How to sharpen a feather drill. Lewis drill

The Lewis drill is designed to produce deep holes without large diameter in wood of various species with any degree of humidity. The screw-shaped cutting edge of the drill begins with a sharp tip, with the help of which preliminary centering of the future hole is performed. And the spiral itself removes chips from working area.

Design

The Lewis drill is included in the basic tool kit of a professional carpenter, being lightweight, it does not load the motor of an electric drill, and allows you to perform blind and through holes V hard to reach places: corners of beams, places of fastenings wooden parts overlap, etc.

The twist drill consists of the following sections:

A shank that has a hexagonal profile and is designed to fix the drill in a drill chuck or drilling machine.
The main working part, which is a spiral tape of constant cross section and a relatively small angle of inclination. For the Lewis spiral, it is selected in such a way as to ensure reliable removal of chips from the drilling zone.
Centering, ending with a tip with a conical thread, which allows reducing the axial load during the operation. For a tool of relatively low rigidity (and a twist drill is just that), high axial loads become the main cause of failure.

Due to the complexity of the Lewis drill profile along its length, such equipment is almost never manufactured in a welded version. The material is high speed steel grades 10Р6М5, Р6М3 and the like, according to GOST 19265-74.

A special feature of the Lewis spiral is its single-thread nature, which provides the drill with the ability to spontaneously retract into the cavity of the resulting hole. At the same time, the direction of the drill improves, and as the hole deepens, the edge is trimmed to obtain a smooth generatrix.

How does a Lewis drill work?

At the initial moment of drilling, a conical tip is pressed into the material, which, when rotated, is embedded deeper. Then the main, spiral part of the drill rests on it. Unlike other designs of wood drills, the tool in question initially has only one working edge, and then drilling occurs in a spiral cutting part. By increasing the total length of the cutting edge, this helps to reduce the total axial force on the drill, but increases the risk of jamming and “driving” of the drill from the center.

The first problem is solved as follows. Firstly, it is preferable to install a Lewis drill on low-speed, more powerful drills. Secondly, such spiral-like drills are inappropriate to use for making holes in hardwood, since the resulting chips contribute to jamming the waste in a rather long groove. Typically, the number of revolutions is chosen inversely proportional to the diameter of the resulting hole.

To solve the second problem, a twist drill can be used as a reamer, and the preliminary pass, with the exception of particularly deep holes, can be performed using a regular drill. From operating experience it is known that direct production of holes using a Lewis drill is advisable for diameters not exceeding 15...30 mm. In other cases, feather drills are used, and twist drills are used only on the last pass, when it is necessary to increase the smoothness of the side walls.

The moisture content of the wood does not matter when using such a drill, nor does the direction of the wood grain.

Features of use

Among the advantages of Lewis drills it should be noted:

Smooth increase in work load as the tool deepens into the material.
High quality the inner surface of the hole, since the burrs formed during drilling are completely cut off by the side cutting edge and are immediately removed outward by the auger generatrix of the drill.
The wide helical flute ensures reliable removal of chips, regardless of their quantity.
The hexagonal tip on the shank ensures reliable retention of the drill in the chuck.

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

When a Lewis drill jams, which is possible when working with hard wood, it stops almost instantly and is accompanied by a sharp kickback. This could result in injury to the worker.
Since the cutting forces during such drilling are high, the quality of the material is decisive for the durability of the auger drill. Therefore, it is worth purchasing a tool from famous manufacturers indicating the steel grade (the grade is usually not indicated on drills made in China).
A twist drill has increased fragility, since during hardening it is usually calcined over the entire cross-section. With relatively low rigidity, this can cause destruction of the working part.
The cost of Lewis drills is higher than regular ones, with the same diameters of the resulting holes.
Low-power drills (less than 1000 W) may not be able to turn a drill of this design when started. It is also important that the drill has a reverse function.

How to sharpen a Lewis drill?

