What to make a punch yourself from. Simple valve core

If among professionals anyone called this tool a core, it ceased to be such by definition. A core or core is a hole in the material - the result of the work of the punch and nothing else. And also a sample of soil rock obtained in a special way, but this is definitely not the subject of our article. Now, even Wikipedia presents the word “kern” as the second name for the instrument - puncher, which is fundamentally wrong, but let’s leave this to the conscience of the authors of the material.

The center punch is a metal rod made of tool steel with a sharpened striking part, sharpened at an angle of predominantly 120° and hardened to a length of 20 - 30 mm, and a striker on the other side, also heat-treated, but 10 - 15 mm. It is also called the butt plate. Used in metalworking to obtain holes or cores necessary for the convenience of drilling material.

Most of the tool remains unhardened, and therefore less fragile, which is done primarily for the purpose of safety of its use. The cross-sectional shape of the punch rod does not play a special role: it can be round, and then it is often knurled to make it more convenient to hold it in the hand, or maybe hexagonal. The material of the hexagons is carbon steel, amenable to heat treatment, therefore, if you need to quickly make a center punch at home and find a hexagon with a suitable cross-section, you can safely use it - it will accept hardening without carburization (saturation of the surface layer of steel with carbon).

Punching, in almost all cases, is carried out for subsequent drilling of the material, so that the drill does not slide along the surface of the workpiece at the initial stage of drilling. But there are also options...

Depending on the diameter of the drill, the dimensions of the punch are selected, but this more often happens in production during mass punching to produce holes of different diameters.

Also, the sharpening angle of the punch may be different, because for soft metals the drill is sharpened at a smaller angle.

Techniques for working with a center punch

There are only two ways of punching: one is correct, the second is incorrect.

For core you need:

1. Align the tip of the striking part with the intersection of the marking lines;
2. Place the punch strictly perpendicular to the surface of the workpiece;
3. Apply one confident, accurate blow to the striker with a hammer, trying to ensure that the vector of the blow coincides with the axis of the punch.

That's all, failure to follow these rules will lead to a violation of the accuracy of the core or the shape of the hole, which may cause the drill to move away.

If you made a mistake when punching, then do what no plumbing textbook will advise you to do:

1. Gently, with light blows of a hammer, bring the edges of the core funnel down to the level of the workpiece; if necessary, treat this area with emery cloth mounted on a flat block;
2. Resume the marking lines;
3. Take a punch of a smaller diameter with a sharpening angle of about 60° (for such cases you need to keep it in your home workshop);
4. Perform the punching procedure with extreme care, but with less impact force;
5. After making sure the location of the new core is accurate, take a standard punch and, aligning its tip with the new hole, perform the core with one strong blow.

Types of center punches - photos

In addition to the manual version of this tool, there are other varieties of it.

1. Center punch compass, in addition to clear core punching along the circumference from a given (and cored) center, it allows core punching at a predetermined distance from the edge of the workpiece, which is convenient if there should be a lot of such cores. In addition, the leg can be replaced with a simple extension device and, again, set aside the required distance from the edge, reducing the number of marking lines.
2. Kerner bell Designed primarily for punching spherical surfaces. Installed on the ball, it will flawlessly self-install on its top, which is why it is also called a center finder. The base line can be a circle drawn along its skirt. Also, using a center finder, it is easy to core the centers of the ends of cylindrical figures, of course, if the diameters are suitable.
3. Mechanical spring punch allows you to punch with one hand, it is only important to install it strictly perpendicular and not change this position when pressing. Among its advantages is also the same depth of the obtained cores. And the ability to adjust the force makes it possible to work even with fragile or soft materials without fear of damaging them.

The factor of obvious increase in the speed of core punching is also important.

4. In an electric punch the induction coil retracts the spring-loaded striker. Everything else is very similar to the mechanical version of the instrument.

How to make a punch with your own hands

For those who do not want to pay 300 - 500 hard-earned rubles for a center punch of more or less normal quality, there are several options for making this tool on your own. We have already mentioned the first one - from a hexagon.

