How and how to drill deep and large holes in metal parts. How to drill hardened steel at home How to make holes in metal

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 which 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 a tapered 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 workable 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 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 plating is 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.

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. 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

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
Thread diameter	Thread pitch, mm	min.	Max.	Thread diameter	Thread pitch, mm	min.	Max.	Thread diameter	Thread hole diameter
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	—	—
М4	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
М8	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	—	—
М16	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 table top from the drill going beyond the workpiece, which can damage the drill itself, as well as provide the workpiece with a "burr" - a garter. 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 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 spacer 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:

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.
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, 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 with a cutter fixed to 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 petroleum jelly, 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.

Processed material	Coolant lubricant
Steel:
carbonaceous	Emulsion. Sulfurized oil
structural	Sulfurized kerosene oil
instrumental	Mixed oils
alloyed	Mixed oils
Malleable cast iron	3-5% emulsion
Iron casting	No refrigeration. 3-5% emulsion. Kerosene
Bronze	No refrigeration. Mixed oils
Zinc	Emulsion
Brass	No refrigeration. 3-5% emulsion
Copper	Emulsion. Mixed oils
Nickel	Emulsion
Aluminum and its alloys	No refrigeration. Emulsion. Mixed oils. Kerosene
Stainless, heat-resistant alloys	A mixture of 50% sulfurized oil, 30% kerosene, 20% oleic acid (or 80% sulfofresol and 20% oleic acid)
Fiber, vinyl plastic, plexiglass and so on	3-5% emulsion
Textolite, getinax	Compressed air blowing

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. 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 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:

Before work, you need to check the fastenings of all elements.
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 eyes from shavings with goggles.
The drill, when approaching the surface of the metal, must already rotate, otherwise it will quickly become dull.
It is necessary to remove the drill from the hole without turning off the drill, reducing the speed if possible.
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 a carbide with additives and work at low speeds with a small feed.
If the small diameter drill does not fit well in the chuck, wind a few turns of brass wire around the shank, increasing the diameter to grip.
If the surface of the workpiece is polished, place a felt washer over the drill to ensure it does not scratch even when it touches the drill chuck. When securing polished or chromed steel workpieces, use cloth or leather spacers.
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.

Drills for metal are selected based on the diameters of the holes and the properties of the material being processed. As a rule, they are made of high-speed steels such as R6M5K5, R6M5, R4M2. Solid carbide drills are used to work with cast iron, carbon and alloy hardened steels, stainless steel, and other difficult-to-machine materials.

The power of the electric drill must be designed to drill a hole of the required diameter. Power tool manufacturers indicate the corresponding specifications on the product. For example, for drills with a power of 500 ... 700 W the maximum drilling diameter for metal is 10 ... 13 mm.

Distinguish between blind, incomplete, and through holes. They can be used to connect parts together by means of bolts, studs, pins and rivets. If the hole is being drilled for the purpose of tapping, it is worth paying particular attention to the choice of the drill diameter. Due to its beating, a hole breakdown occurs in the chuck, which must be taken into account. Indicative data are presented in the table.

To reduce the breakdown, drilling is performed in two stages: first with a smaller diameter drill, and then with the main one. The same method of sequential reaming is used when it is necessary to make a hole with a large diameter.

How to properly drill metal with a drill

The peculiarity of drilling metal with a drill is that it is necessary to manually hold the tool, give it the correct position, and also provide the required cutting speed.

After marking the workpiece, the center of the future hole should be punched. This will prevent the drill from moving away from the set point. For the convenience of work, the workpiece should be clamped in a locksmith's vice or put on a stand so that it takes a stable position. The drill is installed strictly perpendicular to the surface to be drilled. This is important to avoid breaking it.

When drilling metal, you do not need to exert much pressure on the drill. On the contrary, it should decrease as you go. This will prevent breakage of the drill and also reduce the formation of burrs on the trailing edge of the through hole. Care should be taken when removing chips. If there is a jamming of the cutting tool, it is released by reversing the rotation.

Choice of cutting mode

When using a HSS tool, the speed can be referenced according to the table. When working with carbide drills, the permissible values are 1.5 ... 2 times higher.

Drilling of metal products must be carried out with cooling. If not used, there is a high probability that the tool will lose cutting properties due to overheating. In this case, the surface finish of the hole will be rather low. An emulsion is commonly used as a coolant for solid steels. At home, machine oil is suitable. Cast iron and non-ferrous metals can be drilled without coolant.

