How to quickly make a hole in metal. How to drill metal

In the field of repair, the ability to drill correctly is one of the basic ones. In addition to the general rules, it is important to take into account all the nuances when working with a specific material: concrete, tiles, metal, etc. All issues related to drilling will be covered in this article.

As already mentioned, drilling is the most common occupation for a repairman, and therefore it is important to immediately learn a few basic rules associated with this occupation.

• Using the right toolkit. There are many drills, each of which is designed for a certain kind of material. Therefore, you should not try to drill concrete with a wood drill and vice versa. It is also important to consider the conditions in which the tool will be operated. For example, industrial drills cannot be used for interior repairs (this is simply unsafe). It is also important to consider moisture resistance: for outdoor work, an IP34 class tool will be required if the climate in the area is humid and IP32 if the weather is to be worked in good weather. Indoor use IPX2/
• Smart markup. Before starting any work, it is important to carefully and accurately mark the drilling locations with a marker. You can still stick paper tape under the marker so that the drill does not slide over the material.
• Select the required drilling speed. It all depends equally on both the material and the diameter of the blade. If we are talking about very thin drills (with a diameter of less than 3 mm), then you need to work at low speeds, less than four hundred per minute. For other drills, there is the following rule: the thinner the drill, the greater the drilling speed required.

In addition, it is important to ensure that the handle is securely attached to the hand drill shaft. Also, the drill should not be twisted.

Drilling subtleties for various materials

How to drill metal correctly + (Video)

The first thing to start with is the selection of drills. They are distinguished by a sharp edge designed for easy entry of the drill into the metal. Ordinary metal drills are good for not too solid metals like copper or aluminum, but for something harder (for example, for stainless steel), you need to take products made of titanium carbide or chrome-vanadium alloy.

Separately, we should talk about optimal speeds. A common mistake novice craftsmen make is to use too many turns. In fact, for hard metals, medium speeds are used: for example, brass a centimeter thick will optimally be drilled at a speed of 2000-2500 revolutions.

There are a few more points that need to be covered. So:

• If you want to drill a thin iron plate, it must be fixed between two pieces of wood. This is done so that the sheet of metal does not break.
• It is necessary to use lubricating oil from time to time to keep the drill cool and make drilling easier.
• If you want to make a hole in the pipe, then it must be securely fixed. To prevent the pipe from flattening under the influence of a drill, a piece of hard wood should be placed inside.

If guided by these simple rules, then even a beginner will be able to perform high-quality drilling.

How to drill concrete walls + (Video)

Drilling into the walls Everyday life most often, because without this it is impossible to hang a shelf, a locker, you cannot install a cornice. Of course, it is better to use a puncher for this purpose or impact drill. These tools are powerful enough to handle hard material like concrete or brick. However, if the wall thickness does not exceed 10-12 cm, then you can get by with an ordinary drill. But it’s not worth the risk if you only have a low-power tool at your disposal - upon contact with concrete, it can simply break. If the drill is chosen correctly, then the following tips will be useful:

Though drill through concrete wall using a drill is generally real, but it is worth doing it with caution. Otherwise, damage can be quite serious. It is better to use specialized tools for this.

How to work with tiles with a drill + (Video)

Often, people who do not have rich experience in the field of repair are afraid to drill such fragile material as a tile. However, this can become an urgent need, because you need to attach various cabinets and shelves to something in the kitchen, bathroom or toilet. Alas, in many respects the state of the tile after drilling is determined not by the master who takes up the drill, but by the one who laid this tile. A competent tiler lays the tiles so that no voids form between the tile and the wall. In this case, careful drilling will in no way harm the tile. If there are “air pockets” between the wall and the tile, then most likely the tile will crack.

In order to properly drill a tile, you need to take a drill, masking tape, a hammer drill (or a powerful drill with concrete drills). Next, you will need to perform the following steps:

1. The drilling site is marked with a piece of masking tape and a marker. The adhesive tape is here so that the nail does not slip on the surface of the tile.
2. Drilling is carried out strictly perpendicular to the material. The number of revolutions should increase gradually: from the minimum possible to 150-200 revolutions per minute. In this way, damage to both the material and the tool can be avoided.
3. It is important to ensure that the drill does not overheat. If smoke began to go, then the drill must be urgently cooled.

