Drilling metal at home. What and how to drill deep and large holes in metal parts

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 openings of the same size will not work. But for home use quite acceptable. The maximum section is up to 40 mm. The thickness of the processed metal is 5-6 mm.
• Tapered step drill. It is more convenient to use, since each 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.

On the metal blank 2 circles are marked 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 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.

Hello! About how to drill metal with a drill, if you wish, you can write a very long article. But I see two main problems here:

• inability to precisely drill in the place where a hole is required
• quick blunting of drills

Usually inexperienced users face such problems. Experienced men know what to do in such cases. Well, considering myself experienced, I will take the liberty of telling you how to deal with these problems. Well, I will also give a few tips that will also come in handy.

How to drill in the right place?

If you think a little about this question, then the answer should visit your head even without a hint. Well, it seems so to me at least. But if you don't feel like thinking, then read on.

For this case, you need a core. This is a tool made of durable steel, having a cylindrical shape and a point at the end.

We put the tip to the desired drilling site and hit the roll on the other side with a hammer several times.

Now, when you are centered, put a drill on the surface of the roughness and start drilling - the tip will not run away anywhere.

How not to dull drills?

Drill bits for metal become blunt if they get too hot during operation, due to which they lose their strength. Heating is due to friction. Moreover, the faster it spins, the more it heats up.

Hence the obvious rule - you need to drill at a low speed drill. They should be no more than 1000 per minute. But who will measure this at work? Therefore, just do not press the start button to the full. The correct speed can be estimated as follows: the eye should see the rotation of the drill. That is, the grooves on it should not merge into one for vision.

When working with thick workpieces, additional cooling is indispensable. It is provided by special lubricants or pastes that are added to the drilling site, or the drill is dipped into them. In addition, they not only cool, but also lubricate the tip, thereby reducing friction.

At home, there is no need to have special lubricants and pastes. You can get by with regular engine oil.

So, use a core, drill at low speeds, and add grease or oil, and then this thing will seem like a cakewalk to you.

Well, a few more tips on this topic.

Drill types

For drilling, take only drills for metal (and not for wood, for example). They have their own sharpening and are made of certain types of steel. The most common are marked P6M5 - these are high speed steel, which foreign manufacturers label as HSS.

To give additional strength to the above drills, a titanium nitride coating is applied. Because of what they are yellow.

There are also stronger P18s used for hard steels respectively.

Also, cobalt can be added to increase strength, and then the P6M5K5 marking is obtained.

Well, the most durable are drills with a carbide tip. They are used for drilling alloy steels. It will also take ordinary steel, but it will be somewhat prudent to buy it only for this, since the price for them is quite high, while it is solid, but still blunt. But it will be difficult to sharpen it later, since this requires a diamond blade, which is also not very cheap, and you can’t buy it everywhere.

Drilling thick workpieces

If the workpiece has a thickness of more than 5 mm, and you need a hole of more than 8 mm, then it is better to first make a hole with a thin drill, and only then work with a thick one.

Working with some types of metal

• When drilling thick aluminum workpieces, chips often clog the bores of the drill, making it harder to turn. Therefore, when working with such material, take the drill out of the recess more often and remove the chips. Oh, and don't forget to drizzle with plenty of oil.
• If you need to drill black cast iron, then for this you do not need to add any lubricating and cooling agents, since it is drilled very well even in the dry
• Unlike black cast iron, white cast iron has increased strength, which means that strong drills and lubrication will be required for its processing.

These are the basic rules for drilling metal with a drill. I hope I managed to fill this gap in your knowledge. Good luck with your homework and see you soon!

Produced by special cutting tool called a drill.

The drill, with constant rotation and constant axial movement, removes chips from the surface with its cutting edges and, gradually deepening into the thickness of the metal, throws the chips up, forming a cylindrical hole. The process of forming a hole with a drill is shown in fig. one.

The main cutting motion. Drill feed.

The rotary motion of the drill is called major labor movement or cutting motion. Translational movement along the axis of the drill is called drill feed.

Types of drilling holes.

There are the following types of drilling:

• - through, when the hole is drilled through;
• - deaf, when the hole is drilled to a certain depth of the part and has a bottom;
• - drilling an existing hole.

Drilling accuracy.

Rice. 1. Obtaining a hole when the drill rotates with the formation of chips.

