Correct sharpening of a drill for wood. drill levis. cutting spiral on wood. sharpen a drill for wood: work flow chart

Varieties of drills for wood

Usually, quality drills are used by experienced craftsmen who require different types of products in their work to create holes in wood. These can be holes, for example, for spikes, bolts or pins. Moreover, the drilling process itself can be very diverse in quality, which will carry with it thoughts about how to properly sharpen the drill after operation and whether it will have to be sharpened at all.

The most common types of drills today are: screw, spiral, feather, center, ring and Forstner drills.

Screw

If you need to drill a tree across the fibers, without wondering once again how to sharpen a drill on a tree, then a twist drill with a fine thread at the end will come in handy. They can be up to 50 millimeters in diameter. A special screw shape will help to remove chips from the place of work in time and thereby not overheat the rod. Depending on the required hole depth, drills longer than a centimeter can be purchased, with a minimum size of 400 millimeters.

Twist drills for wood

Spiral

The spiral product is immediately recognizable by the perfectly ground milled spiral with a sharp point to prevent any lateral movement of the rod during operation. It is thanks to the spiral shape that holes are easily drilled in veneer structures. The corresponding drills reach 52 millimeters in diameter, and the smallest can be found at 3 millimeters. To accurately aim at the intended drilling site, the tail of the product is equipped with a conical shape, which gives a lot of convenience.

If, when purchasing, the choice fell on twist drills, then you should always remember about the relationship between the diameter of the product and the maximum number of revolutions that it can produce. Otherwise, the service life of the product will be drastically reduced. If you need to machine hard wood surfaces, it is best to set a maximum of 900 rpm with a drill diameter of 14 millimeters or less. But for soft wood, you can set 1800 revolutions on the drilling tool.

Twist drill bit set for wood

Perovs

The most common type of drill is a feather drill. It is it that suggests how to sharpen a feather drill for wood, and is most often used in repair and construction work. It is the most convenient and has various diameters.

It has only one important drawback: this shape of the drill does not contribute to chip evacuation and the drilling process becomes much more complicated, especially when a hole with a great depth is required. That is why experts recommend using this type of drill when working with wood-based panels or thick boards, where the drilling process will take place as efficiently as possible.

A special type of tip for a feather drill or a similar product with an extension can correct the situation. Such an extension has a hexagonal shape, and may well be used for other types of drills. In this case, the diameter of the final hole can reach up to 52 millimeters.

Drill bits for wood

Center and ring

But center drills are useful for creating perfectly even through holes in a wooden surface. Typically, such products are in the form of a 50 mm (minimum - 12 mm) rod with a cutting edge at the bottom, reaching a length of up to 150 millimeters. Of course, you won't be able to make holes deep enough.Hole drills that look similar to a crown or ring with teeth are suitable for this. They are usually sold as a complete set of bits with a center drill and a single base.

Forstner drills

When it comes to renovating or creating furniture, rather than thinking about how to sharpen a feather drill on wood, then you can immediately go for the Forstner drills that are best suited for this business. They allow you to drill completely blind holes with a perfectly flat bottom. In this case, the diameter of the product reaches from 10 to 50 millimeters. The drill itself is coated with a specialized alloy that protects and increases the service life.

Drill for wood Forstner

Features of use

Among the advantages of Lewis drills, it should be noted:

  1. Smooth workload build-up as the tool deepens into the material.
  2. High quality of the inner surface of the hole, since the burrs formed during drilling are completely cut off by the lateral cutting edge and immediately removed by the auger edge of the drill to the outside.
  3. The wide helical flute ensures reliable chip evacuation, regardless of the amount.
  4. The hexagonal tip on the shank provides a secure hold of the drill in the chuck.

High quality and productivity, especially noticeable when making holes of considerable depth, do not cancel some of the limitations of twist drills:

  1. When the Lewis drill gets jammed, which is possible in hardwood operations, it stops almost instantly, and is accompanied by a sharp kickback. This can lead to injury to the worker.
  2. Since the cutting forces in this type of drilling are high, the quality of the material is critical to the durability of the auger drill. Therefore, it is worth purchasing a tool from well-known manufacturers that indicate the grade of steel (the grade is usually not indicated on drills made in China).
  3. The twist drill has increased fragility, since during hardening it is usually annealed throughout the entire section. With a relatively low stiffness, this can cause destruction of the working part.
  4. The cost of Lewis drills is higher than conventional drills with the same hole diameters.
  5. Low-power drills (less than 1000 W), when started, the drill of this design may not turn. It is also important that the drill has a reverse function.