Deep hole drilling features

Holes are considered deep if they are larger than five drill diameters. The peculiarity of the work here lies in the difficulties associated with cooling and removing chips. The length of the cutting part of the tool must be greater than the depth of the hole. Otherwise, the body of the part will overlap the helical grooves, along which the chips are removed, and also the liquid for cooling and lubrication enters.

First, the hole is drilled with a short, hard drill bit to a shallow depth. This operation is necessary to set the direction and centering of the main tool. After that, a hole is made of the required length. As you progress, you need to remove the metal shavings from time to time. For this purpose, use coolant, hooks, magnets or turn the part over.

Drilling through holes in metal workpieces is carried out with various tools using special techniques. Many specialists, when performing engineering work, have to drill holes in metal structures quite often. These objects are highly elastic, which forces the use of special cutting devices when drilling.

Drill types and tools for metal drilling

The necessary devices for drilling metal products are electric and hand drills, as well as drilling machines. The working part of such devices is a drill of various shapes:

spiral;
screw;
coronal;
conical;
flat;
cannon;
rifle;
centering;
stepped.

Each drill is individually marked, where the diameter of the section and the type of alloy from which it is made are indicated on the tip. To drill a hole of the required diameter, you need a drill a few tenths of a millimeter narrower.

Drills are also classified by length:

short;
elongated;
long.

Some materials may require a specially sharpened diamond tipped drill bit. Twist drills may not cope with products made of thin sheet alloys. In some cases, to drill deep holes, the product must be fixed in a vice, stops, conductors, corners with fasteners. This is done for safety reasons and for high quality holes.

Modes of drilling holes in metal products

For drilling through holes in metal products, preliminary preparation for the process is extremely important. The drill must be correctly fixed and guided in the tool. You need to adjust the speed and other parameters. For products that are too strong, a low drill speed is recommended. An indicator of correct drilling should be uniform long chips.

Hole types and drilling methods

In some production jobs, the following types of holes are often required in metal workpieces:

Through. Metal blanks are completely pierced. It is important to protect the surface of the machine from accidental drill out of the product to avoid damage to the drill and burrs on the blank. Workbenches with holes are ideal for such types of work, where it is possible to put a wooden pad under the workpiece. Holes in thin blanks are drilled with flat drills, because the twist drill can noticeably destroy the edges of the product.
Deaf. They are carried out to the required depth without penetrating the product through and through. In this case, an important point is to measure the depth, which is convenient to do by limiting the length of the drill with a bushing stop or a drill chuck with a fixing stop. Professional machines are equipped with automatic feeding systems for a given depth of penetration, which allows you to fix the depth of the drill entry.
Deep. This type of hole includes those drills whose length is five times the diameter. When drilling deep holes, it is necessary to periodically remove the resulting chips with the use of additional lubricants. It is often necessary to enforce measures to cool the drill and the workpiece itself, the temperature of which rises rapidly to too high a level as a result of friction. This applies to workpieces made of high-strength alloys. Twist drills are used for deep holes.
Wide diameter. Drilling holes of large diameter in products of large proportions is a very demanding and laborious process. For such holes, cone, crown-shaped or step drills are used. Specialists carry out reaming at low tool speeds, trying to ensure the safety of the edges of the workpiece.
Complex shape. Sometimes it is necessary to drill through or blind holes in workpieces of different densities for internal threads. The technology has to be divided into two steps: preliminary preparation of the site and the drilling itself.
Half. Half blanks are drilled, filling the cavities with wood. Recessed holes can be obtained by one of two techniques: reaming (passing a drill of a smaller diameter to the entire depth of the workpiece, followed by reaming with drills of a larger diameter) and decreasing the diameter (drilling a larger hole to the required depth with the subsequent replacement of a drill of a smaller diameter). The result is a well-centered hole.