With a sharp increase in load during drilling, as well as deterioration in the quality of the resulting hole, Lewis drills must be sharpened. It is performed in the following sequence:

When single-plane sharpening, the back angle of the drill is given a value of 28...32º using a file, and they try to maintain this value along the entire length of the screw part. Using grinding wheel the drill cannot be moved. This sharpening is used for small diameter twist drills;
When conical sharpening, which should be done for drills with a diameter of more than 6...8 mm, the tool is placed at the side grinding tool. Hold the tip with your right hand, and the screw part of the drill with your left hand, and as close as possible to the cone. By rocking the tool at an angle of approximately 45º and pressing it against the end, they try to recreate the previous value of the taper when moving from the threaded part to the screw part;
If it was not possible to maintain the required parameters, the Lewis drill can be sharpened. For this purpose, the rake angle is reduced and the width of the cutting band is increased. True, the drill cannot be used with the same efficiency for drilling tough wood with high humidity;
At the final stage, the drill is fine-tuned, which consists of removing all identified marks and nicks, after which the conical thread on the tip is restored.

Working with Lewis drills must be done with some experience, since this design The tool is very sensitive to torques that load the drill.

Any cutting attachments for a drill become dull during operation, which, in fact, does not require proof. However, do not rush to throw them away, since you can return the nozzle to its original functionality by sharpening it. Next we will describe in detail how to do this.

When is sharpening required?

If wood drill bits can be used long time and at the same time remain sharp, then the metal tool becomes unusable very quickly. Of course, an experienced craftsman can identify a dull drill by eye or by its first contact with the metal surface. If you are a beginner, you can determine the need for sharpening of a tool by the following criteria:

during the drilling process, creaking and whistling occur;
the tool heats up much faster than usual;
the quality of the hole is low - there are jagged and burrs;
chips come out of only one spiral groove (this sign may also indicate that correct sharpening).

Keep in mind that if you use a blunt tip you are putting yourself in danger and it may break. In this case, its flying parts can cause serious injury. In addition, the drill can “bite”. In such a situation, if the drill is powerful or you are working on a machine, the part is torn out of your hands, which often also ends in injury. Therefore, under no circumstances should you delay sharpening or replacing the tip.

Main parameters of the part

So that you can properly sharpen the tip, first of all, let's look at its main elements, which include:

cutting part (cutting edge), formed by the convergence of the groove surface and the rear surface;
the front surface, which is located under the cutting edge;
back surface, which is located behind the edge:
a bridge located between two rear surfaces.

During operation of the nozzle, the cutting edge, bridge and rear surfaces suffer the most. Therefore, the restoration of the tool occurs by sharpening the rear surfaces to which the cutting edge and the bridge are adjacent. However, not everything is so simple: in order for the edge to become sharp again and a clear bridge to form, the sharpening angles must correspond to the values from the table:

Compliance with these values will allow the cutting edge to always be the first to contact the surface of the workpiece, which will ensure maximum efficiency tool. The length of the cutting edge depends on the apex angle. Compliance with this will allow the chips to fit well into the groove and come out. If you make the angle more acute, the width of the cut strip will increase, as a result of which the chips will clog the groove and will no longer be removed from the hole with all the ensuing consequences. An angle that is too obtuse will reduce the effectiveness of the drill.

Sharpening on a sharpening machine

At home it will not be difficult to use a regular sharpening machine. The only thing is that it is desirable that the machine be equipped with a tool rest, i.e. a small platform located in front of the working surface of the sharpening disc. The distance between the tool rest and the end of the circle should be no more than one millimeter.

Optimal speed grinding wheel is one and a half thousand revolutions per minute.

If the nozzle is very dull, i.e. the cutting edges with the 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 straight line on the rest at an angle of 60 degrees relative to work surface abrasive disc. The line should be located opposite the working surface;
secure the scrap to the tool rest metal corner, aligning it along the intended line, as shown in the photo below. Those. the corner should also be located at an angle of 60 degrees in relation to the working surface of the circle. You can use a clamp to secure the corner. If you sharpen frequently, you can drill holes and secure the angle with bolts.

Thanks to this device, you can attach a drill to the back of the corner with your own hands and thus ensure 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 pick up the drill correctly. To do this, place two fingers of your right hand on the rest, and place the tool to be sharpened on them. As a result, the fingers will serve as a support. With your left hand, grasp the shank of the tool you are sharpening. Turn the drill itself so that the cutting edge that you will sharpen is strictly horizontal.

Now place the tool with its side plane against the back of the angle and bring it with your hands to the working surface of the sharpener. Right hand should remain motionless, and the left one, which holds the tool by the shank, should move slightly in a vertical plane, rocking the drill. Thus, sharpening should occur from the cutting edge to the end of the flank surface.

During the sharpening process, a large number of sparks, so be sure to wear safety glasses when performing this operation.

