are quite extensive, and we will not consider them in this article.

Various types of drill sharpening. 1. For rigid steel. 2. For stainless steel. 3. For copper and copper alloys. 4. For aluminum and aluminum alloys. 5. For cast iron. 6. Bakelite

1. Standard sharpening. 2. Free sharpening. 3. Diluted sharpening. 4. Heavy sharpening. 5. Separate sharpening

To fix the parts before drilling, vices, stops, conductors, corners, clamps with bolts and other devices are used. This is not only a safety requirement, but in fact it is more convenient and the holes are of better quality.

For chamfering and processing of the channel surface, a cylindrical or conical countersink is used, and a hammer and a center punch are used to mark a point for drilling and so that the drill “does not jump off”.

Advice! The best drills are still considered to be produced in the USSR - the exact adherence to GOST on the geometry and composition of the metal. The German Ruko with titanium coating are also good, as well as drills from Bosch - a proven quality. Good reviews for Haisser products - powerful, usually large diameter. The Zubr drills, especially the Cobalt series, have shown themselves worthy.

Drilling modes

It is very important to secure and guide the drill correctly and to select the cutting mode.

When making holes in metal by drilling, important factors are the number of revolutions of the drill and the feed force applied to the drill, directed along its axis, ensuring the penetration of the drill with one revolution (mm / rev). When working with different metals and drills, different cutting conditions are recommended, and the harder the metal being processed and the larger the drill diameter, the lower the recommended cutting speed. The indicator of the correct mode is beautiful, long chips.

Use the tables to choose the right mode and not dull the drill prematurely.

Table 2. Correction factors

Table 3. RPM and feed for different drill diameters and drilling in carbon steel

Types of holes in metal and how to drill them

Hole types:

• deaf;
• end-to-end;
• half (incomplete);
• deep;
• large diameter;
• for an internal thread.

Thread holes require the definition of diameters with tolerances set in GOST 16093-2004. For common hardware, the calculation is shown in table 5.

Table 5. Ratio of metric and inch threads, as well as selection of hole size for drilling

Through holes

Through holes penetrate the workpiece completely, forming a passage in it. A feature of the process is the protection of the surface of the workbench or table top from the drill going out of the workpiece, which can damage the drill itself, as well as provide the workpiece with a "burr" - a guard. To avoid this, use the following methods:

• use a workbench with a hole;
• put a gasket made of wood or "sandwich" - wood + metal + wood under the part;
• a metal bar with a hole for the free passage of the drill is placed under the part;
• reduce the feed rate in the last step.

The latter method is mandatory when drilling holes "in place" so as not to damage closely spaced surfaces or parts.

Holes in thin sheet metal are cut with nib drills because the twist drill will damage the edges of the workpiece.

Blind holes

Such holes are made to a certain depth and do not penetrate the workpiece through and through. There are two ways to measure depth:

• limiting the length of the drill with a sleeve stop;
• limiting the length of the drill with a chuck with an adjustable stop;
• using a ruler fixed on the machine;
• a combination of ways.

Some machines are equipped with an automatic feed to a predetermined depth, after which the mechanism stops. During the drilling process, it may be necessary to stop work several times to remove the chips.

Complex holes

Holes located on the edge of the workpiece (half) can be made by connecting two workpieces or the workpiece and the gasket with the edges and clamping them with a vice and drilling a full hole. The gasket must be made of the same material as the workpiece to be machined, otherwise the drill will "go" towards the least resistance.

A through hole in the corner (profile metal rolling) is performed by fixing the workpiece in a vice and using a wooden gasket.

It is more difficult to drill a cylindrical workpiece tangentially. The process is divided into two operations: preparation of the site perpendicular to the hole (milling, countersinking) and the actual drilling. Drilling holes in angled surfaces also begins with site preparation, after which a wooden spacer is inserted between the planes, forming a triangle, and a hole is drilled through the corner.

The hollow parts are drilled by filling the cavity with a wood cork.

Shoulder holes are produced using two techniques:

1. Reaming. The hole is drilled to the full depth with a drill of the smallest diameter, after which it is reamed to a given depth with drills with diameters from smaller to larger. The advantage of the method is a well-centered hole.
2. Reducing the diameter. A hole of the maximum diameter is drilled to a given depth, then the drills are changed with a sequential decrease in the diameter and deepening of the hole. This method makes it easier to control the depth of each step.

