How is the welding process using spotterSpotter is an apparatus for spot welding, which is widely used for straightening automotive work. Very often, such work requires maximum geometric accuracy and knowledge of all body panels placed on the vehicle. And it is rare when a quality straightening can be performed without special devices, in particular, a spotter.

Today we will talk about how to assemble a spotter with your own hands and what is the scheme of his work. So, self-made spotter will save a lot of money if you make them from the welding machine.


  • 1 Features of the spotter
  • 2 How does the spotter work?
  • 3 Spotter do-it-yourself based inverters
    • 3.1 Inverter spotter circuit
    • 3.2 Materials
  • 4 Key features and specifications spotter
  • 5 How to weld parts using spotter?

Features of the spotter

In what areas is spotter used Such a device as a spotter is used for the following needs:

  • body welding;
  • straightening the body surface without disassembling the skin.

Especially spotter comfortable when straightening body partswhich are difficult to access due to certain structural features. When repairing body parts using a spotter from a welding machine, you need to weld it to deformed parts special fasteners, which by means of a reverse hammer pulls spoiled metal. Also the spotter is able to heat it, so fast rigidity and form quickly return to the metal.

How does the spotter work?

How to make a spotter with a welding machine There are several spotter electrical circuits that can be assembled not only from an inverter, but also from an old battery or transformer. Homemade spotter acts like a hammerIt works in a dotted way, but in the opposite direction. It looks like this:

  • reverse hammer guide fixed to the damaged area on the body;
  • only a hammer in the form of a washer can move along the guide, which applies force to the point of its fixation.

Regular spotter has two modes of operation;

  • short-term, when the guide must be fixed at the desired point with special rings;
  • welding - welding is carried out at minimum power using a carbon electrode.

Spotter do-it-yourself based inverters

Kinds of spottersThe spotter of the welding machine is most common among home-made devices, despite the fact that there are other schemes for their assembly. So, spotters with their own hands can be assembled and not from welding machines, but they will be less powerful.

Spotter is a branch of resistance welding, however, unlike it, the design of the spotter eliminates the presence of ticksThat is why this device can be considered an analogue of an electric arc welding machine, where the voltage is passed through the car body. One contact is attached to the body, and the second contact is the stem and nozzle.

Below, we suggest that you familiarize yourself with the simplest spotter scheme based on a welding machine, which you can optionally modify.

Inverter spotter circuit

Working principle spotterSpotter, assembled by hand from the welding machine, includes two key elements:

  • welding inverter;
  • thyristor relay.

For self-assembly of this unit you will need:

  • 200 volt thyristor;
  • transformer, lowering by 12 volts for push-button control of the relay;
  • 30 amp relay;
  • diode bridge;
  • contact group (220 volts);
  • control button.

By means of a diode bridge transformer connect to the network, and to the bridge, in this case the thyristor of the electronic relay must be connected. The transformer is designed to power the control branch of the thyristor circuit.

The scheme of spotter work is as follows:

  • when you press the button S3, the discharge of the capacitor C1 is turned on, and for some time the resistor R1 and the thyristor V9 are turned on;
  • then alternating voltage is applied to the primary transformer winding using diodes D232;
  • there is a procedure for welding parts and the electrode;
  • when capacitor C1 is discharged, the thyristor closes and the winding of the power transformer de-energizes;
  • In this situation, the welding process comes to an end, and the capacitor C1 continues to be charged from the transformer T1 for further work.

Remember that the diode bridge and thyristor can be replaced by a triac. Homemade spotters should be carefully thought out from a constructive point of view. It should work correctly regardless of size and investment.


Invertor spotter for body repairIron for the spotter should be allocated in the amount of 35 to 40 square centimeters. There is no overheating on the thyristor, they are only in the areas that are located after the cable. Also the stock of ferrous metal is very hot with a diameter of 16 mm. It is desirable that it be made of brass.