When the holes are made, dowels can be inserted into them. This is done with a hammer.

Drilling cast iron - how to do it correctly + (Video)

Cast iron is a fairly hard material, so drilling it is very, very difficult. In addition, cast iron products are fragile, so it is important not to crush them. Like other materials, cast iron has its own subtleties when it comes to drilling.

• No rush. This is perhaps the most important rule when working with cast iron. Everything must be done slowly, with extreme care and attention.
• The drill must be of a very hard and durable alloy, in addition, it must be perfectly sharpened. In order for the cast iron not to crumble, it is necessary to take drills with an angle of 114-119 degrees.
• The drill must not overheat. Sometimes they don't pay attention to the fact that the tool is overheated. And this can lead to poor-quality performance of work or even breakage.

How to accurately drill through wood + (Video)

Wood is one of the most "simple" materials when working with a drill. However, even here there are subtleties.

• Drilling speed depends on the type of wood. Loose, not too hard woods will be within the power of even a low-power apparatus. Of course, the estimated diameter of the hole also plays a role - the larger it is, the more powerful the drill is needed.
• To make holes big size, it is necessary to use special drill-crowns. Their diameter can exceed 120 mm. As for depth, on average crowns are suitable for materials up to 20-22 mm thick, but there are also special models that can cope with a thickness of more than 60 mm.
• If you need to make a deaf, not through hole, then Forstner drills, which are available in diameters from 1 to 5 cm, are perfect for this.

Separately, it is worth talking about drilling a bar. Although it is convenient to fix it for further drilling, the large thickness of the material creates certain difficulties. Drilling a beam for further fixing in the holes of the dowels. For a standard timber with a thickness of 18 cm, it would be best to take a drill with a diameter of 25 mm and a length of 36 cm. You will need to drill slowly, at low speeds. In terms of power, a 1300-1500 watt drill is perfect. If the beam is not very long, then two holes on each side will suffice. If the length of the beam under the dowels is large enough, then it will be necessary to make an additional hole in the center. After the holes are made, dowels can be hammered into them with a hammer or a small sledgehammer.

At what RPM should drilling be done?

One of the important parameters when drilling is the number of revolutions per minute. The speed at which you need to drill depends on the kind of material and the type of drill. There is general rule: The harder the material and the thicker the roll, the lower the number of revolutions per minute should be. As for specific figures, they can be seen in the table below.

This table is for conventional twist drills. For specific applications (Frostner drill, etc.) drilling speed various materials somewhat different from those above.

How to drill a hole evenly + (Video)

A fairly common problem is that the drill slips off the mark, and the hole is made in the wrong place. Paper tape glued on top of a tree can help to deal with this. Also, sometimes such difficulties arise if you have to work with an overly thick drill. Then you should first make a recess in the material with a thinner drill, and then drill, resting against the mark made.

It is important to pay attention to the quality of sharpening. If the edges are not sharp enough or sharpened unevenly, then there may be problems with the accuracy of drilling.

How to drill a perpendicular and vertical hole

Although it is sometimes necessary to drill at an angle, most often vertical holes (that is, perpendicular to the surface) are made. In order for drilling to take place strictly at an angle of 90 degrees, it is necessary to use special guides. They will allow you to drill perpendicularly, without deviating in any direction.

The simplest guides allow you to make only vertical holes, but there are more complex structures allowing drilling at certain angles.

Drilling metal with a drill is somewhat more difficult than wood, brick or concrete. There are also some features.

For convenience, we have combined practical advice on this type of work into step-by-step instructions.