The accuracy of drilling is ensured by the fact that the center of the drilled hole coincides with the center indicated by the marking and the intended diameter of the hole corresponds to the diameter of the drill. The last requirement is achieved by correct sharpening of the drill, checked by special templates. As for the coincidence of the center of the hole with the intended one, it depends on correct installation and the strength of fixing the product on the machine, on the quality of the metal, on the correct sharpening of the drill and on the accuracy of the machine. The product must be firmly fixed on the machine table or in a vise. Only large and heavy products may not be fixed if their weight ensures their immobility during drilling.

When marking holes, the center of the hole is marked, around which a control circle is drawn and punched. Before starting drilling, the center of the marked hole must be deepened, and for diameters over 25 mm and above, drilled with a small drill.

If during drilling the drill will begin to deviate to the side, then until it has gone completely into the metal, the hole must be straightened. To do this, on the surface of the resulting cone, it is necessary to cut a groove with a crosscut on the side opposite to that into which the drill has deviated. Then the drill is inserted into the groove and drilling continues. Grooving is repeated until the axis of the drill coincides with the axis of the control circle.

If you need to drill several blind holes of the same depth, use a pointer, which is a metal rod mounted on a cartridge. The lower end of the rod, reaching the top surface of the part, indicates that the drilling depth is sufficient.

Drilling holes away from the machine chuck, is made with the help of extensions, which at one end have a conical hole for inserting the tail of the drill into it, and at the other - a Morse cone for fixing the extension in the machine spindle.

If you need to drill holes in several identical parts, then instead of marking each, it is more profitable to mark one part and drill holes on it, and then drill the rest on the first part. This technique is called drilling parts by part.

Jig for drilling holes.

When drilling a large number of parts, they use a special device called conductor. Jig - a fixture with the required number of holes, into which hardened jig bushings are inserted to guide the drill. The shape and arrangement of conductors depend on the shape of the workpiece. The conductor is fastened to the product in which it is necessary to drill holes, and then drilling is performed. When drilling holes on the conductor, preliminary marking is not required. The bushings of the conductor must correspond to the diameter of the drill. Drilling thin workpieces, e.g. sheet metal, performed in batches. Sheets are fastened with clamps, and then drilling is performed.

Drilling holes on inclined planes.

At drilling parts with inclined planes of holes to the axis of the drill pre-drilling is required. To do this, the part with an inclined plane is initially set in such a way that its inclined plane is located in a horizontal position, and drilled, and then the part is set to its normal position and drilling is performed. Drilling holes in the side of round parts (rollers), when the axis of the roller is not in the same plane with the axis of the drill, is performed in the same sequence, i.e., the roller is turned so that its axes and the drill are in the same plane, and drilled, and then, turning the roller to its original position, drilling is performed.

Instead of drilling, in both cases, it is possible to make a hemming of the inclined plane of the part or roller, with the expectation that the drill will be fully stable when pressed.

Drilling deep holes in metal.

When drilling deep holes, the drill grooves, plunging into the product, are clogged with chips, as a result of which the drill is very hot, released, dulled and broken. To prevent this, the drill must often be removed from the hole and freed from chips. But it's better to do otherwise. Drilling is performed with two drills of different diameters: first, holes are drilled with a drill of a given diameter for a certain length, then they continue to drill to the end with a drill, the diameter of which is approximately 2 times less than the given diameter, and the operation is completed with a drill of a given diameter. When drilling with a large drill, the chips exit the product into a hole drilled with a small drill.

When drilling, the diameter of the resulting hole is always larger than the diameter of the drill, but when drilling viscous metals, such as steel, the development (expansion) of holes is less than when drilling brittle metals - cast iron, bronze. So when drilling, it is necessary to take into account the development of holes, which, with a drill diameter of up to 10 mm, increases the hole by 0.02-0.03 mm, and with a drill diameter of more than 10 mm, it reaches 0.05-0.1 mm. To get a more accurate hole size, you should drill twice: first with a drill of a smaller diameter, and then with a drill of the desired diameter.

Causes of drill breakage.

Breakage of drills can occur due to the presence of non-metallic inclusions, voids or cavities in the drilled product. When the drill exits, the mechanical feed must be halved or switched to manual. The transition to manual feed is necessary when drilling thin sheets and parts that have an inclined plane at the exit to the axis of the drill, in order to prevent breakage of the drill due to one-sided pressure on it.

When working with a blunt drill, breakage can also occur due to high feed and insufficient penetration of the drill into the metal.