1. Reaming the hole. 2. Reducing the diameter

Large holes, circular drilling

Obtaining large-diameter holes in massive workpieces, up to 5-6 mm thick, is a laborious and costly business. Relatively small diameters - up to 30 mm (maximum 40 mm) can be obtained using tapered, or better step-taper drills. For holes with a larger diameter (up to 100 mm), you will need hollow bimetallic or carbide-tipped bits with a center drill. Moreover, craftsmen traditionally recommend Bosch in this case, especially on hard metal, for example, steel.

This hole drilling is less energy intensive, but can be more costly. In addition to drills, the power of the drill and the ability to work at the lowest speeds are important. Moreover, the thicker the metal, the more you will want to make a hole on the machine, and with a large number of holes in a sheet with a thickness of more than 12 mm, it is better to immediately look for such an opportunity.

In a thin-sheet blank, a large-diameter hole is obtained with the help of narrow-toothed crowns or a milling cutter fixed on a "grinder", but the edges in the latter case leave much to be desired.

Deep holes, coolant

Sometimes a deep hole is required. In theory, this is a hole that is five times its diameter. In practice, deep drilling is called drilling, requiring periodic forced removal of chips and the use of coolants (cutting fluids).

In drilling, coolant is needed primarily to reduce the temperature of the drill and workpiece, which are heated by friction. Therefore, when making holes in copper, which has a high thermal conductivity and is itself capable of removing heat, the coolant can be omitted. Cast iron can be drilled relatively easily and without lubrication (except for high-strength ones).

In production, industrial oils, synthetic emulsions, emulsols and some hydrocarbons are used as coolant. In home workshops, you can use:

• technical vaseline, castor oil - for mild steels;
• laundry soap - for aluminum alloys such as D16T;
• a mixture of kerosene with castor oil - for duralumin;
• soapy water - for aluminum;
• turpentine diluted with alcohol - for silumin.

The universal refrigerated liquid can be prepared independently. To do this, you need to dissolve 200 g of soap in a bucket of water, add 5 tablespoons of engine oil, you can waste it, and boil the solution until a soapy homogeneous emulsion is obtained. Some craftsmen use lard to reduce friction.

Deep holes can be made with solid and circular drilling, and in the latter case, the central rod, formed by the rotation of the crown, is not broken out entirely, but in parts, weakening it with additional small-diameter holes.

Solid drilling is performed in a well-fixed workpiece with a twist drill, into the channels of which coolant is supplied. Periodically, without stopping the rotation of the drill, you need to remove it and clean the cavity from chips. Work with a twist drill is performed in stages: first, take a short one and drill a hole, which is then buried with a drill of the appropriate size. If the hole depth is significant, it is advisable to use jig bushings.

If you regularly drill deep holes, you can recommend purchasing a special machine with automatic coolant supply to the drill and accurate centering.

Drilling by marking, template and jig

You can drill holes according to the made markings or without them - using a template or a jig.

Marking is done with a center punch. With a hammer blow, a place is marked for the tip of the drill. You can also mark the place with a felt-tip pen, but the hole is also needed so that the tip does not move from the intended point. The work is carried out in two stages: preliminary drilling, hole inspection, and final drilling. If the drill has "gone" from the intended center, notches (grooves) are made with a narrow chisel, guiding the point to the specified place.

To determine the center of a cylindrical blank, a square piece of sheet metal is used, bent at 90 ° so that the height of one shoulder is approximately one radius. Applying a corner on different sides of the workpiece, draw a pencil along the edge. As a result, you have an area around the center. You can find the center by the theorem - the intersection of perpendiculars from two chords.

The template is needed when performing a series of similar parts with several holes. It is convenient to use it for a pack of thin-sheet blanks connected by a clamp. In this way, several drilled workpieces can be obtained at the same time. Instead of a template, a drawing or diagram is sometimes used, for example, in the manufacture of parts for radio equipment.

The conductor is used when the accuracy of maintaining the distances between the holes and the strict perpendicularity of the channel are very important. When drilling deep holes or when working with thin-walled tubes, in addition to the conductor, guides can be used to fix the position of the drill relative to the metal surface.