Safety when drilling holes in metal workpieces

You should proceed with drilling holes in metal workpieces with great care, avoiding rapid destruction of the drill. Compliance with simple rules for drilling will ensure safety and guarantee the output of a quality product at the end of the work:

On the eve of drilling, it is necessary to carefully check the fixation of all fasteners on the machine.
You can start work in special clothing to prevent any elements from getting under the moving parts of the machine. Eyes are protected from metal shavings with special glasses.
When the drill tip enters the metal workpiece, it should already rotate at low speeds to avoid bluntness.
The drill should exit the drilled hole gradually, reducing the speed, but not stopping completely.
When the drill tip does not sink into the workpiece, the strength of the metal will have to be checked. When passing over the surface with a file, it is possible to determine the degree of strength. If there is no roughness on the alloy, you need to choose a drill with a diamond tip or a harder material, and drill at low speeds.
Small diameter drills, which are difficult to fix in the chuck, are recommended to be wrapped on the tail with brass wire to increase the girth diameter.
If you are working with a polished workpiece, you can put a felt washer on the base of the drill to avoid damage when it comes into contact with the drill chuck.
For fixing metal blanks made of polished or chrome-plated steel, fabric or leather spacers are used.
When drilling deep holes, a small piece of compressed foam on the drill will blow off small metal chips. Also, the foam will make it possible to deepen the drill to the required level when producing blind holes.

The power of electric drills must be taken into account when drilling holes in metal workpieces of different hardness. Manufacturers of electric tools mark their appliances by indicating the technical characteristics on their case. For drills of different capacities, drills of the corresponding diameter are suggested.

Any, including drilling, you can entrust to Proflazermet specialists. We ourselves will determine the required hole diameter and select the appropriate tool, of which we have a large selection. As a result, you will get the perfect solution in a short time.

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.

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 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.

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

For chamfering and processing the surface of the channel, 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”.

Drilling modes

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

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. 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

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
Thread diameter	Thread pitch, mm	min.	Max.	Thread diameter	Thread pitch, mm	min.	Max.	Thread diameter	Thread hole diameter
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	-	-
М4	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
М8	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	-	-
М16	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

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.

Complex holes

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

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

Shoulder holes are produced using two techniques:

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.
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

Making holes of large diameter in massive workpieces, up to 5–6 mm thick, is a laborious and costly process. 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.

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

Deep holes, coolant

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

technical petroleum jelly, 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.

Processed material	Coolant lubricant
Steel:
carbonaceous	Emulsion. Sulfurized oil
structural	Sulfurized kerosene oil
instrumental	Mixed oils
alloyed	Mixed oils
Malleable cast iron	3-5% emulsion
Iron casting	No refrigeration. 3-5% emulsion. Kerosene
Bronze	No refrigeration. Mixed oils
Zinc	Emulsion
Brass	No refrigeration. 3-5% emulsion
Copper	Emulsion. Mixed oils
Nickel	Emulsion
Aluminum and its alloys	No refrigeration. Emulsion. Mixed oils. Kerosene
Stainless, heat-resistant alloys	A mixture of 50% sulfurized oil, 30% kerosene, 20% oleic acid (or 80% sulfofresol and 20% oleic acid)
Fiber, vinyl plastic, plexiglass and so on	3-5% emulsion
Textolite, getinax	Compressed air blowing

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.

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:

Before work, you need to check the fastenings of all elements.
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 eyes from shavings with goggles.
The drill, when approaching the surface of the metal, must already rotate, otherwise it will quickly become dull.
It is necessary to remove the drill from the hole without turning off the drill, reducing the speed if possible.
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 a carbide with additives and work at low speeds with a small feed.
If the small diameter drill does not fit well in the chuck, wind a few turns of brass wire around the shank, increasing the diameter to grip.
If the surface of the workpiece is polished, place a felt washer over the drill to ensure it does not scratch even when it touches the drill chuck. When securing polished or chromed steel workpieces, use cloth or leather spacers.
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-diameter holes in metal is not a major problem now.... 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 a building structure or hang a shelf, lamp or pipeline. 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, economically viable only with 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, it 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 lubricant-cooling composition ensures that the upper bar of this range is reached. At the third stage there are bimetallic crowns of world famous brands, which are twice as expensive, can be equipped with special devices for quick change in the drill, but in terms of resource they do not much or do not exceed the average price level.

Drilling large diameter holes in steel sheets with a thickness of more than 5-6 mm for bimetallic bits is very difficult, although sometimes you 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 crown is not entirely cylindrical in shape, this causes jamming in the metal of a 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 large diameter metal that is the most progressive, providing the best performance and quality. The price of such crowns is 20-30% higher than that of thin-walled and in absolute terms is 1880 - 1910 rubles, as we agreed, for a crown with a diameter of 51 mm. As well 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, the investment 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 is definitely required. 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 manual 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.

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