Classification of drills by design.

By design, drills are divided into feather and spiral.

Feather drill.

Rice. 2. Perovoye drill.

Spade drill(Fig. 2) is made from a tool steel bar, one end of which is pulled and flattened, and the other end has a cylindrical or pyramidal shape. The first drill is used only in exceptional cases when drilling one or two holes. After each sharpening, the size of the drill decreases, and the holes are not the same.

Spiral drill.

Rice. 3. Twist drill.

1 – working part; 2 - neck; 3 - tail; 4 - leash; 5 - front cone; 6 - groove; 7 - pen; 8 - guide chamfer (ribbon); 9 - cutting edge (blade); 10 - transverse edge (blade); 11 - the surface of the rear sharpening.

Twist drills are widely used for drilling holes (Fig. 3).

Twist drills have significant advantages over feather drills. They provide high drilling performance, produce more accurate holes, maintain their diameter size after any number of sharpenings, have good chip evacuation and are well centered and guided into the hole.

Twist drill design.

By design, a twist drill consists of:

• intake cone with an angle at the top α equal to 116-120°. The corner at the top for soft metals is sharpened from 50 to 140 ° depending on the materials, for example, for plastic 50-60 °, for brass 100-110 °, for copper 125-130 °, for aluminum 140 °. The intake cone, due to the fact that when sharpening the cutting edges, a rear sharpening surface is formed, ends with a transverse rib-bridge. To remove chips and supply coolant emulsion, the cylindrical part has a helical groove with a helix angle of 26°;

• cylindrical or tapered drill tail with a Morse taper for fixing the drill in the spindle or chuck of the machine;

• paws (leash) for rotating the drill.

Drill sharpening. Correct sharpening of the drill.

Sharpening a drill requires a certain skill. Therefore, in modern, well-equipped workshops sharpening drills produced in a centralized manner on special machines with the use of devices. This ensures that the correct edges and cutting angles of the drill are obtained.

Template for sharpening drills.

The quality of sharpening the drill, the angle at the top and the angle of sharpening are checked with a template (Fig. 4). When sharpening, it is necessary to ensure that the cutting edges are inclined at the same angle to the drill axis, that the cutting edges are of the same length, and that the middle of the jumper is on the drill axis.

Rice. 4. Checking the sharpening of the drill with a template.

Coolant for drilling.

The durability of the drill, i.e., the operating time of the drill from one sharpening to another, depends on the correct cooling of the drill during operation. Without cooling, the cutting edges of the drill heat up, get tempered, and the drill becomes dull quickly. The coolant, the so-called emulsion, when drilling steel, ductile iron, red copper and brass is soapy water and mineral oil, and when drilling aluminium, soapy water and kerosene.

Gray and white cast iron, as well as bronze, are drilled without cooling (dry), since small chips, forming a viscous mass, increase friction and cause the tool to heat up.

Drill selection.

Hole drilling can be through and blind for threading and for reaming. The performance of one or another type of drilling does not affect the choice of drill, machine and method of fixing the product. The difference lies only in the selection of the diameter of the drill.

It is necessary to take into account the hardness of the metal being processed and, depending on it, select the diameter of the drill, taking into account that the drill develops a hole, i.e., makes it wider than its diameter.

The average development of holes is taken as follows:

Selection of a drill for threading table.

When drilling holes for threads, it is also necessary to keep in mind the hardness of the metal and, accordingly, select drills with it. For correct selection drills have special tables. One of these tables is shown below (Table 1).

Table 1. Selection of a drill for a thread.

Manual drilling.

For drilling holes by hand drills and ratchets.

The handwheel.

Rice. 5. Drill with bevel gears.

A hand drill (rotary) (Fig. 5) with bevel gears consists of a spindle 1, a chuck 2, two gears 3 and 4, handles 5 and 6 and a head 7. Spindle 1 rotates from a horizontally located bevel gear 3 connected to a vertical horse gear 4. Gear 4 is driven by handle 5. The drill is fixed in the chuck 2. The drill is held in time by handle 6 and head 7.

Ratchet.

Rice. 6. Ratchet.