To make a simple punch from this material, it is enough to grind its striking part, sharpen its tip to a given angle and harden it and the striker. And you can do this even on a regular gas stove, heating the metal to a bright pink glow. Although it is much faster to do this using gas burner or petrol blowtorch, which we hope you already have in your workshop.

The heated metal must be lowered for 4-5 seconds. into the water, then for 1 second. remove and lower again another 10 -15. If you perform the same procedures, but dip the tool in oil, it will turn blue, which is even better.

You can also quickly make a primitive, but quite workable center punch from an old drill whose side edges have lost their functionality, and therefore cannot be sharpened, by simply sharpening its end.

However, we still do not recommend using such a tool in its pure form - it is very fragile and can break upon impact and cause injury. As a last resort, put a piece of hose on it high pressure, as in the version in the photo, but better - select a metal sleeve from a tube of suitable diameter or grind it.

In addition to the options mentioned, there is a way to make a center punch from almost any steel, but only carbon steel can be hardened. If you are not sure about the carbon content in it, then you can check this by sparking when processed on a grindstone. And here is the video:

And if you did not see the long-awaited stars when sharpening a suitable rod for making a center punch, then you can carry out the cementation process, which we mentioned at the beginning of the article. There are two ways to do this at home. If you have a welding machine on your farm, then the one shown in the video is the most acceptable and simple.

And if the acquisition welding machine is still in the plans, then look for a nearby metalworking plant where they sharpen cast iron parts and collect cast iron shavings, the smaller the better.

Or buy cast iron powder online. Having heated the metal to the same bright pink glow, lower the part of the workpiece that needs to be quenched into cast iron shavings. The carbon from the cast iron will move into the surface layer of your mild steel and allow it to harden.

The procedure can be repeated several times, but sharpen the center punch before it. However, the instrument can be repaired in the future in the same way.

Dear readers, if you have any questions, please ask them using the form below. We will be glad to communicate with you;)

When working with metal, a craftsman often has to drill holes. During this procedure, the drill bit often slips to the sides, thereby creating great inconvenience. This can be prevented by using a device such as an automatic center punch.

Standard

A regular punch is made in the form of a handle equipped with a rod, for the manufacture of which special tool steel is used. The purpose of the center punch is to make small indentations in the surface of the metal into which the tip of a drill bit for a hand or electric drill will later be inserted. The punch tip is equipped with a cone-shaped sharpening specifically for the drill. The handle of the device is equipped with special notches. They prevent your hand from slipping while working with the tool. According to consumer reviews, the disadvantage of a conventional punch is that you have to work with two hands (hold a hammer in one, and a punch in the other).

For those who want to free one hand and exert a minimum of effort while working, it is recommended to use an automatic center punch. It can be mechanical, spring and electrical.

Spring center punch

A mechanical or spring center punch can be operated with one hand. This tool operates by tightly compressing and self-releasing a special spring.

Inside the body of this tool there is a cocking and trigger mechanism, which affects the firing pin and the working part of the capper. The cone-shaped rod performs punching by hitting it with a striker. It starts moving after the spring is released.

Benefits of the tool

Judging by the reviews of the owners of such products, the spring automatic center punch has the following advantages:

• Marking is done with one hand: no percussion instrument is used.
• The master has the opportunity to control the force of impact with a cone-shaped rod on metal surface. This function, which is available in an automatic mechanical punch, allows you to safely process soft and fragile materials without the risk of damaging them: the same depth - characteristic feature for all holes made with this tool.
• The marking procedure with a mechanical center punch is much faster than with a standard one.

Electric automatic punch

The operating principle of this tool is to use a striker and a rod, which move not from human effort, but due to the action electrical circuit. Using a solenoid (inductor) and the created short-term magnetic field the striker, being drawn into the body of the instrument, releases the firing pin. That, in turn, affects the rod. As numerous consumer reviews testify, using such an automatic punch, you can make at least fifty holes within one minute. As users note, electric cores are rare. This is explained by the fact that these tools have an outdated design.