Using this pattern, make several rocking movements with your left hand up/down. There is no need to strain your hands too much, as the drill will not be pulled out, so just be careful. Having sharpened one back surface, you should 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 sharpening angle of the drill, i.e. The apex angle is 120 degrees, which is optimal for a metal tool. Also, make sure that the edges and backrests are symmetrical. If the tool is far from ideal, it needs to be sharpened further.

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

After sharpening is completed and the tool has acquired the correct shape, you need to perform fine-tuning. The fact is that the surface after sharpening with a coarse abrasive is far from ideal. Therefore, you need to install a disk with fine abrasive on the machine and remove all roughness. As a result, the surface should be perfectly smooth.

It is necessary to bring the tool to be sharpened to the working surface of the sharpener smoothly so that there is no impact.

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

Drills for wood can also be sharpened in exactly the same way. The only thing is that their angle at the apex is made more acute - 140 degrees. Accordingly, the tool is brought to the sharpener at an angle of 70 degrees.

No sharpening machine - grinder for all occasions

If you don't have sharpening machine, but at the same time you urgently need to sharpen the drill, you can use a grinder (angle grinder). But keep in mind that a sander is one of the most dangerous hand power tools. Violation of safety precautions when working with it leads to serious injuries and sometimes death. Therefore, if you have no experience working with angle grinders, it is better not to try to save money, but to buy a new attachment.

If you nevertheless decide to sharpen drills with a grinder, use exclusively an end grinder for these purposes. petal circle. In addition, it is desirable that the grinder itself be small, i.e. low-power. The sharpening process is as follows:

1. The grinder is placed on a horizontal plane with the disc up so that the disc is also horizontal. The tool must be held firmly with your left hand, and the power button should also be controlled with the same hand.
2. Then the drill must be brought to the disk and sharpened, trying to maintain the factory angles. The grinder should be turned on at minimum speed.

The disadvantage of this method is that sharpening is carried out “by eye”, so if you have not sharpened metal drills before, it is better to abandon this method. Inept actions can further damage the instrument.

We use the device - when theory is not needed

The easiest way to sharpen a drill for wood or metal, which does not require any skills or knowledge from you, is to use a special device for a drill or screwdriver. The device is a nozzle with holes of different diameters.

To sharpen, you need to put the attachment on the power tool, then insert the tool into the hole corresponding to its diameter and turn it until it stops. Special grooves will fix the drill in the working position. Keep in mind that it is extremely important to position the drill correctly in the hole, as only then will the back surface be machined at the correct angle. After installing the drill, you need to turn on the power tool and wait a while until one side is sharpened. Then the tool to be sharpened must be rotated 180 degrees and the procedure repeated.

The disadvantage of the device is that there is a limitation on the diameter. Minimum diameter The drill bit that can be sharpened is 3–3.5 mm, and the maximum is 10 mm. As a rule, the diameter step is 5 mm. However, for domestic purposes this is quite enough. The cost of such a device ranges from 600 to 4000 rubles, depending on the manufacturer. The most expensive products are from German manufacturer Bosch.

A few words about repairing concrete drills

All of the sharpening methods described above apply to tools for metal and wood. However, a drill with a pobedit tip can also become dull. At the same time, it behaves in the same way as a metal tool - it drills poorly, quickly overheats and produces an unpleasant high-frequency sound during operation. It must be said that the principle of sharpening Pobedit drills is approximately the same as for metal tools, however, there are some important nuances.

First of all, you need to measure the height of the cutting part of the dull tool. It makes sense to sharpen drills if the height is at least 7-10 mm. If the height is less, it will not be possible to achieve a high-quality result, so it is more profitable to purchase a new nozzle. For sharpening we need a diamond-coated wheel. Please note that the carbide tip does not tolerate high temperatures. Therefore, it is necessary to work at minimum speed.

To sharpen a carbide drill correctly, you first need to correct the edges of the tip, which are the first to “lick off” when working on concrete. The corners of the soldering edges must be even, i.e. at 90 degrees. Then the back surfaces are sharpened to the soldering point, as shown in the photo above. If carbide brazing ground down to steel, the front part needs to be sharpened. Otherwise, the soft steel will come to the surface of the cutting edge, and accordingly, in this case, no efficiency and quality of drilling will be achieved from the tool.

To sharpen a Pobedit drill without overheating it, use a coolant during work - water or machine oil.