The ratchet (Fig. 6) has a spindle 1, which is driven by the handle 2. A ratchet wheel 3 is mounted on the spindle, which is driven by the handle 2 through the dog. The dog is pressed against the ratchet wheel by a spring 4. When the handle moves in one direction, the pawl rotates the ratchet wheel, which in turn rotates the spindle with the drill inserted into it. When moving the handle to reverse side the pawl slides on the ratchet wheel, but does not rotate it. The feed is carried out by unscrewing the screw 5 from the nut 6 while the handle moves in the opposite direction.

Drilling with a drill or ratchet is slow and requires a lot of effort. In this regard, electric and pneumatic drills are widely used.

Pneumatic drill.

Pneumatic drill working compressed air pressure of 5 - 6 at. Pneumatic drills work well when drilling small holes. Air is supplied by a hose to the shank of the drill handle. Through the valve, air enters the stator, acts on the rotor blades and imparts rotation to the rotor. The rotation from the rotor through the gearbox is transmitted to the spindle with the drill chuck.

Electric drill.

Electric drills have the following advantages over pneumatic drills. They are relatively light in weight and are equipped with strong drives in the form of electric motors, which protects them from overload. For installation work especially suitable are electric drills with a single-phase electric motor, which is equipped with a collector.

Types of drilling machines.

In the boiler industry are widely used:

• – vertical drilling single-spindle and multi-spindle machines;
• – horizontal drilling single-spindle and multi-spindle;
• – special drilling machines.

Radial drilling machines.

Rice. 7. Radial drilling machine.

1 - bed; 2 - column; 3 - traverse; 4 - caliper with an electric motor; 5 - table.

Of the vertical drilling machines, the most widely used are radial drilling machines (Fig. 7). They are very convenient when drilling parts with numerous holes located on various distances from each other. Radial drilling machines are manufactured with 180 and 360° swivel arms.

Vertical drilling machines (Fig. 8) are built with a free standing stand. Radial drilling machines with a 360° swivel arm have a rotating column, with long distance between its supports. Therefore, the rotation of the rotating column is easy and smooth. In addition, a very stable shoulder position is achieved when drilling. In all types of radial machines, the movement of the arm up and down comes from an electric motor, from which the machine spindle also receives rotation. The motor shaft is located vertically and directly meshes with the gear enumeration of the machine.

Rice. 8. Vertical drilling machine.

Radial drilling machine appointment.

Radial drilling machines are used for drilling tube sheets, boiler sheets and other parts. For drilling holes on curved surfaces, the spindle head has the ability to rotate along the curve.

The drill in the spindle of the drilling machine is attached with a conical part (tail). Each drill diameter corresponds to a specific Morse taper size. Morse cones are made in five numbers from 1 to 5. For drills with a diameter of up to 15 mm, Morse cone No. 1 is used, for drills up to 23 mm - No. 2, up to 32 mm - No. 3, up to 50 mm - No. 4, up to 80 mm - No. 5. If you need to drill a hole with a drill having a cone No. 1 in a machine with a cone No. 4, then adapter bushings are used for this so that the bushing has an outer cone No. 4.

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, for repairs interior spaces do not use industrial drills (it 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 you have to work 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 next rule: The thinner the drill, the more drilling speed is required.

In addition, it is important to ensure that the handle is securely attached to the shaft. hand drill. 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 hard metals like copper or aluminum, but for something harder (for example, for stainless steel), you need to take products from titanium carbide or chrome-vanadium alloy.

Separately, we should talk about optimal speeds. Common mistake novice masters is to use too many revolutions. 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 highlighted. 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 do without conventional 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 a variety of 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 puncher (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 enough solid material Therefore, drilling it is very, very difficult. Besides, cast iron products 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 standard timber 18 cm thick, it would be best to take a drill with a diameter of 25 mm and a length of 36 cm. It will be necessary 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 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)

Enough 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.

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 during repairs 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 kind of tool is needed for each type of work so that the holes are the right diameter and in a strictly intended place, and what safety measures will help to avoid injury.

Tools, fixtures, drills

The main tools for drilling are manual and electric drills, and, if possible, drilling machines. The working body of these mechanisms - the 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 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 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, usually with a 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.

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

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 business. 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), you will need hollow bi-metal hole saws or hole saws with carbide teeth with center drill. Moreover, the craftsmen traditionally recommend Bosch in this case, especially on hard metal, for example, 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 when in large numbers 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 machine oil, can be used, and boil the solution until a soapy homogeneous emulsion is obtained. Some masters use lard to reduce friction.

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 can be recommended to purchase a special machine with automatic coolant supply 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.