Where can I buy the device?

You can purchase a center punch of one type or another at locksmith shops. Tools are also sold in the hand and power departments. The cores are cylindrical in shape and are easy to spot on the shelves. Before purchasing this tool, it is recommended to pay attention to what material it is made of and who its manufacturer is. If there are no identification marks on the core body, experienced craftsmen We recommend that you refrain from purchasing this tool.

German manufacturer

Rennsteig produces contact pressing and percussion instruments. The peaks, drifts and punches manufactured by this company are united by high German quality.

Using the Rennsteig automatic punch, marks can be easily made along the marked line. To do this, place the tool in the desired location and press the cap. The punch works itself, without the use of impact devices.

Characteristics

The German product Rennsteig is an automatic center punch, the device of which consists of the following elements:

• Housing made of very high quality tool steel. It has a nickel plating.
• Replaceable hardened tip. Its length is 1.25 cm.
• Drummer. Its diameter is 0.14 cm.

The center punch is also equipped with a mechanism for adjusting impacts.

Using this tool, you can mark both ordinary steel and products made of any non-ferrous metal.

Do-it-yourself automatic center punch

Those who want to get a device for markings, but at the same time save money, or just those who like to tinker, can try to make a standard core. A regular diesel injector is suitable for this purpose, namely its shut-off needle, which is highly hard. It can freely core plastic, aluminum, copper, brass, bronze and high-carbon non-hardened tool steels. For those who want to work without using hammers, it is better to make an automatic core from a duralumin pipe. To work you will need:

• A duralumin pipe with a diameter of 0.12 cm. It will become the body of the future product.
• Shock-cocking mechanism. It is a cone-shaped product made of durable carbon steel, which is located at a slight offset inside the charging spring.
• Ordinary spring. It should be placed between the striker and the core plug.
• Cover or plug. It acts as a stop for the trigger spring, which acts on the firing pin.
• Striker. It is easy to sharpen it yourself using a sharpening machine or grinder.
• Sharpened cone-shaped rod. There may be several of them. In this case, if necessary, during work they can be removed and sharpened one by one.

Progress

It is not difficult to make an automatic core yourself if you work in stages. The wizard is required to perform the following actions:

• Make a punch rod. It is desirable that it have a diameter of 0.4 cm and a length of 4 cm. The working surface must be hardened.
• A shock-absorbing washer is installed on the striker shank. After this action, it is considered ready for use.
• Prepare the firing mechanism. To do this, install a machined part in the form of a cone in the inner part of the spring. This work should be performed in such a way that the thin part (0.3 cm) of the part rests against the end of the striker. Its length can be 3 cm.
• Insert the trigger mechanism into the body of the future tool.
• The upper part of the pipe closes silently at the end. For this purpose, the tube is equipped with a thread onto which the cap is screwed.

As a result, a homemade punch should act as follows:

• A sharpened cone-shaped rod is placed at the intended location for punching, after which it should be pressed.
• With its second blunt end it acts on the trigger mechanism: it pushes a cone-shaped part installed in the spring towards the firing pin.
• As a result of pressing the rod on the trigger mechanism, its cone-shaped part gradually moves more and more from the end until it hits the center of the firing pin. He, being under the influence of an ordinary spring, performs the blow.

The manufacture of a product can be considered successfully completed if, when the rod is pressed at the desired point, a mark is immediately formed on the surface. As numerous reviews from owners testify, it is convenient to store homemade cores and cores in chess boards. There, for each rod, you can make special sections made of polystyrene foam.

Homemade cores, both conventional and automatic, are the optimal solution for those who use this tool only occasionally.

Anyone who has ever tried to drill into solid surfaces knows how difficult it is to make a hole exactly in the intended location. The drill tries to slide at least a little to the side. I have to try again several times. But if there is already at least a small hole in the right place, the process goes much faster. But how to do it? For this purpose, a special core tool was invented, also known as a center punch.