1. You will need the following tools: a drill, a drill, coolant (machine oil is better, but water is also possible), a center punch, a hammer, goggles.
2. When drilling metal on a horizontal surface, we put a wooden block under the product and fix it as best as possible. When working in a vertical position, rigid fixation is extremely important, since drilling must be strictly perpendicular.
3. We make markings, after that, using a center punch and a hammer, we outline the center of the future hole.
4. Pour coolant into a small container.
5. We put on protective goggles.
6. We start drilling. Do not exert strong pressure on the drill, because it is better to work at low speeds. If the drill is powerful, then the method of short-term inclusions is suitable, until the tool has had time to gain maximum speed.
7. Do not forget to cool the drill as often as possible .
8. When drilling is not strictly perpendicular, but at an angle, it is likely that the drill will jam. If this happens, put the switch in the reverse position. So you avoid injury and do not break the drill.
9. If everything was done correctly, then even at home, using a low-power drill, you can drill a hole in metal up to 5 mm thick inclusive and up to 10-12 mm in diameter. More complex tasks will be discussed below.

Metal drilling work

Can you drill metal with a concrete drill?

It is possible, but this is in case of emergency for not deep holes with small diameter. Unprofitable.

It is better to use either standard metal drills with steel grade R6M5 or improved - R6M5K5.

The letter K in the marking indicates that this is an alloy with the addition of cobalt. On the market you can find a drill, which is called "Cobalt". We will not vouch for all manufacturers, we only note that reviews on practical application in the vast majority of cases they are positive.

Hole drilling is a type of metal processing by means of rotating devices by cutting. This operation is divided into deep drilling and conventional. In the first option, the depth of the hole is more than 10 cm or has a size of more than 5 available diameters (d * 5). With drills, it is possible to achieve recesses of different depths and diameters (with several cross-sectional faces).

Drilling holes in metal is possible in one of the following ways:

1. The workpiece is rotated and at the same time the longitudinal feed of the non-rotating drilling tool is performed.
2. The workpiece does not rotate, it assumes a fixed position.
3. Simultaneous movement around its axis of both the mechanism and the part.

In practice, these technologies are quite in demand. The procedure for forming deep holes is in great demand in such areas as the manufacture of pipes, metallurgy, aerospace and oil and gas industries, the production of heat exchanger plates, etc. Deep holes often have to be made on the following parts: axles, sleeves, bandages, shafts, rotors, bushings, cylinders , metal shells, etc.

Deep Hole Drilling: Classification

1. According to the type of removal of the drilled content (chips), they distinguish: annular and continuous procedures. In the second method, the drilled content is removed like chip particles, in the first one, the annular plane is partially removed like a rod, and the other part is shaving.
2. According to the cutting method, technologies are distinguished:

Single bar (STS). This method Ideal for making workpieces in a high throughput or mass production process. The problem here is that you have to use the oil receiver with a variety of supply hoses while rotating the part. This system is recognized as the most effective in the formation of holes of high quality.

Ejector. Deep processing option with medium quality parameters. Processing is carried out on lathes with many complex functions. The system involves the use of an additional mobile or installed pumping station. This method allows you to get holes with a diameter of 2 to 6 cm in depth up to 120 cm, including intermittent.

Rifle (tubular-blade) drills with the supply of a cooling and lubricating agent from the inside. This option is suitable for small enterprises in which it is planned to obtain holes of small diameter under the conditions of technology.

Drills with a single cutter are easily built into machines with a universal principle of operation. The cutter is made of hard alloys and has a V-shaped groove along the entire length of the rod. The refractive angle of the latter can reach 110-1200º. The recommended diameter for drilling is 3.5-4.0 cm, length is d * 50. This method does not provide for deployment and reaming operations.

Automatic process control allows you to select: deep impact with an automated change of one or many regime parameters (lubrication supply, rotation speed, etc.).

Back to index

Characteristics of the deep drilling process

In deep processing, the basic principles of the technological process are observed.

Initially, the rotational speed of the drilling part of the equipment or the maximum possible cutting speed (drill feed) is selected.

They monitor the provision of normal chip crushing, the removal of the contents from the recesses completely.

An important nuance at the time of excision of waste is the safety of the cutter of the tool. In this part, the drill should not have damage, as well as burrs and other flaws. Another key criterion for effective metal surface treatment is the correct supply of coolant and lubricant.

Since the parts are drilled, accompanied by the supply of coolant and lubricant with a certain pressure and with a given flow rate, the operation of pumping devices is introduced into the system - oil pumps or pumps for pumping viscous substances.