As for the cable for the spotter, you need to choose with a cross-sectional area of ​​about 70 square millimeters, and for the mass and the hammer its length is 1.7 and 2.1 m respectively. You will also need to provide pulse control thyristor PM-40.

First, the secondary transformer winding is wound using a 6.5 by 4 copper bus in the third winding. It can also be replaced by aluminum. Then on the secondary winding you need to add two more. The final version of the apparatus consists of an aluminum transformer winding of 250 square millimeters, which is equal to 5 windings of six turns each.

Pay close attention to the appearance of the reverse hammer, which is the electrode. More often the handle is made on the basis of a glue gunand the working cable has a thermal insulation layer and a switching wire. Also remember that when heated, the thermal insulation layer begins to contract.

Key features and specifications spotter

Self-made or factory spotter, having an industrial purpose, has a number of such important functions:

  • The principle of operation of the spotter circuit based on the inverterconnection of parts by welding repair washers using spotter;
  • Spot welding using a metal electrode that pulls the metal panel;
  • the ability to heat metal parts with a carbon electrode and then cool them. Thanks to this function of the welding machine, it is possible to carry out the precipitation of metals;
  • spotter design features make it very simple and convenient in terms of operation;
  • the presence of two welding modes in the spotter. The first mode of permanent switching on with the use of a carbon electrode, and the second - with short-term switching, which is regulated in time. It is used with a metal electrode and is often used to weld washers;
  • presence in spotter forced cooling system and thermostat to turn off the welding machine when overheating and automatically turn it on at the right temperature for welding.

Main technical characteristics of the device:

  • 220 volts - the required supply voltage for the spotter to work normally;
  • 56-60 Hz - the required frequency of the AC network;
  • 10 kW - the maximum allowable power;
  • 1300 A - the maximum possible operating current;
  • about 8-9 V - voltage for the secondary winding of the apparatus for welding;
  • 0-1.2 seconds - time limit setting;
  • two working welding modes - a timer with precision welding and a continuous mode during normal welding and tempering;
  • 15 percent - performance in spot welding of metal parts, taking into account the maximum output power;
  • 75 percent - performance at coal vara, taking into account the maximum output power;
  • from 100 kg and more - traction condition for the needle;
  • 100 kg and above - traction condition for the washer;
  • 380 to 290 to 840 mm - the length, width and height of the product;
  • 32 kg - weight of the structure.

How to weld parts using spotter?

DIY spotter - wiring diagram and manualThere is a recognized technology of working with the help of a spotter, which was determined by body repair masters. It is relevant in the repair of hard-to-reach deformed body parts on the car. Often this scheme of work is applied to the deformed car doors, wings and other parts of the vehicle. It is relevant wherever efforts are directed to the outside of the working surface and where the deformed section of the structure is located.

Spot welding is performed using the incoming current, and then the local surface is leveled by an abutment or an inertial hammer. Due to such manipulations, rather quickly the damaged part of the car will stretch to its original position.

Then the deformed and leveled surface is ground. This should be done so that the points are removed from the welding and the work surface is smooth. Do not forget about the mandatory grounding for the body, the negative terminal must also be disconnected from the battery.

Spotter welding technology is as follows:

  • clean the deformed area on the automotive part until the metal surface is visible;
  • attach the grounding contact to the prepared surface;
  • weld fasteners;
  • capture these elements with the help of special tools and tools that will be needed for smelting metals;
  • we pull out the deformed area of ​​the surface of the metal structure;
  • The welded element can be easily removed by hand with the help of rotational movements;
  • clean the surface of the part that was being repaired and prepare this area for the putty.

To work with the spotter, regardless of whether it is homemade or factory, you need to have the skills of welding. Also you must follow the rules of operation of this unit and follow the rules for welding. All this will allow to repair the deformed part of the car quickly and successfully.

Spotter will be indispensable when performing all sorts of repair work on the car body, requiring a point focus. And as you could see, this device can be assembled with your own hands.