Drill classification

Some types of drills: A - for metal; B - wood; C - for concrete; D - first drill for wood; E - universal drill for metal or concrete; F - for sheet metal; G - universal drill bit for metal, wood or plastic. Shanks: 1, 2 - cylindrical; 3 - SDS-plus; 4 - hexagon; 5 - tetrahedron; 6 - trihedron; 7 - for screwdrivers.


Center drill


Step drill


Hollow drillsBy the design of the working part

there are:

Twist (screw) - these are the most common drills, with a drill diameter from 0.1 to 80 mm and a working part length of up to 275 mm, they are widely used for drilling various materials. 116 ... 118 °; 2φ0 = 70 °; 2φ0 '= 55 °. Thus, the length of the cutting edge is increased and the heat dissipation conditions are improved. A groove is cut into the lintel with a width and depth of 0.15D. The bridge is sharpened at an angle of 25 ° to the drill axis at 1/3 of the cutting edge length. As a result, a positive angle γ≈5 ° is formed.

Flat (feathers ; jarg.feathers ) - used when drilling holes of large diameters and depths. The cutting part is in the form of a plate (blade), which is mounted in a holder or boring bar or is performed in one piece with a shank.

Forstner drills - an improved version of the pen, with additional cutters-milling cutters.

For deep drilling (L≥5D) - extended twist drills with two screw channels for internal coolant supply.The helical channels pass through the drill body or through tubes soldered into grooves milled on the drill back.Designs by Yudovin and Masarnovsky - are distinguished by a large angle of inclination and the shape of a helical groove (ω = 50 ... 65 °). There is no need to pull the drill out of the hole frequently to remove chips, which increases productivity.

One-sided cutting - are used to make precise holes due to the presence of a guide (support) surface (cutting edges are located on one side of the drill axis).Cannon - are a rod, in which the front end is cut in half and forms a channel for the removal of chips. To guide the drill, a hole must first be drilled to a depth of 0.5 ... 0.8D.

Shotguns - used for drilling holes of great depth. They are made from a tube, crimping which, a straight groove for removing chips with an angle of 110 ... 120 ° and a cavity for supplying a coolant are obtained.

Hollow (also annular, crown) - drills that turn only a narrow annular part of the material into chips.

Centering - used for drilling center holes in details.

Stepped - for drilling holes of different diameters in sheet materials with one drill.

By the design of the tail section

there are:

  • with a cylindrical shank (GOST 10902-77, DIN 338)
  • with a tapered shank (GOST 10903-77, DIN 345)
  • with three-, four- and hex shank
  • SDS, SDS +, etc.

By manufacturing method

there are:

  • Whole - twist drills from high-speed steel grades P9, P18, P9K15, P6M5, P6M5K5, or from hard alloy.
  • Welded - twist drills with a diameter of more than 20 mm are often made welded (the tail part is made of carbon, and the working part is made of high-speed steel).
  • Equipped with carbide inserts - there are straight, oblique and helical grooves (including with ω = 60 ° for deep drilling).
  • With replaceable carbide inserts - also called body (the mandrel to which the plates are attached is called the body). Mainly used for drilling holes of 12 mm or more.
  • With replaceable carbide heads - an alternative to body drills.

By appointment

By the shape of the holes to be machined

there are:

  • Cylindrical
  • Conical

By processed material

there are:

  • Universal
  • For processing metals and alloys
  • For processing concrete, brick, stone - has a tip made of hard alloy, designed for drilling hard materials (brick, concrete) with rotary percussion drilling. Drills designed for conventional drills have a cylindrical shank. Rotary hammer drill shank has different configurations: cylindrical shank, SDS-plus, SDS-top, SDS-max, etc.
  • For processing glass, ceramics
  • For wood processing

Selection rules

Finding a quality attachment at an affordable price is not so difficult. If we are talking about trusted companies such as Bosch, Hitachi, then with a high degree of probability the product is of high quality and reliable. To determine the quality of drills of lesser known brands, there are several rules that are easy to check by visual inspection:

Geometric dimensions. The cutting edges must be symmetrical to each other, be of the same size.
Sharpening quality of cutting edges. It is checked by touching it with a finger, similar to checking the sharpness of the blade of a kitchen knife.
The quality of the attachment. Any irregularities in the working or tail section should alert you. For reliable products, the ebb is almost perfect.
Color metal

An important parameter that is paid attention to in the first place:

Steel gray - a high probability of complete lack of processing.

