Homemade machine for sharpening drills with your own hands. Drawing fixture for sharpening drills. Screwdriver tool
One of the main parameters of a twist drill is the angle at the top, which for strong metals(steel, cast iron, hard bronze, titanium, etc.) is approximately 120 degrees.
The deviation of this angle up or down from the nominal value makes it difficult efficient work drill. In the first case, productivity drops and the tool overheats, in the second, the drill can simply break, unable to withstand the excessive load.
In order to comply with the sharpening parameters without special devices, it is necessary to be highly qualified and experienced as a tool sharpener. Well, for a non-specialist, especially in living conditions, it would be almost impossible to do so.
But with some tools and simple materials, you can make not very complicated, but reliable fixture for sharpening the corner at the tip of a twist drill for hard metal.
What you may need to work on the device
This will require the following tools:- calipers;
- marker;
- vice for metal;
- Bulgarian;
- pliers;
- welding machine;
- grinder with emery wheel.
- a regular hex nut;
- castellated nut;
- a bolt of the same size and thread as the nuts;
- twist drill requiring sharpening.
Manufacturing process
A feature of a hex nut is that any two adjacent faces of it converge at an angle of 120 degrees. Approximately the same size angle at the top of a twist drill for working in hard metals. This random match can be used to make a twist drill sharpener.
To do this, with the help of a caliper and a marker on the nut, we outline the cut lines to get a triangular slot, symmetrical with respect to the diagonal connecting the two opposite angles nuts. The drill will be longitudinally laid in it before the sharpening process.
To cut out the intended triangular groove in the nut, it is clamped in a vise and the grinder makes cuts along pre-drawn lines. You can use pliers to remove the sawn off pieces of the nut.
Next, a castellated nut is taken and its base is welded to the first nut from the side of the cut groove. Moreover, it is necessary to observe their absolute alignment, because when drills of small diameter are sharpened, the bolt, having passed through the castellated nut, will begin to be screwed into the lower nut in order to firmly clamp the drill in its groove.
Now we screw the corresponding bolt into the slotted nut, which will securely press the drill, which is laid in the groove for sharpening on the emery of the grinding machine.
It remains only to sharpen the drill on an emery wheel, using the edges of the lower nut as a template.
To do this, we simply grind the protruding part of the drill flush with the edges of the nut, which even a first-year vocational school student can easily cope with.
After sharpening is completed, the bolt is loosened, the drill is removed from the homemade fixture and can be used for its intended purpose.
Additions and improvements
In the process of welding nuts, splashes of liquid metal can get on the threads of slotted and ordinary nuts. To eliminate this trouble, it is necessary to screw a bolt into them and, thereby, protect the thread.Since one fixture will not be able to cover all the drills in diameter, at least two template clamps will be required: one for small drills, the other for large products. Accordingly, in the first case, the nuts will be small in size, and in the second - large.
The technological process of mechanical processing of materials includes many different operations, which require high-quality and sharp tools. So, in a mechanical workshop at any machine-building enterprise, a set of turning, milling, drilling and more complex machines can be used. They use their own type of tool, for each of which there is a specific method of sharpening.
Features of the drills
Machining of metal is associated with huge loads on the tool. In general, it consists of three main parts: connecting, body and cutting. So the cutting part is a small wedge-shaped element designed to penetrate the metal and remove part of it from the workpiece.
If, for example, everything is clear in a turning tool or a disk cutter with the shape and design of the cutting part, then when processing holes on a drilling machine, everything is much more interesting and complicated, so you need to know how to sharpen the drill correctly. This is a tool designed for axial metal processing. That is, the feed movement is directed strictly along the axis. This should be considered before sharpening the drill for metal, because the wrong cutting angle will lead to vibration and breakage.
The main elements of the cutting part of the drill
Before sharpening a drill for metal, you should familiarize yourself with the design of its cutting part, which includes the following elements:
1. Main cutting edge.
2. Auxiliary helical cutting edge (ribbon).
3. Jumper.
4. Front surface.
5. Back surface.
What is needed for sharpening?