The power of the system is selected based on the consumption of fluid and the required pressure to supply the lubricant.

Liquid supply is an indispensable point of technology:

1. Chips are correctly ejected from working area through the output channels.
2. The force of friction between the contacting elements is reduced.
3. The removal of excess heat generated during the procedure of long drilling is carried out, while the safety of the drill is ensured.
4. Additional processing of the excavation is carried out.

The work of drilling holes in metal, depending on the type of holes and the properties of the metal, can be performed different instrument and using various methods.

We want to tell you about drilling methods, tools, as well as safety precautions when performing these works.

Drilling holes in metal may be needed when repairing engineering systems, household appliances, car, creating structures from sheet and profile steel, designing crafts from aluminum and copper, in the manufacture of circuit 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 obtained desired 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 hand 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 various designs 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, large 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 - short, elongated and long are produced. important information is the ultimate hardness of the metal being processed. The shank of the drills can be cylindrical and conical, which should be borne in mind when selecting a drill chuck or adapter sleeve.

1. Drill with a cylindrical shank. 2. Tapered shank drill. 3. Drill with a sword for carving. 4. Center drill. 5. Drill with two diameters. 6. Center drill. 7. Conical drill. 8. Conical multi-stage drill

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

Various types of drill sharpening. 1. For hard 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 parts before drilling, a vice, stops, conductors, corners, clamps with bolts and other devices are used. This is not only a safety requirement, it is actually more convenient, and the holes are of better quality.

To chamfer and process the surface of the channel, they use a countersink of a cylindrical or conical shape, and to mark a point for drilling and so that the drill does not “jump off” - a hammer and a center punch.

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

Drilling modes

It is very important to correctly fix and guide the drill, as well as 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 penetration of the drill at one revolution (mm / rev). When working with various metals and drills, it is recommended various modes cutting, and the harder the metal being processed and the larger the diameter of the drill, the lower the recommended cutting speed. An indicator of the correct mode is a beautiful, long chip.

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

Feed S 0 , mm/rev	Drill diameter D, mm
	2,5	4	6	8	10	12	146	20	25	32
	Cutting speed v, m/min
When drilling steel
0,06	17	22	26	30	33	42	-	-	-	-
0,10	-	17	20	23	26	28	32	38	40	44
0,15	-	-	18	20	22	24	27	30	33	35
0,20	-	-	15	17	18	20	23	25	27	30
0,30	-	-	-	14	16	17	19	21	23	25
0,40	-	-	-	-	-	14	16	18	19	21
0,60	-	-	-	-	-	-	-	14	15	11
When drilling cast iron
0,06	18	22	25	27	29	30	32	33	34	35
0,10	-	18	20	22	23	24	26	27	28	30
0,15	-	15	17	18	19	20	22	23	25	26
0,20	-	-	15	16	17	18	19	20	21	22
0,30	-	-	13	14	15	16	17	18	19	19
0,40	-	-	-	-	14	14	15	16	16	17
0,60	-	-	-	-	-	-	13	14	15	15
0,80	-	-	-	-	-	-	-	-	-	13
When drilling aluminum alloys
0,06	75	-	-	-	-	-	-	-	-	-
0,10	53	70	81	92	100	-	-	-	-	-
0,15	39	53	62	69	75	81	90	-	-	-
0,20	-	43	50	56	62	67	74	82	–	–
0,30	-	-	42	48	52	56	62	68	75	-
0,40	-	-	-	40	45	48	53	59	64	69
0,60	-	-	-	-	37	39	44	48	52	56
0,80	-	-	-	-	-	-	38	42	46	54
1,00	-	-	-	-	-	-	-	-	-	42

Table 2. Correction factors

Table 3. Revolutions and feeds for various drill diameters and drilling in carbon steel

Types of holes in metal and methods for drilling them

Types of holes:

• deaf;
• through;
• half (incomplete);
• deep;
• large diameter;
• for internal thread.

Threaded holes require the determination of diameters with tolerances established in GOST 16093–2004. For common hardware, the calculation is given in table 5.