A conventional core tool consists of one piece - a strong steel rod. This can be U8 steel, hardened to 65 HRG and tempered. Chrome-vanadium alloy or other durable types are used. One end is sharpened in the form of a cone, the other is flat. The rod itself can be seven-sided or round. The length of the center punch ranges from 10 to 16 cm, thickness - 0.8-1.2 cm.

The process of marking cores (holes for installing a drill) goes like this. Hold it with your left hand. The sharp end of the tool is placed at the location of the intended hole. With the right hand, a precise blow is applied with a hammer to the butt plate (flat part). A mark from the punch (core) appears on the surface being processed. This word should not be confused with the concept in geology, where it refers to rock obtained by drilling.

To prevent the hand from sliding over the tool during operation, the cylindrical surface is covered with special notches or knurling. The conical (working) part is sharpened at a certain angle. The sharper it is, the higher the marking accuracy. A core with a sharpening of 30-45° marks the centers of circles, 75° is used when marking a hole for a drill.

There is no point in sharpening the core with emery, since its material cannot be processed in such a way.

Application

Using a core, you can make marks on any surface. It is advisable to use it when working with smooth materials. These are tiles, polished surfaces. Most often it is used when drilling metal. Therefore, core samples are often referred to as metalworking tools.

Masons also actively use it. Special mason cores have been created for this purpose. They are not much different from locksmiths. They are often powder coated bright color to make it easier to find if lost.

A core is also used to make the processing lines visible. To do this, the applied markings are passed through with frequent cores, making it dotted.

What are they?

• manual;
• automatic;
• electrical;
• with special capabilities (a center finder for applying a core on cylindrical or spherical parts, a device for applying markings at the required distance from the edge of the workpiece).

Automatic center punch allows you to:

• mark with one hand;
• work without a hammer;
• adjust the force when working with delicate materials;
• obtain marks of the same depth;
• get the job done faster.

Automatic core allows you to make up to 50 shots per minute with a distance of 2 cm between holes.

Instead of a core tip, you can insert a stamp into the rod and brand the parts.

An automatic (mechanical) core looks a bit like a metal fountain pen. It consists of two chambers, each of which has its own firing pin. The first one is made in the form of a cut cone. There is a striker there, which will apply cores to the surface. Behind it is a spring-loaded impact striker with a guide rod. Its spring is slightly offset to the side.

Behind it inside the body is located through hole. In the second chamber there is a piston with a beveled edge, spring-loaded by a powerful spring.

When the tool is placed on the surface and with your thumb right hand press on the thrust cap, the striker rests against the edge of the spring-loaded piston, lifting it. The spring behind it compresses and creates counter pressure.

At the end of the compression process, centering and alignment occurs towards the primary chamber. This leads to the rod breaking off and falling sharply into the hole.

The spring pressure is transmitted to the firing pin through intermediate elements. It hits the surface of the material, and a hole from the automatic center punch remains on it.

In some models, the lower striker can be changed, thus extending the service life of the tool.

The impact force of the automatic core can be changed by turning the stop cap at the top of the tool. In this case, the spring underneath is weakened or compressed. The minimum impact force is 10 kg, the maximum is 15 kg. The depth of the hole is from 0.2 to 0.3 mm.

Electrical core

In electric punches, inside the body there is an electromagnet coil, a tip, a spring and a striker. After pressing the body, it lowers; the washer of the tip, which does not move at this time, closes the electromagnet circuit. The impact occurs when the solenoid retracts the ferromagnetic striker. He hits the tip, leaving a mark on the surface.

Which core to choose?

A simple core is the cheapest, an electric one is much more expensive. When choosing a tool for yourself, decide how often you are going to use it. If only from time to time, then a regular or inexpensive automatic one is enough (so that you can do without a hammer). For professional activity buy high-quality mechanical or electrical.