At the enterprise, everything necessary for the restoration of the instrument is always at hand. But the home master has to look for an alternative to high-quality factory fixtures in more simple solutions that can be used in a conventional garage. And yet, before sharpening a drill for metal, stock up on a minimum set:
1. Grinding wheel. It must be mounted on a rotating shaft. The device is popularly known as "emery". Very common in the garage.
2. Capacity for coolant.
3. Coolant (water or machine oil).
In order to withstand the angle of sharpening the drill, such a set may not be enough. After all, you will have to control the process "by eye", which is unlikely to work out without some experience. In this case, the basic kit also needs to include a tool for sharpening the drill, which you can buy or make yourself.
Controlled parameters
When everything is ready, you need to familiarize yourself with some theory in order to have an idea about the main parameters of the axial cutting tool. Before you sharpen the drill correctly, you need to know its angles:
1. Front. Defined in the main cutting plane (running perpendicular to the main cutting edge) as the angle between the rake face and the main plane (perpendicular to the cutting speed vector). It is directed tangentially to the circle of the drill.
2. Rear. Also defined in the principal cutting plane as the angle between the flank and the cutting plane (passes through the velocity vector and cutting edge).
3. Corner at the top located between the two main cutting edges when viewed from the side of the drill.
The optimal value of the front angle is 18-20 degrees, the rear one is 10-12. The corner at the top in drills for metal has a standard value of 118 degrees.
Sharpening process
Now let's talk about how to sharpen a metal drill on ordinary sandpaper. The main sharpening of this axial tool is carried out on the rear surface. To do this, turn on the emery, firmly take the drill in your hand so that the main cutting edge is directed towards the rotation of the grindstone. Now we bring the edge to the grindstone, after which we turn the drill by the shank so that the cutting edge is parallel to the surface of the circle. We do the same operation with the second cutting edge. The result is the so-called simple sharpening of the drill, which is optimal for most metal processing modes.
Simple sharpening is used for drills up to 10 mm in diameter. By increasing this parameter, you can additionally perform a subpoint of the front surface. As a result rake angle decreases, which means that the thickness of the blade (the so-called angle of the cutting edge) increases and, accordingly, the period of durability of the drill.
Sharpening with a fixture or machine
The method described above can be called artisanal, since it is simply impossible to achieve precise control of the drill parameters directly during sharpening. IN best case you will check the angles after the end of sharpening, and at worst, just check how much better the drill has become. And how to sharpen a drill?
Of course, for this it is better to use more advanced options that will allow you to tune in to certain angles in advance. In this case, you will need a device or machine for sharpening drills.
If the scale of work in your workshop is large enough, and regrinding of the tool is required constantly, then purchasing a machine will be optimal. It will greatly simplify the process, especially if you need to regrind carbide drills for metal. The main advantage of its use is the exact observance of predetermined parameters. At large volume work, it is unacceptable to use an incorrectly sharpened tool, as this will lead to a decrease in productivity. Modern grinding machines allow you to get Various types drill sharpening:
1. X-type. Mainly used for drilling in blind holes. Designed to reduce axial cutting force.
2. XR type. Used for universal drills. Cutting into the material is somewhat worse than in the first type, however, such drills have increased strength and durability.
3. S-type. The subpoint described above is used here, which also allows you to increase the life of the drill when machining. various materials(from cast iron to stainless steel).
4. N-type. A subpoint is also used, but of a smaller size. Drills with this sharpening are used for deep drilling.
Fixture design
As it has already become clear, manual sharpening of a drill is the business of a professional who not only knows the correct angles, but also feels the cutting process. Unfortunately, such a flair comes only after many years of practice with a drilling machine or drill. You should not experiment, as you can make your own or purchase a sharpening device. In both cases, it will include the same structural elements and work on the same principle.
So, the main task of the fixture is the correct orientation of the drill relative to the plane of the grinding wheel. To do this, its design includes a base plate, on which it is desirable to place both the device itself and the electric motor, on the shaft of which the grindstone is located. There is also a rotary column on the plate, on which the drill is fixed. It should be able not only to rotate, but also to move towards the grinding wheel.