As with any other drill, be sure to ensure symmetry. The cutting sides must be the same size. If the center of the axis moves, the effectiveness of the tool will decrease, in addition, the holes will be uneven. There is also one more important rule– the harder the tip, the sharper the apex angle should be. For Pobedit soldering this angle should be 170 degrees.

That's basically all you need to know to self-sharpening drills

Sharpening a drill at home is not difficult if you know how. The main difficulty in this matter is to withstand correct angles. After all, at home, as a rule, there are no special mandrels and conductors. There is only a sharpening machine. At least, we will proceed from such conditions.

We only have electric equipment grinder. But just because it exists does not mean that you can sharpen drills on it. It is necessary that the sharpening disk has the correct shape - that is, the shape of a cylinder with a smooth, not rounded edge. A convex edge with ground edges may result in incorrect sharpening.

If the disk is very worn out, it is better to replace it with a new one or correct it with a special CBN “pencil”, if you have one on the farm. It is very good if the disk is balanced and does not produce beats or vibrations (in fact, this is a mandatory norm). Only the peripheral surface of the disk is involved in the work, not its ends.

There is a temptation to use the flat side surface of the disk. But after several sharpenings it will lose its shape and fixing the stone after that will be much more difficult.

Sharpening auger for concrete

The hammer drill has a carbide plate as the cutting part, inserted into a slot at the working end and secured with solder. A normally sharpened drill has clear cutting edges with a sharpening angle of about 90 0 and an angle between the edges at the apex of 130–140 0.

With standard sharpening, the front edge of the cutting edge (directed in the direction of rotation) is inclined to the drill axis at an angle of 30 0, and the rear edge is inclined at an angle of 60 0. At manual sharpening, not having special devices, you can focus on the whole, unworn part of the edges and reproduce their angles of inclination.

Sharpening process

We start sharpening from the front edges. We position the drill near the peripheral surface of the stone so that the cutting edge is parallel to the axis of the sharpener and directed upward, and the edge is parallel to the surface, and on a short time Lightly press the drill against the sharpener. A clearly visible mark remains on the metal, which shows whether its position was chosen correctly. The plane of the test section should coincide with the plane of the edge, and the spot of the section should be located in the center of its unworn part, without significant displacement. Finding it empirically correct position, remember it and start sharpening.

Parallelism is not difficult to achieve if you bring the cutting edge to the surface of the stone and navigate along the gap left before contact.

You should not immediately achieve a sharp edge. Remember that you still have to grind down the back edge, and then the edge will “fall into place.”

First, the front edges are sharpened one after another. Then you need to check their symmetry. This is done visually, in the light, by placing the drill head near the edge of an object. The edge should be smooth or concave, but symmetrical. You can make a special template for testing. If there is asymmetry, a shorter edge is additionally ground down.

After this, the back edges of the edges are also ground down one by one, followed by checking for symmetry. The symmetry of the arrangement of the edges is also checked when viewed from the end, along the axis of the drill. When sharpened correctly, they are parallel, and between them there remains a bridge about 0.2–3 mm long, depending on the diameter.

If, as a result of processing, the cutting edges do not become sharp, there are visible roundings or cavities on them, the entire sharpening cycle must be repeated.

Add-ons

When sharpening, it is important not to overheat the tool. To cool, it is periodically dipped in water. A container of water should be kept near the machine. Do not press the drill against the sharpener for a long time. It is better to work with short touches, about 2 – 4 s, with breaks for the same time. In this case, excess heat has time to be removed by the body of the drill and the risk of overheating the edge is reduced.

To work on soft materials without impact, for example on a brick or tiles, the cutting edges are brought “to zero”, without a jumper, and their sharpening angle is reduced to 30–35 0.

How to hold the drill while processing

Since, according to the conditions of the task, we do not have devices for precise positioning of drills, all hope is for own hands. There are a few simple techniques How to achieve a “steady hand”.

It's best if sharpening drills and it can be rested on a tool rest - a special “table” fixed in front of the sharpener. If you cannot achieve the desired position with direct support on the tool rest, you can hold the workpiece in your hands, but be sure to lean on it:

fingers on the rest;
with your wrist or hand on a workbench, on your knee, on any stable and conveniently located object;
elbow or forearm on a workbench or knee.

As a last resort, you can simply press your elbows to your sides, forming a triangle with your arms and torso. But in any case, you need to find a way to hold the tool as tightly as possible with minimal effort.