Black - the metal is steam-calcined. This treatment increases the strength and wear resistance of the packing.

Golden - internal stress has been removed from the metal. This greatly increases the strength.

Bright golden - the drill is coated with a thin layer of titanium nitride.It will last a long time, it will cope with the most durable wood.

Using an electric machine

To begin with, it is worth clarifying that this process will be quite difficult for those who have never sharpened before. If you are one of these people, then try to practice and sharpen an already worn-out tool that you have not used for a long time. Only after a little training will you get an idea of ​​how things are with the process. It will be possible to get down to business directly.

The work is painstaking - one extra movement can ruin the instrument, which, of course, you do not need

Therefore, it is very important to follow the instructions below, it will help you to do the procedure in the most correct way.

During execution, you need to be guided by several rules that will ensure you a good outcome:

  • place a container of cold water next to it - it will come in handy for cooling an overheated drill;
  • 45 degrees is the most correct angle. Therefore, try to keep the element in this position;
  • the drill is installed on the edge of the machine disk - this is the most correct option;
  • if you want sharpening to be done as accurately as possible, then place the element in the washer - this way you will be sure that the work will go well;
  • the trailing edges of the drill must be tucked a few millimeters and then monitor their evenness;
  • the jumper of the tool should be thin, this will provide you with the greatest convenience in work;
  • after the process is almost complete, slow down a little the speed of the machine and continue sharpening;
  • after finishing cool the finished item with water, make sure it works properly. If this is not the case, then continue the process until the instrument is in optimum condition.

Simplicity of the device and ample opportunities: ballerina on wood

If it is necessary to make a large-diameter hole in the material, a drill can be used, which in everyday life has received a very euphonious name - ballerina (by the external similarity of the divorced cutting elements of the device with the image of the dancer). Such a device consists of a centering drill and cutters, which move apart along the guide in different directions at the same distance, thereby outlining the dimensions of the diameter of the future hole. Most of the ballerinas have two incisors, but there are models with three.

The principle of operation of this type of drill bit:

  • a central drill makes a hole in the material;
  • the incisors mark a circle line that determines the size of the future groove;
  • manually (using a brace) or using a rotary power tool, the device is set in motion.


Most ballerinas have two or three incisors.

The ballerina can make holes in wood, wood materials, drywall, ceramic tiles, plastic. Such a nozzle is inexpensive and is quite suitable for non-professionals.

We sharpen on a grinder

At home, it will not be difficult on an ordinary grinding machine. The only thing, it is desirable that the machine be equipped with a handyman, i.e. a small platform located in front of the working surface of the grinding wheel. The distance between the handguard and the end of the circle should be no more than one millimeter.

If the tip is very dull, i.e. cutting edges with rear surfaces have become asymmetrical, in order to properly sharpen the tool, it is advisable to make a simple device by following these steps:

  • draw a straight line on the bracing at an angle of 60 degrees with respect to the working surface of the abrasive disc. The line should be opposite the work surface;
  • fasten the piece of metal corner on the handy, aligning it along the marked line, as shown in the photo below. Those. the corner should also be located in relation to the working surface of the circle at an angle of 60 degrees. You can use a clamp to fix the corner.If you will be sharpening often, you can drill holes and fix the corner with bolts.

Thanks to this device, you can attach the drill bit to the back of the corner with your own hands and thus provide a back surface angle of 60 degrees. Now that everything is ready, you can get to work. First of all, you need to install the coarse abrasive disc and turn on the machine. Then you need to correctly pick up the drill. To do this, put two fingers of your right hand on the handcuff, and lay the tool to be sharpened on them. As a result, the fingers will serve as support. With your left hand, grip the shank of the tool to be sharpened. Turn the drill itself so that the cutting edge that you will sharpen is strictly horizontal.