As a column, you can use any bearing assembly with a shaft, for example, from old drill. A drill bed is fitted on the shaft rings (you can use an adapter sleeve), to which it is pressed with screws. After fixing the drill, the grinder drive is turned on, the column is brought to the grinding surface and rotated to give the back surface of the drill the correct shape. It is important that during the initial setting of the fixture, the angle at the top of the drill is 118 degrees.
Sharpening nozzles
Another simple and convenient way involves the use of such a device as a nozzle for sharpening drills. Its main advantage lies in its versatility and ease of use. The device has a cylindrical shape. On the one hand, there is a connecting node, through which the nozzle is installed on the drill spindle. On the other side there are holes for installing drills of a certain diameter. For sharpening, the drill is inserted into the hole, after which the sharpening mechanism is driven by the drill motor.
Security measures
The sharpening of the drill is associated with the formation of small particles that break away from the sharpener during wear. They heat up and scatter in different directions in the form of fiery sparks, so for safety it is worth using goggles and gloves.
When sharpening a drill without a tool, make sure to securely fix its position. Otherwise, upon contact with the sharpener, it can simply be pulled out of your hands.
When working with hard workpieces, the working surface of the drill wears out quickly. A dull drill gets very hot and loses its strength. This is due to the "release" of the metal. The tool needs to be sharpened periodically. However, this does not only apply to drills.
Drills are inexpensive devices. In any case, those models that are used in household. However, buying a new tip every time it becomes dull is wasteful.
There are factory sharpening devices, but this violates the concept economical use home tools.
Wood drills practically do not become dull, except that the tool can be “driven” at high speeds in a resinous workpiece. Pobedite tips and stone are not sharpened. It remains to sharpen the drill for metal. Many experienced locksmiths carry out this procedure, without any devices.
However, the accuracy of the work leaves much to be desired, and not everyone has an eye home master developed so professionally. In any case, minimal mechanization is necessary.
How to make a homemade tool for sharpening drills?
First of all, it is necessary to acquire a means of control. No matter how you sharpen the drill, you need a template to check the accuracy of the work.
Conventional drills for working with ferrous metals have an edge angle of 115-120 degrees. If you have to work with different materials- read the table of angles:
| Processed material | sharpening angle |
| Steel, cast iron, carbide bronze | 115-120 |
| Brass alloys, soft bronze | 125-135 |
| red copper | 125 |
| Aluminum and soft alloys based on it | 135 |
| Ceramics, granite | 135 |
| Wood of any species | 135 |
| Magnesium and alloys based on it | 85 |
| Silumin | 90-100 |
| Plastic, textolite | 90-100 |
Knowing these values, you can prepare several templates, and in accordance with them, sharpen yourself. In this case, you can use the same drill for different workpieces, you just need to change the angle of the top of the working area.
When working with hard workpieces, the working surface of the drill wears out quickly. A dull drill gets very hot and loses its strength. This is due to the "release" of the metal. The tool needs to be sharpened periodically. However, this does not only apply to drills.
Drills are inexpensive devices. In any case, those models that are used in the household. However, buying a new tip every time it becomes dull is wasteful.
There are factory-made sharpeners, but this violates the concept of economical use of home tools.
Wood drills practically do not become dull, except that the tool can be “driven” at high speeds in a resinous workpiece. Pobedite tips for concrete and stone are not sharpened. It remains to sharpen the drill for metal. Many experienced locksmiths carry out this procedure with their own hands, without any tools.
However, the accuracy of the work leaves much to be desired, and not every home master's eye is developed so professionally. In any case, minimal mechanization is necessary.
IMPORTANT! Sharpen tips with a file, needle file, and even sandpaper- it's pointless. To do this, you need an electric emery (grindstone).
How to make a homemade tool for sharpening drills?
First of all, it is necessary to acquire a means of control. No matter how you sharpen the drill, you need a template to check the accuracy of the work.