When fixing the drill during operation, you should remember its position not only visually, but also by the sensations in your hands. Muscular, kinesthetic memory may be more accurate than visual control.

Sharpening a drill for metal

When sharpening drills for metal, only the back surfaces are ground down cutting edges. These surfaces have a rounded shape (with a drill diameter of less than 3 mm - flat) with a decrease relative to the edge of about 10 0. The cutting edges converge to the top of the drill at an angle of 116 - 120 0 (sharpening angle). For brass, copper, soft bronze, this angle is increased to 125–130 0, for aluminum - up to 140 0.

Sharpening

When sharpening, the drill is held with both hands. One near the sharpener, the other by the shank. The fingers of the hand closest to the sharpener (leading) rest on the rest. If it is not there, you need to find any support, as described above.

The drill is positioned at an angle to the working surface whetstone: 60 0 horizontally (half the angle at the apex) and about 10 0 vertically. The sharpened cutting edge is directed upward and located horizontally, parallel to the axis of the stone. The position can be selected when the machine is turned off, according to the shape of the gaps between the edge and the sharpener when viewed from above, and between the sharpener and the back surface when viewed from the side. To more accurately set the sharpening angle, you can clearly mark on the tool rest visible line at the right angle.

When sharpening, the drill is pressed against the sharpener by the cutting edge, and then, without changing the pressure and horizontal angle, it is tilted with the shank down until the back surface is completely processed. In this case, the position of the leading hand does not change. After 1–3 such passes, the drill is rotated around the longitudinal axis by 180 0, and the operation is repeated for the second edge. The tool is rotated only with your fingers, without changing the position of your hands.

After sharpening, you need to check the symmetry of the edges - the equality of their lengths and angles of inclination to the axis of the drill. If one of the edges is shorter, it needs to be sharpened again. The equality of the angles is checked visually - against the light or using a simple template; the length of the edges can be measured with a caliper.

Additional processing

When sharpened correctly, the cutting edges do not meet at the top; a short bridge remains between them. To reduce resistance to entry into the material, the bridge is ground off with the angle of a sharpening stone or a diamond file. Grinding is carried out on both sides, symmetrically, at an acute angle to the axis of the drill, and the edge of the resulting groove is located at an angle of 30 0 to the cutting edge. The purpose of this operation is to shorten the jumper, but not to grind it off completely! Without it, the drill will not be centered upon entry.

The lintel is stitched using drills with a diameter of more than 3 mm. But in practice, for simple work Without high loads, the jumper, as a rule, is not ground down even with a diameter of 10 mm or more.

Checking the sharpness

After sharpening, you need to check the tool in operation and, if necessary, correct it. There are several signs that indicate sharpening errors.

Poor alignment at the entrance; during operation, beating is noticeable - asymmetrical sharpening of edges or bridges.
When working, you can hear the squealing of metal, the drill gets very hot, the chips look like small grains - a large angle of sharpening the edge, insufficient lowering of the back surface (blunt edges).
Increased rotational force, chips quickly form on the cutting edges - the sharpening angle of the edges is too small (excessively sharp edges).

Signs of proper sharpening:

clear centering upon entry, stable work, no beats;
entrance to light material, the chips come out in the form of identical “spirals” from both grooves;
The heating of the drill is low.

Wood drill sharpening

For drilling wood and wood materials There are several types of drills. Here we will consider the most universal and common - spiral.

Features of drilling wood

A twist drill for wood differs little in design from its counterpart for metal. Even the cutting part may be the same. But wood has a fibrous structure. When drilling it, the cutters in different directions interacts with the material differently. The consequence of this may be scuffing and chipping on the surface of the workpiece. To avoid this and get a neat, even hole, use a special sharpening of the drill, with a center and trimmers.

The first to come into contact with the material is the centerpiece - a narrow spike located along the axis of the drill. As it goes deeper, it centers the tool and keeps it from moving laterally. Then the scorers come into play - the side incisors protruding above the cutting edges. They cut wood fibers along the contour of the hole and prevent the spread of flakes beyond its boundaries. The contoured, virtually isolated material is extracted by the main blades.

Geometry of the working part

The angles of inclination of the center faces to the drill axis are 10 0, the inclination of the inner edges of the scorers is 30 0, the outer edges of the scorers coincide with the side surface of the drill. The angle of depression of the rear surface of the cutting edges is 25 0 . The height of the centerpiece and scorers above the cutting edges depends on the diameter of the drill, but the scorers are always lower.