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

Metric thread				Inch thread				Pipe thread
Thread diameter	Thread pitch, mm	Thread hole diameter		Thread diameter	Thread pitch, mm	Thread hole diameter		Thread diameter	Thread hole diameter
		min.	Max.			min.	Max.
M1	0,25	0,75	0,8	3/16	1,058	3,6	3,7	1/8	8,8
M1.4	0,3	1,1	1,15	1/4	1,270	5,0	5,1	1/4	11,7
M1.7	0,35	1,3	1,4	5/16	1,411	6,4	6,5	3/8	15,2
M2	0,4	1,5	1,6	3/8	1,588	7,7	7,9	1/2	18,6
M2.6	0,4	2,1	2,2	7/16	1,814	9,1	9,25	3/4	24,3
M3	0,5	2,4	2,5	1/2	2,117	10,25	10,5	1	30,5
M3.5	0,6	2,8	2,9	9/16	2,117	11,75	12,0	-	-
M4	0,7	3,2	3,4	5/8	2,309	13,25	13,5	11/4	39,2
M5	0,8	4,1	4,2	3/4	2,540	16,25	16,5	13/8	41,6
M6	1,0	4,8	5,0	7/8	2,822	19,00	19,25	11/2	45,1
M8	1,25	6,5	6,7	1	3,175	21,75	22,0	-	-
M10	1,5	8,2	8,4	11/8	3,629	24,5	24,75	-	-
M12	1,75	9,9	10,0	11/4	3,629	27,5	27,75	-	-
M14	2,0	11,5	11,75	13/8	4,233	30,5	30,5	-	-
M16	2,0	13,5	13,75	-	-	-	-	-	-
M18	2,5	15,0	15,25	11/2	4,333	33,0	33,5	-	-
M20	2,5	17,0	17,25	15/8	6,080	35,0	35,5	-	-
M22	2,6	19,0	19,25	13/4	5,080	33,5	39,0	-	-
M24	3,0	20,5	20,75	17/8	5,644	41,0	41,5	-	-

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 tabletop from the exit of the drill beyond the workpiece, which can damage the drill itself, as well as provide the workpiece with a “burr” - a hart. To avoid this, use the following methods:

• use a workbench with a hole;
• put a gasket made of wood or a “sandwich” under the part - wood + metal + wood;
• put a metal bar under the part with a hole for the free passage of the drill;
• reduce the feed rate at the last stage.

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 spatula 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 an adjustable stop chuck;
• using a ruler fixed on the machine;
• a combination of methods.

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

Holes of complex shape

Holes located on the edge of the workpiece (half) can be made by connecting two workpieces or a workpiece and a gasket with faces and clamping with a vise and drilling a full hole. The gasket must be made of the same material as the workpiece being processed, otherwise the drill will “leave” in the direction of least resistance.

A through hole in the corner (shaped rolled metal) 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 a platform perpendicular to the hole (milling, countersinking) and drilling itself. 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.

Hollow parts are drilled, filling the cavity with a cork made of wood.

Stepped 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 drilled 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 maximum diameter is drilled to a given depth, then the drills are changed with a successive decrease in diameter and a hole deepening. With this method, it is easier to control the depth of each step.

1. Drilling a hole. 2. Diameter reduction

Large diameter holes, annular drilling

Obtaining holes of large diameter in massive workpieces, up to 5–6 mm thick, is a laborious and costly task. Relatively small diameters - up to 30 mm (maximum 40 mm) can be obtained using cone, and preferably step-cone drills. For holes with a larger diameter (up to 100 mm), hollow bi-metal hole saws or hole saws with carbide teeth with a center drill will be required. Moreover, the craftsmen traditionally recommend Bosch in this case, especially on hard metal, such as steel.

Such annular drilling is less energy-intensive, but may be more financially 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 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 using narrow-toothed crowns or a milling cutter mounted 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 whose length is five times the diameter. In practice, deep drilling is called, requiring forced periodic removal of chips and the use of coolants (coolants).

In drilling, coolants are 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, coolant can be omitted. Cast iron is drilled relatively easily and without lubrication (except for high-strength ones).