Conventional drills for working with ferrous metals have an edge angle of 115-120 degrees. If you have to work with different materials, check out the table of angles:
Workpiece material sharpening angle Steel, cast iron, carbide bronze 115-120 Brass alloys, soft bronze 125-135 Red copper 125 Aluminum and soft alloys based on it 135 Ceramics, granite 135 Wood of any species 135 Magnesium and alloys based on it 85 Silumin 90- 100 Plastic, textolite 90-100
Knowing these values, you can prepare several templates, and in accordance with them, sharpen yourself. In this case, you can use the same drill for different workpieces, you just need to change the angle of the top of the working area.
The simplest, but very effective tool for sharpening - bushings different diameter fixed on some basis.
Schematic drawing of the device in the illustration:
IMPORTANT! The tool in the sleeve should not hang out, an error of only one degree will reduce the quality of drilling.
It is best to make a whole clip of copper or aluminum tubes, under typical dimensions drills Or drill in a bar of soft material enough holes. The main thing is to install a convenient handpiece on your sharpener, which will allow you to right angle move the sharpening device, and serve as a reliable stop.
Our grandfathers used this method. Only as a material for the manufacture of a grinding machine - a corner, an oak bar was used.
In principle, it was enough to place a table or workbench opposite the side surface of the emery - and grinding machine ready. At the same time, the quality and accuracy of processing was high level.
There are different drawings of sharpening devices.
You can use ready-made, or develop it yourself. The main thing is to understand the principle of working with a drill.
IMPORTANT! When working on a grinder, do not allow the drill to rotate around its axis.
If the tool turns at least a millimeter, it will be damaged, and you will have to grind a certain distance for re-processing.
After finishing sharpening, let the drill cool down and take measurements using a template. Both edges must be symmetrical to the nearest tenth of a millimeter. This is especially important for small diameter drills.
The diagram shows typical mistakes self-sharpening:
The design of a grinding machine for twist drills for metal, made from improvised materials
As a basis, a household grinding machine with a proud inscription "made in Germany" is taken, which has all the signs of a product from the Middle Kingdom. Nevertheless, it works properly, there is no axle beating, it keeps the speed under load.
The terms of reference are as follows:
- the handpiece must be strictly on the same horizontal line (or above it) with the axis of rotation of the emery;
- the design is strong and reliable, ensuring the safety of work;
- should be possible as manual sharpening, and semi-automatic - with the help of a device;
- the shape of the handpiece allows you to freely lower the drill shank to the required angle.
No scarce parts are required for the manufacture of the device. All the materials were actually lying underfoot in the barn. The processing of blanks was carried out by a grinder, the same upgraded sharpener, and welding.
Since the emphasis was supposed to be swinging (for semi-automatic mode), a loop connection was made. The holes of the tube, bracket and bolt are matched exactly to avoid backlash. The resulting device has two degrees of freedom.
The platform can be rotated along the vertical axis - changing the angle of sharpening the drill. This axle is fixed. Also, the arm rest can swing, leaning on a horizontal axis, providing correct articulation during sharpening. This degree of freedom is not fixed.
For the base plate, metal 4 mm thick was chosen, the remaining structural elements - 3 mm. The strength is more than sufficient. The handpiece is rigidly connected to the body of the emery. Of course, it is unacceptable to attach it to the protective casing, so we fasten the bracket with the help of an additional metal “cheek”.
The actual guide plate for drills is screwed to the handpiece (more precisely, to the base plate). The plate is 5 mm thick, it has a triangular groove for fixing the drill during processing.
The angle of rotation of the structure is 90 degrees. This will ensure sharpening in any way, from the Leontiev method to pressing at one angle with the development of an acute edge angle due to the curvature of the emery.
The drill being machined is not only firmly held in the groove - it can be freely fed to the abrasive along the groove, without the slightest deviation of the sharpening angle.
Due to some excess of the plane of the base plate above the axis of rotation of the disk, the optimal shape of the sharpening of the back of the head of the working edge has been achieved.