Now attach the tool with the side plane to the back of the corner and bring it with your own hands to the working surface of the sharpener. The right hand should remain stationary, and the left, which holds the tool by the shank, should move slightly in the vertical plane, swinging the drill. Therefore, the sharpening must be from the cutting edge to the end of the flank.

In this pattern, perform several swinging movements with your left hand up / down.

You do not need to strain your hands too much, as the drill will not vomit from you, so just be careful. Having sharpened one back surface, rotate the drill 180 degrees with your left hand and sharpen the second back surface in the same way.

Upon completion of the work, make sure that the angle of the drill sharpening, i.e. the vertex angle is 120 degrees, which is optimal for metal tools. Also, make sure the edges and backrests are symmetrical. If the tool is far from ideal, it still needs to be sharpened.

I must say that as a result of the movement of the shank in the vertical plane, the back surface is rounded. Therefore, such a sharpening is called conical. It is used for drills with a diameter of more than three millimeters. It is even easier to sharpen a thinner drill correctly for metal - its cutting part is pressed against the plane of the sharpener and sharpened without any swaying. As a result, the back surface acquires one flat plane. Therefore, such a sharpening is called single-plane. The grip of the drill with this processing is shown in the photo below.

After the sharpening is completed and the tool acquires the correct shape, you need to fine-tune it. The fact is that the surface after sharpening with a large abrasive is far from ideal. Therefore, you need to install a disc with a fine abrasive on the machine and remove all roughness. As a result, the surface should be perfectly smooth.

To make sure the job is done correctly, try drilling a hole, maybe not even deep, and make sure the edge is smooth and straight. This is the main indicator of a sharpened tool.

Drills for wood are also sharpened absolutely. The only thing is that their apex angle becomes sharper - 140 degrees. Accordingly, the tool is brought up to the sharpener at an angle of 70 degrees.

Application of special equipment

It should be borne in mind that it is impossible to sharpen the drill without special equipment. This is due to the unusual configuration of the cutting edge. As a rule, a special machine is used for sharpening. While sharpening the surface, the metal may become hot. That is why it is necessary to provide for the possibility of timely surface cooling.

A device for sharpening drills at home.

Note! In the absence of the required machine, sharpening can be done with an ordinary file. However, a regular file will not allow you to get the job done quickly.

It should be borne in mind that when you change the shape of the drill, it cannot be used in the future.

Design features and main characteristics

The design of twist drills, which are often called twist drills, consists of the following elements.

Working part

The working part has two grooves located along the helical line. They perform several functions at the same time: they form the cutting part, remove the chips created in the machining zone, and provide coolant supply to the drilling area.

Shank

With this structural element, the tool is fixed in the chuck of the equipment used. The shank can be made with a special foot that makes it easier to remove the tool from the cone-shaped socket, or a driver that is involved in the transmission of torque from the chuck.

Neck

This technological element is responsible for the output when used for tool grinding.

The main parts of the drill

Calibration part

This element looks like a narrow strip that continues the groove on the working part. This guiding part has another common name - "ribbon".

Cutting part

This part is made up of five cutting edges: 2 main, 2 auxiliary, which are located in a spiral along the axis of the drill, and 1 transverse, located at the end of the tool and having the shape of a cone. All of them are formed due to the intersections of the groove surfaces. So, the main cutting edges are the intersection of the front surface of the tool groove with the rear, auxiliary - the front surface of the groove with the surface of the calibration part, transverse - the intersection of the rear surfaces of the ribbons.

Elements of the working part of the drill

The high popularity of twist drills is associated with the following advantages.

  1. Tools of this type are distinguished by a large margin for regrinding the cutting part.
  2. Twist drills with a cylindrical or taper shank are distinguished by the best stability of their position during the drilling process.
  3. Due to the peculiarities of their design, such tools ensure timely removal of chips from the processing area.

The main parameters of spiral drills with cylindrical and tapered shanks, the requirements for which are stipulated by GOST 10902 and GOST 10903-77, are listed in the table.

Table 1. Designation of the main parameters of drills

Geometrical parameters of the cutting part of the drill

The values ​​of all the above parameters are determined by the tasks for the solution of which it is planned to use the tool.