For example, a drill with a diameter of 10 mm should have a center height of 3.5–4.5 mm, and scorers should be 1 mm high. The width of the base of the center is about 1.5 mm. For recommended parameters for different diameters, see Tables 1 and 2 of Appendix 1 to GOST 22053-76.

What to sharpen

To perform such a complex sharpening you need a specially shaped stone. If you have a “pencil” for straightening abrasive discs, you can give a standard sharpening disc a trapezoidal profile (grind one edge to a cone) and use this stone for sharpening only wood drills.

You can also use a grinder disc by installing it on a sharpening machine. For different mounting diameters, an adapter can be ordered. Another option is to use a grinder. But it must be securely fastened.

Sharpening is a familiar job

The process of sharpening a wood drill is, in principle, no different from sharpening other drills. The same techniques are used for selecting the desired angles, fixing the tool and controlling symmetry. If you just need to sharpen a dull drill, then with good equipment there should not be any big difficulties. If you need to make a wood drill from a standard one, then you should first practice on old drills, which you don’t mind using lime for training.

The tool, which is used to make holes in wood, is made of relatively soft metal, but requires sharpening very rarely, however, due to the figured processing, this operation is one of the most difficult. It takes skill to do it.

Types of wood drills

There are several types of such tools:

Spiral;
Serpentine (Levis form);
Feather;
Ring (forstner).

Sharpening methods

They sharpen a part that can be used to drill a hole in wood in different ways:

Manually using a file
On a machine (sharpening machine) powered by electricity.

The nuances of sharpening

To answer the question of how to properly sharpen a drill, you should study what nuances exist for this process. First you need to make sure that the tool is dull. After all, it may be broken or worn out. The following circumstances are considered signs of the need for a sharpening procedure:

Drilling began to take more time;
The hole turns out uneven;
The drill quickly becomes hot and becomes deformed.

Using electric machine who sharpens the tool, you need to use holders for convenience, and also periodically cool the drill in a container with water or machine oil so that it is not subject to overheating and deformation.

The drill must be placed carefully on the sharpening disc. To ensure the most accurate values, you can use additional accessories, for example, a device where a tool is installed and clamped.

This way it will be located in a special mechanism, which will reduce the likelihood of burns due to strong heat during the sharpening process. And to prevent damage to the skin on your hands, you must wear gloves before starting work.

First, preliminary sharpening should be done, and then the edge should be brought to a perfectly smooth shape. For this, the same machine is used, but at low speed. The sharpened drill can then be used again.

An ordinary file can also cope with sharpening this metal tool. However, this procedure will take longer.

It should also be borne in mind that in order to carry out the sharpening process, a person must have good eyesight, and normal lighting must be organized in the room where the work will be carried out.

Actions performed during sharpening

If a person is wondering how to sharpen a drill for wood, then he does not yet have experience in this matter. Therefore, it is better to practice on a tool that is worn out, because improper sharpening will make it impossible to further use or restore it (you will have to throw it away).

To sharpen, follow these steps:

IN mandatory Maintain sharpening angle (45 degrees).
Place the drill on the edge of the sharpening machine.
For greater accuracy, you should place it in a special tool (for example, a washer).
Tuck the rear edges of this tool a few millimeters and make sure that they are even.
When sharpening is completed, it is necessary to reduce the speed of the machine and continue the process.
It is necessary to try to keep the drill bridge thin, this will increase ease of use. There is no need to grind the jumper if the drill itself is very thin.
Then you need to cool the sharpened tool and check how it functions. A straight hole obtained quickly indicates correct sharpening.

Performing the procedure for sharpening a feather drill on wood using a file

If this work is being done for the first time, then you should take a new one feather drill and use it as a sample. After that, you need to clamp the drill that requires sharpening in a vice and use a file to file the sharpening angle of the two cutters, guided by the sample. Then you need to inspect its tip and remove it with the same file exactly in the center without the slightest deviation.

Sharpening on a machine will be similar, only it will take less time, and the drill will have to be cooled several times.

If everything is done correctly, the sharpened tool will last quite a long time.

Drilling wood is one of the most common tasks in repair and construction, but it’s not always possible to purchase a high-quality wood drill. Therefore, it is very important to know how to choose a good tool and be able to sharpen a dull product!

