Do-it-yourself automatic punch: principle of operation and device

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

automatic punch rennsteig


An ordinary punch is a locksmith tool made in the form of a handle equipped with a rod, for the manufacture of which special tool steel is used. The task of the punch is to make small recesses in the metal surface, into which the tip of the drill for a manual or electric drill will be inserted in the future. Specially under the drill, the center punch is equipped with a cone-shaped sharpening. The handle of the device is equipped with special notches. They prevent slipping of the hand while working with the tool. According to consumer reviews, the disadvantage of a conventional binder is that they have to work with two hands (holding a hammer in one and a center punch in the other).

DIY center punch

Those who want to release one hand and use minimal effort during operation are advised to use an automatic punch. It can be mechanical, spring and electric.

Spring punch

Mechanical or spring punch can be operated with one hand. This tool operates due to tight compression and independent release of a special spring.

automatic punch device

Inside the body of this tool contains a cocking and trigger mechanism, which has an effect on the firing pin and the working part of the nakronivatel. A cone-shaped rod is screwed by using a striking blow on it. He comes into motion after opening the spring.

automatic center punch working principle

Tool Benefits

Judging by the reviews of the owners of such products, a spring automatic 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 a metal surface. This function, which has an automatic mechanical punch, allows you to easily process soft and brittle materials without risking damage: the same depth is a characteristic feature for all holes made with this tool.
  • The marking procedure with a mechanical punch compared to the standard one is much faster.

Electric Auto Center Punch

The principle of operation of this tool is to use the striker and the rod, which come into motion not from human efforts, but due to the action of the electric circuit. With the help of a solenoid (inductor) and the generated short-term magnetic field, the striker, being pulled into the tool body, releases the striker. That, in turn, has an effect on the core. As evidenced by numerous consumer reviews, using such an automatic punch, you can make at least fifty holes in one minute. As users note, electric cores are rare. This is explained by the fact that these tools are outdated.

Where can I get the device?

You can purchase a punch of one type or another in locksmith shops. The tool is also sold in the departments of manual and electrical equipment. Cores have a cylindrical 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 is its manufacturer. If there are no identification marks on the core body, experienced craftsmen recommend to refrain from buying this tool.

German manufacturer

Rennsteig manufactures crimping pliers for pressing contacts and percussion instruments. The chisels, chisels, spikes, drills and center punches made by this company are united by high German quality.

Using the Rennsteig automatic punch, you can easily mark along a marked line. To do this, the tool must be installed in the desired place and click on the cap. The center punch works itself, without the use of percussion devices.

automatic punch


The German Rennsteig product is an automatic punch whose device consists of the following elements:

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

Also, the punch is equipped with a mechanism for adjusting strokes.

Using this tool, it is possible to mark both ordinary steel and products from any non-ferrous metal.

DIY center punch

Those who want to get a device for marking, but at the same time save money, or just amateur tinkers can try to make a standard core. For this purpose, a conventional diesel nozzle is suitable, namely its locking needle, which has high hardness. It can be freely pinned with plastic, aluminum, copper, brass, bronze and high-carbon non-hardened tool steels. For those who want to work without the use of hammers, it is better to make an automatic core from a duralumin pipe. For work you will need:

  • Dural pipe with a diameter of 0.12 cm. It will become the body of the future product.
  • Shock-cocking mechanism. It is a product in the form of a cone made of durable carbon steel, which is located under a small offset inside the cocking spring.
  • Ordinary spring. It should be located between the striker and the core plug.
  • Cover or cap. It serves as an abutment for the trigger spring, which affects the firing pin.
  • Striker. It is easy to grind it yourself using a grinder or grinder.
  • Sharpened conical rod. There may be several. In this case, if necessary, during operation, they can be removed and sharpened alternately.

Working process

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

  • Make a core punch. It is desirable that it has 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 shank of the striker. After this action, it is considered ready for use.
  • Prepare trigger mechanism. To do this, install the turned part in the form of a cone in the inner part of the spring. This work should be carried out in such a way that with its thin part (0.3 cm) the part abuts against the end face of the striker. Its length can be 3 cm.
  • Insert the trigger mechanism into the body of the future instrument.
  • The upper part of the pipe from the end is deafly closed. For this purpose, the tube is equipped with a thread on which the cap is screwed.

As a result, a home-made punch should act as follows:

  • The sharpened cone-shaped rod is attached to the intended place for punching, after which it should be pressed.
  • With his second blunt end, he acts on the trigger mechanism: pushes the cone-shaped part installed in the spring to the striker.
  • As a result of pressing the rod on the trigger mechanism, it gradually shifts more and more from the end with its conical part until it hits the center of the striker. That, being under the influence of an ordinary spring, and performs a blow.

automatic mechanical punch

The manufacture of the product can be considered successfully completed if, when pressing the rod at the desired point on the surface, a mark immediately forms. As evidenced by the numerous reviews of the owners, home-made center punches and rods are conveniently stored in chess boards. There, for each rod, special sections made of foam can be made.

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


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