Twist drills are used not only for metal processing, but also for making holes in other materials such as concrete and wood. There are also multipurpose tools. The drills used for processing various materials differ from each other both in shape and design, and in their geometric parameters given in the corresponding GOSTs.

Depending on the configuration of the part clamped in the chuck, drills are distinguished:

  • with a cylindrical shank;
  • with a tapered shank.

To fix twist drills with tapered shanks on the equipment, as indicated by GOST 10903-77, universal adapter sleeves are used, the bore holes in which are made according to the "Morse taper" type. GOST-compliant tools of this type can be used to equip any equipment.

Practical training

If you feel that you are having trouble sharpening the instrument correctly, then you should practice more. This can be done through a lot of practice - take a few drills that you no longer use and try to sharpen them correctly. Through trial and error, you can learn how to perform the procedure perfectly.

Sharpening a tool is not a difficult process, although some people think otherwise. Many Internet resources describe in detail and even show the steps of this process. Here you can watch a video that very accurately shows how exactly you need to sharpen the drill.

The video shows how to sharpen correctly. By following the man's instructions, you will be able to do the job well. The tool should be the same as it was purchased.Only in the case of a correctly performed procedure will you be able to use it in the same way as before.

If you make a mistake, you will have to discard the drill. But everyone is wrong, so do not be upset if you did not succeed in sharpening the tool the first time. Everyone learns from their mistakes. The main thing is not to quit unfulfilled work due to the fact that something is not working out for you.

In order to learn how to perform the action as efficiently as possible, try to get involved in the process as much as possible, to understand how it works. Only competent consideration of every detail can lead you to success.

Drilling

The main elements of the twist drill

Drilling is one of the oldest and most widespread methods of machining holes, although the modern twist drill appeared only in 1825. The shapes and designs of modern tools for machining holes have reached significant development in connection with the numerous technological problems in various branches of mechanical engineering. But the most widely used are twist drills, which are a complex cutting tool operating in more severe conditions compared to a cutter in terms of chip formation and removal, power and temperature stresses, and the convenience of observing the operation of the cutting edge.

The twist drill consists of a working part (cutting and calibrating parts), a neck, a shank and a foot (Fig.11.1, a).

The geometry of the cutting part of the drill (Fig.11.1, 6-d) characterized by the following angles.

Apex angle 2cr form two main cutting edges, it is measured in projection on the main plane. With an increase in this angle, increase

Rice. 11.1. Twist drill:

a - drill design; 6G - geometry of the cutting part of the drill

axial force is generated, and a decrease in it can lead to breakage of the cutting tool.

The following values ​​of the angle at the vertex are taken:

  • 2 (p = 90-I00 0 for processing light alloys;
  • 2ph = 130-I40 0 for processing aluminum alloys;
  • 2 (p = 115-I18 0 for carbon steels;
  • 2ph = 125-N40 0 for heat-resistant steels.

Front corner in section N — N in the normal secant plane is the angle between the tangent to the rake surface at the point of the main cutting edge and the normal at the same point to the circle of rotation around the drill axis. The rake angle decreases to the drill axis and can be negative or equal to zero at the transverse cutting edge, which increases the deformation of the cut chips, friction forces, and, consequently, heat generation in the cutting zone.

Main back angle a - it is the angle between the tangent to the rear surface of the tool at the considered point of the main cutting edge and the cutting plane coinciding with the direction of the relative motion of the cutting edge. For a drill, the direction of the relative velocity is tangent to the helix described by that point on the cutting edge. The clearance angle increases from the periphery to the center of the drill, which has a positive effect on the cutting process. In plane 0—0 the angles y and ω are related. In plane N — N - normal clearance angle a/a... (fig. 11.1.6):

where a = 8-U2 °.

The angle of inclination of the helical groove co - the angle between the axis of the drill and the tangent to the helix along the outer diameter of the drill. With an increase in the angle of inclination, the friction on the front surface and the degree of deformation plasticity decrease. But it is possible to increase the angle of inclination up to a certain limit, ω = 3 (H35, since its further increase can lead to breakage of the drill.

The angle of inclination of the transverse cutting edge y = 5 (H55 °.

Angle of inclination of the cutting edge X Is the angle between the main cutting edge and the perpendicular to the cutting speed vector. Injection X is measured in the cutting plane and takes on the values X = 7-И2 °.