Before starting work, we press the drill against the plate and set the cutting edge parallel to the plate. This completes the adjustment and you can feed the tool to the emery. Sharpening a drill requires certain skills, do everything slowly, carefully monitor the sharpening angle.
The accuracy of the work is the highest, the template is actually not required. It takes some time to install the fixture and adjust the angle, but you can quickly sharpen a couple of dozen drills without spending any effort.
If it is necessary to sharpen a drill with a carbide tip, the oscillating plate can be fixed at a fixed angle. To do this, you just need to put a couple of washers under the axle nut.
A few words about the emery wheel
Usually, for universal tasks, a white circle of electrocorundum is used in a home grinder. It sharpens knives, axes and shovels very well. With it, you can quickly process metal workpieces.
When sharpening carbide drills (and high-speed metal also requires a harder disk), a green silicon carbide abrasive wheel is used. Such circles are marked 64C.
Grit for household work is usually selected 25H.
When sharpening drills, a smaller fraction is required, it is better to work in the range 8H - 16H. It must be remembered that silicon carbide emery gets very hot during operation. Therefore, you can not keep the drill in contact with the abrasive for a long time. After 2-3 approaches, let the metal cool. Best of all, cool it with baking soda water.
IMPORTANT! The direction of rotation of the abrasive determines the quality of the edge. The working surface of the disk should run into the cut, that is, move from top to bottom.
The peripheral surface of the emery, as the main processing surface, must be perfectly flat. You can edit it with an elbor nozzle. For discs of small diameter, it is quite possible to get by with pliers in which the CBN cutter is held.
If we talk about those drills that are used by craftsmen at home, then their cost in stores is low. But even in this case, you should not use them as consumable for single use. After all, updating the drill to the best working condition will not be difficult if the master has the skill or special tools.
There are factory machines that are intended for sharpening, but this is a separate expense item, so most often craftsmen create such devices with their own hands.
Drills for metal create the most problems, and wooden blanks do not reduce the sharpness of the cutting edges so quickly.
To make a machine for restoring the sharpness of cutting elements, necessary funds control (template) that is used to verify the instrument.
Usually tools for ferrous metal, carbide bronze, steel or cast iron - with an edge angle of 115-125 degrees. The length of the other material, these parameters are different.
for soft bronze, red copper - 125, for brass alloys - 135;
for aluminum and soft aluminum alloys, granite, ceramics and wood - 135 degrees;
for magnesium and its alloys - 85 degrees;
for plastic, textolite and silumin - from 90 to 100 degrees.
Wizards, if necessary, make templates according to the above data. By the way, theoretically a single copy of the drill can be suitable for all these metals and other materials, if each time you sharpen different working surfaces.
An elementary handicraft fixture that is often used, bushings attached to the base. There are many drawings on the Internet for self-manufacturing. It should be noted that the tool must be well clamped, the accuracy depends on 1 degree.
If desired, you can make a significant size clip using aluminum or copper tubes correlative with the typical characteristics of drills or drill many holes in a soft metal workpiece. It is necessary that the sharpener has a comfortable hand rest to move the device and hold the stop.
This primitive sharpening machine is easy to install on a workbench or table.
Practical example of working with a drawing
The essence of the problem: there are drills, they need to be sharpened.
We will use one of the sharpening methods, close to the factory ones. Too lazy to catch hands. Better monkey way - put it and you're done. It took about 1 hour to make the fixture according to the finished drawing.
A little welding work by template. A corner has been made. Put on the puck, it's just pressed on.
Let's try the first sharpenings, if everything is assembled correctly, we will refine and cultivate, make a quick adaptation.
After sharpening the drill, we carry out a test. Two casting chips are visible, which means that the sharpening was carried out correctly.
The only drawback is that one chip is longer than the other, which means they missed the length of the edges. It is necessary to make an emphasis, which will regulate the length, ensure the symmetry of the edges. To do this, we will make a thrust washer, which will be exposed and machined. Or we cut it so that it becomes possible to process shorter drills. 