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

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

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

Processed material	Coolant
Steel:
carbonaceous	Emulsion. Sulfurized oil
structural	Sulfurized oil with kerosene
instrumental	Blended oils
alloyed	Blended oils
Ductile iron	3-5% emulsion
Cast iron	Without cooling. 3-5% emulsion. Kerosene
Bronze	Without cooling. Blended oils
Zinc	Emulsion
Brass	Without cooling. 3-5% emulsion
Copper	Emulsion. Blended oils
Nickel	Emulsion
Aluminum and its alloys	Without cooling. Emulsion. Mixed oils. Kerosene
Stainless, high temperature alloys	Mixture of 50% sulfurated oil, 30% kerosene, 20% oleic acid (or 80% sulfofresol and 20% oleic acid)
Fiber, vinyl plastic, plexiglass and so on	3-5% emulsion
Textolite, getinaks	Compressed air blowing

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

Solid drilling is performed in a well-fixed workpiece with a twist drill, through the channels of which coolant is supplied. Periodically, without stopping the rotation of the drill, it is necessary to remove it and clean the cavity from chips. The work with a twist drill is carried out in stages: first, a short hole is taken and a hole is drilled, which is then deepened with a drill of the appropriate size. With a significant depth of the hole, it is advisable to use guide bushings.

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

Drilling by marking, template and jig

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

Marking is done with a punch. A hammer blow marks a place for the tip of the drill. A felt-tip pen can also mark a place, but a 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 control, final drilling. If the drill "left" from the intended center, notches (grooves) are made with a narrow chisel that guide the tip to a given place.

To determine the center of a cylindrical workpiece, a square piece of tin is used, bent at 90 ° so that the height of one shoulder is approximately one radius. Applying a corner from 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.

A template is needed when making a series of parts of the same type with several holes. It is convenient to use it for a pack of thin-sheet blanks connected with a clamp. This way you can get several drilled blanks 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 human safety and prevent 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 fastening of all elements.
2. Clothing when working on a machine or with an electric drill should not be with elements that can fall under the action of rotating parts. Protect your eyes from chips 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 running a file over the sample - the absence of traces indicates increased hardness. In this case, the drill must be selected from a carbide with additives and work at low speeds with a small feed.
6. If a small diameter drill does not fit well in the chuck, wind a few turns of brass wire around its shank, increasing the diameter to grip.
7. If the surface of the workpiece is polished, put a felt washer on the drill to ensure that it does not scratch even when it comes into contact with the drill chuck. When fastening workpieces made of polished or chrome-plated steel, use spacers made of fabric or leather.
8. When making deep holes, a rectangular piece of foam placed on a drill can serve as a measuring instrument and at the same time, while rotating, blow off small chips.

Today everyone has home master available essential tool for metal cutting, drilling, stripping. But what if you need to drill a large 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 of more than 20 mm. For this, special devices are used:

• Cone drill. A large number of holes of the same size cannot be drilled. But for home use it is quite acceptable. The maximum section is up to 40 mm. The thickness of the processed metal is 5-6 mm.
• Cone step drill. It is more convenient to use, since each of its steps is formed by a smooth spiral transition. When drilling, this makes it easy to track the actual diameter of the hole. With it, you can drill a circle up to 40 mm in diameter on metal up to 6 mm thick.
• Bimetal 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 lubricants and coolants, which will ensure the maximum operational life of the cutting tool. Also, an adapter is required to install the device on an electric drill. On average, 5-20 openings can be drilled with a bimetallic crown, depending on its quality, which, accordingly, is reflected in the cost.

How can you drill a large hole at no extra cost?

For this method, you will need a small-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 hole diameter) for the grinder. The option is more laborious, so it takes much more time.

2 circles are marked on a metal blank 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 less than the previous one.

On the 2nd circle, it is necessary to punch 2 places in opposite places and drill holes with a 6 mm drill. From the received openings along the intended line, you need to retreat about 3 mm and again mark the places for drilling. Holes are drilled along the contour of the entire circle. If necessary, the remaining sections can be chopped 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. With a grinder, you can quickly and evenly bore a hole to the required diameter.

Therefore, you should not throw away used abrasive wheels for a grinder with a diameter of even less than 45 mm - they can always come in handy on the farm.