When working with a power tool, it is important to remember about human safety and avoid premature wear of the tool and possible marriage. In this regard, we have collected some useful tips:

1. Before work, you need to check the fastenings of all elements.
2. When working on a machine or with an electric drill, clothes should not contain elements that can get under the influence of rotating parts. Protect your eyes from shavings with goggles.
3. The drill, when approaching the surface of the metal, must already rotate, otherwise it will quickly become dull.
4. It is necessary to remove the drill from the hole without turning off the drill, reducing the speed if possible.
5. If the drill does not go deep into the metal, then its hardness is lower than that of the workpiece. Increased hardness in steel can be detected by drawing a file over the sample - the absence of traces indicates increased hardness. In this case, the drill must be selected from carbide with additives and work at low speeds with a small feed.
6. If the small diameter drill does not fit well in the chuck, wind a few turns of brass wire around the shank, increasing the grip diameter.
7. If the surface of the workpiece is polished, place a felt washer over the drill to ensure that no scratches occur even when touching the drill chuck. When securing polished or chromed steel workpieces, use cloth or leather spacers.
8. When making deep holes, a rectangular piece of polystyrene, mounted on a drill, can serve as a gauge and, at the same time, rotate to blow off small chips.

Drilling large holes no problem if you choose the right tool. For example, such work may be necessary to secure the channel or metal corner... The easiest way is to use an electric drill, but it takes a lot of effort to get a hole with a diameter of, for example, 15 mm. To drill a large hole in metal, special tools and core drilling technology are used.

Features of creation

When drilling, it must be borne in mind that a castellated or stepped taper nozzle must be selected so that it has a smaller diameter than the hole to be created.

When using different tools, it is also necessary to take into account their peculiarities. For example, when reaming with tapered products, smooth edges are obtained.

Drill attachments

There are several attachments for drills that make the process easier and make big hole even:

• Drilling jig. Such a device is a body in which there are several guide sleeves for drills of different diameters. The material used to create the bushings is harder than drills, so you don't have to worry about the tool deflecting to the side while drilling and expanding the hole.
• Drill guide. Such a product allows you to fix the tool in such a way that during drilling it does not deviate to the side. In the absence of such a product, the tool may move to the side, which will lead to an uneven edge. It can also be fixed at an angle. But when drilling metal products, this is usually not required.
• Drill stand. Such a hand-made product can be an inexpensive replacement for a drilling machine, since it allows you to more comfortably carry out work. The fixed tool, when using the stand, moves along the bar with a lever. At the same time, displacement is completely excluded, since the workpiece to be drilled is reliably held due to the presence of a clamp.

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

Deep hole feature

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

When working without specialized tools, do not recessed the nozzle more than 2/3 of its length. For cooling during operation, you must use water. If the work is done in several approaches, the angle cannot be changed.

Feature 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. Metal crowns are similar to concrete and drywall products. The only difference is in the material used to create the cutting edge.

Also, drilling can be performed with standard products in several stages. For this, a small diameter nozzle is used first. The larger tool is then selected.

The most convenient way is to use cone drills. Such devices allow you to drill a hole in one go big size... To do this, the tool is simply sunk into the material.

Hassle-free drilling

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

Before carrying out work on the workpiece, a circle is marked for the hole, and the second circle will be less than the first by a distance equal to the diameter of the drill used. After that, 2 holes are marked in opposite places of the circle. It is necessary to step back 3 mm from them and mark the places for drilling. Thus, drilling occurs along the entire drawn circle. If necessary, some parts will have to be processed with a chisel. This will create jagged edges that will need to be sharpened. It is important to ensure that during the work there is no increase in the circumference, that is, 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 and cylindrical. The cutting edge removes all burrs, so the edge is smooth. At the end of the drill head there is a sharpened point that allows pre-drilling of the material.

Using such products you can:

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

With the step drills, it is possible to 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 a tool with low speed and high torque;
• sensitivity even to slight distortions.

In spite of indicated disadvantages, this nozzle allows you to conveniently work with metal plates, quickly drilling a circle of the desired diameter.

Metal crown

Metal processing is a complex process, therefore such work is usually performed using specialized equipment. To perform work in a domestic environment, 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. Products consist of several parts:

• crown;
• centering nozzle;
• product shank;
• screws that are needed for fastening.

When using a core drill, the work speed is increased up to 10 times. Also, the advantages include the ability to accurately drill in the range from 1.2 to 15 cm.

At the same time, there is no need to center during drilling. It is also worth noting that such drills have a higher wear resistance compared to spiral drills.

Before starting work, the installation is carried out center drill into the center of the circle, after which drilling is carried out. After that, the drill is retracted and the work is carried out with a crown.

Hole press

One of the most common methods is punching with special press... It goes like this:

1. First, the workpiece is placed on the press table and gripped by several clamps.
2. Then the metal is moved under the punching tool. At this stage, additional fastening of the material takes place with the help of a clamping ring.
3. At the last stage, the punch is punched.

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

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