Modern drills are often sold with a set of different drill bits, however, basically, it is always the same type of product, just different lengths and diameter. So you have to choose for yourself types of drills woodworking that meets all your needs. Of course, such a set should include a twist drill for wood; products are presented in a wide range - from 3 to 52 mm in diameter! Good tool this kind should have a point, thanks to which it will not slip off the surface.

Products with a diameter of 10 mm or more must have a hexagonal shank so as not to rotate during operation. It is also important to know what number of revolutions during drilling should correspond to a particular tool diameter. For example, if you are dealing with small products up to 14 mm, you should set no more than 1700-1800 rpm for soft wood and half as much when drilling hard wood. When working with tools with a diameter of 16 to 25 mm, on hard rocks you should stick to 500 revolutions; the speed can be increased three times when drilling soft rocks.

The larger the diameter, the lower the speed - by observing this ratio, you will extend the service life of the product for a long time! When choosing tools, pay attention to the color of the metal - if it is ordinary grey colour, then such a product has not been subjected to any additional processing, accordingly, it will not last long. Black color indicates very hot steam treatment, and yellow inherent in products that are treated with titanium nitride, which increases their service life significantly.

Long wood drills are very dependent on their diameter. You will not find thin and at the same time long products - than thinner tool, the shorter, otherwise it may break even with light pressure. So, a ten-millimeter drill can be up to 45 cm long, while a twelve-millimeter drill can be up to 60! Of course, it is absolutely not necessary to buy such long ones, unless you are dealing with drilling holes in thick beams.

Of course, you must maintain a healthy relationship between the capabilities of the drill itself and the dimensions of the drill, because a product with a length of 45 cm and a diameter of 52 mm will weigh almost 3 kilograms! Regular household drill It will barely crank it even when idling! Experienced builders When working with such “giants”, even low-speed drill-mixers are used!

However, there is a compromise between the ability to drill large diameter holes and the weight of the drill! Products of this type are called feather products, since drilling occurs due to the “feather” required diameter at the end of a long rod. On the market you will find tools from 10 to 55 mm. True, this compromise option also has significant disadvantages compared to the same spiral ones - they do not have a chip outlet, which greatly complicates the process of working with deep holes. Most often, these are used for drilling not very thick boards, as well as fiberboard and chipboard, so they are produced up to 15-20 cm in length. True, there are also extensions with which you can make holes up to 40 cm deep!

Typically, these tools have a hex shank to ensure a firmer fit in the chuck. This option is perfect for holes under door locks. But you can work with them even with not very powerful tools, and they are much cheaper in price than spiral ones - sometimes the difference is 5-10 times! Recommended rotation speed when drilling for hard wood with tools up to 25 mm is 1500 rpm, if drills of a larger diameter are reduced to 1000. Soft wood can be drilled at 1500-2000 rpm.

Forstner drills are especially popular among furniture makers because they can be used to drill blind hole with a flat, even and smooth bottom. That is why such drills are often called plug drills, although in fact this definition does not quite suit them, because there are special products of a different design just for drilling plugs.

The diameter of the products is presented in the range from 10 to 50 mm. Quite often the cutting edges are made of hard alloys, which significantly increases the service life of the product. As a rule, such drills are up to 10 cm in length, although with the help of extensions this parameter can be tripled. In operation, recommended speeds for soft wood range from 2500 rpm to 1000 rpm for large diameters, while hard wood is recommended to be drilled at fairly low speeds. For example, for tools with a diameter of 15 mm, it is recommended to set no more than 500 rpm.

The external resemblance to a crown gave rise to another name for such products - crowns. Their most important advantage is the ability to make holes of large diameters that cannot be made even with the largest twist or feather drills. The crowns look like a ring with teeth and are usually sold in sets, like attachments on one base, inside of which there is a centering drill. Of course, you can’t make very deep holes like this - ordinary models are capable of cutting through material up to 22 mm, professional ones - up to 64 mm. In addition, such tools are effective when working with plastic and drywall.

It wouldn't hurt to note one more thing unusual look– thermite drills, or, as they are called in professional language, milling drills. Thanks to the characteristic appearance Such products cannot be confused with anything else - they have a monolithic tip, like a conventional twist drill, and a core with many cutting edges. With the help of such tools, not only drilling is performed, but also milling - first we drill, and then we go in the right direction. Work milling products Can be done both on wood and plastic. Their diameter does not exceed 12 mm.