Front surface - the helical surface of the groove, along which the chips come off.

Rear surface - the surface facing the cutting surface.

Main cutting edges - these are the lines formed by the intersection of the front and main back surfaces.

Ribbon - a narrow strip on the cylindrical surface of the drill along the helical groove. The tape provides direction to the drill when cutting, reduces friction against the hole wall and acts as an auxiliary cutting edge.

Transverse cutting edge formed as a result of the intersection of both rear surfaces and is only present on the drill.

2

Twist drills with cylindrical shank are produced in short, medium and long series according to the relevant standards. This variety provides the optimal selection of the right tool for each specific task.

For all drills, center holes are made in accordance with GOST 14034. It is permissible to produce a tool without centering holes. Medium and long series products can be produced with or without a neck according to their standards. Its size is not regulated.

GOST 4010-77 applies to left and right short series drills with a diameter of 0.5–40 mm. According to this standard, depending on the diameter of the produced drill, the length is (mm):

  • the total of the entire instrument is 20-200;
  • working part - 3–100.

GOST 10902-77 applies to left and right medium series drills with a diameter of 0.25–20 mm. Length is (mm):

  • the total of the entire instrument is 19–205;
  • working part - 3–140.

GOST 886-77 applies to long series drills with a diameter of 1–31.5 mm. Length is (mm):

  • the total of the entire instrument is 56–316;
  • working part - 33–207.

For these products, the direction of the spiral is right. The left ones are manufactured by agreement with the customer.

For all this tool, the technical requirements for manufacturing are regulated by GOST 2034-80. According to this document, these drills are made from high-speed steel and are intended for drilling holes in ductile and gray cast irons, alloyed and carbon structural and structural steels of high and increased machinability. This tool is manufactured in 3 classes of accuracy: it is produced in different types and, accordingly, according to different standards. This allows you to optimally select exactly the tool that is best suited for a particular type of work.
There are the following GOSTs:

  • 10903-77 - for drills of normal length;
  • 12121-77 - long;
  • 2092-77 - elongated;
  • 22736-77 - with carbide inserts.

All of these tools can be manufactured with or without a neck according to their standards. Its size is not regulated.

GOST 10903 applies to drills of normal length with a diameter of 5–80 mm, which are produced in two versions: with a normal and reinforced shank. According to GOST 10903, depending on the diameter of the produced drill with a normal shank, the length is (mm):

  • the total of the entire instrument is 133–514;
  • working part - 52–260.

GOST 10903 drills with a reinforced shank are produced with diameters of 12–76 mm. The length of their working part is the same as with a normal shank. The lengths are as follows (mm):

  • total - 199-514;
  • working part - 101–260.

The sizes of the Morse cones used for fastening in the chuck of the machine are from 1 to 6.

GOST 12121 applies to long drills with a diameter of 5-50 mm, which are designed for drilling through special jig bushings. Length is (mm):

  • the total of the entire instrument is 155–470;
  • working part - 74-321.

The dimensions of the Morse cones used for fastening in the chuck of the machine are from 1 to 4. For the tool of these two standards, the direction of the spiral is right. The left ones are manufactured by agreement with the customer.

GOST 2092 applies to elongated drills with a diameter of 6–30 mm. Length is (mm):

For this tool, the technical requirements for manufacturing are regulated by GOST 5756-81. In accordance with it, these drills are designed for drilling various cast iron parts. Classes should be manufactured:

  • increased accuracy - A;
  • normal - V.

Carbide inserts of the VK type should be used as cutting equipment. Product bodies are made of 9XC or alloy.It is allowed to manufacture housings from other brands with a tungsten content up to 6%. Cobalt containing steel alloys must not be used.

A tool with a working part with a diameter of 6 mm and more, the body of which is made of high-speed alloy, must be manufactured welded. Shanks of welded products should be made of steel 45 or 40X. Not allowed in the welding zone: lack of penetration, surface cavities and ring cracks.

Twist drills are among the most versatile and, accordingly, popular tools used to make holes in various materials. Twist drills are regulated by GOST 10902-77 and GOST 10903-77. Based on the provisions of these regulatory documents, as well as the parameters of the hole that you want to create, it is quite easy to choose the right tool.

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