How to make a spotter with your own hands: the advantages of homemade equipment, making an apparatus from an inverter

Spotter is a machine designed for spot welding. This equipment is widely used for straightening and car body restoration. Due to the simplicity of the design of such devices, it will not be difficult to make a spotter with your own hands.

It is only necessary to use a high-quality inverter, on the basis of which the welding equipment is made.

Application features

If initially spotters were used only when performing various bodywork with cars, then today, thanks to the versatility of this equipment, it is possible to use it in everyday life for quality spot welding. With the help of self-made welding machines, all kinds of metal structures are performed, fences from reinforcement, the surfaces of body panels are straightened without the need for disassembly plating.

The main purpose of the spotter is precisely repair and restoration of car body panels

. In the case when it is impossible to align the parts from the inside, and their dismantling presents certain difficulties, spotters are used that allow high-quality welding, which in the future will be perfectly protected from the appearance of corrosion.

Principle of operation

Today, there are several options for the electrical circuits of spotters, which are made from an inverter, a transformer and an old battery. Self-made devices operate on the principle of a hammer, allowing you to pull out body elements without local painting, and the quality spot welding when using a working gun allows you to ensure the most reliable and durable fixation of bodywork elements.

A homemade spotter has several operating modes:

• Welding mode, using a carbon electrode, when all work is done at minimum power.
• A short-term mode, in which the guide is fixed with the help of special rings and the metal is pulled out during its point heating.

The most popular today are models of spot welding machines, which are made on the basis of an inverter. Such devices have a special additional gun, with the help of which a point heating of the metal elements to be connected is carried out.

Inverter-based device

Homemade spot welding machines made on the basis of a welding inverter are simple structures that have the power necessary to work with most metals and can be easily manufactured do it yourself.

The simplest spotters can consist of the following elements:

• Inverter housing.
• Cable.
• Sharp rod or electrode.
• Stadder pistol.

The easiest way to make such an apparatus for resistance welding is using inverters, to which a welding gun is attached through a cable. You can use both ready-made purchased stadder pistols, or make them yourself on the basis of a metal sealant pistol.

Advantages of self-made spotters:

• The ability to pull out metal parts without damaging the original paint layer.
• Ease of use.
• Versatility of application.
• Possibility to perform metal upsetting using graphite electrodes.
• The presence of two or more modes of welding.
• Simplicity of design.
• Affordable cost of the components used.

You can find various schemes for the manufacture of inverter spotters. You can choose both the simplest models that are intended for their domestic use, and professional installations that combine power, versatility and advanced capabilities.

For self-assembly of the device, you will need the following components:

• Contact group for 220 volts.
• Diode bridge.
• Control relay for 30A.
• A transformer that lowers the voltage by 12 volts.
• Thyristor 200 Volt.
• Control buttons.

Connection to the network is carried out using a diode bridge and a transformer. The thyristor circuit and the contact diode group in the inverter increase the voltage, after which the current is fed through the cable to the working welding gun.

The transistor diode unit used must withstand the highest output current values, which reach 1500 Amperes. The power of the output welding current can be controlled using a bus, which is installed instead of the secondary winding.

Despite the seeming complexity, even the initial skills of reading electrical circuits and working with radio components will be enough for independent production of spotters, which can be used not only in everyday life, but also for performing various kinds body work.

It is only necessary to select a high-quality diagram of the execution of the device for resistance welding, and then fully adhere to the documentation available at hand.

Case and cables

The box of a self-made spotter can be made from scrap metal materials. Easiest to use for this job case from an old computer. The presence of a working fan will be an additional plus, which will reduce the temperature, allowing you to improve the operating time of the device without shutting it down for mandatory cooling.

Inside the case, it is necessary to install several fans that operate from 12 Volts and allow high-quality cooling of the power section of the inverter. The easiest way is to use computer fans that are directly connected to the control unit and work continuously or on a signal from temperature sensors.

The presence of compact fans inside the case allows to extend the continuous operation of the device at maximum power ratings.

It is best to use welding cables ready-made, purchased with a cross-section of at least 1 millimeter per 10 Ampere of power of maximum current indicators. For the mass, cables with a length of no more than 150 centimeters are used, and the working wire is no longer than 250 centimeters. Otherwise, there may be a loss of current strength, which negatively affects the operation of the device and the quality of welding.

At both ends of the cable, threaded connections are attached to fix the welding gun and connect it to the inverter. Due attention should be paid to the quality of the connection, since the losses of the welding current depend on this. On the back of the power cable for the mass, a quick-clamping clamp is installed or terminals with threaded fasteners are used.

Execution of a working gun

The main working element of the spotter is a welding gun, which allows for spot heating of the metal. If you plan to constantly use the equipment, then it is preferable to purchase a ready-made factory pistol, which is distinguished by its simplicity of design, reliability and durability. If the spotter is made for occasional use, then it is quite possible to assemble a working pistol from improvised devices.

The easiest way to do it is from an assembly glue gun, to which a reliable and comfortable handle made of textolite or other non-conductive materials is attached. In the glue gun, appropriate holes are made for the guides, to which the used electrode is subsequently fixed. The cable from the inverter is connected to the gun and when the trigger is pulled, a short powerful pulse is applied.

The holding bracket, which fixes the welding electrode, is made of a copper tube of rectangular or square cross-section. Copper rods with a diameter of 8-10 millimeters are used as electrodes.

You can find various schemes and options for manufacturing a resistance welding gun, which involve changing the electrode without disassembling the completed device.

Reverse hammer assembly

One of the advantages of using a spotter is the quick change of working tools, which expands the functionality of such equipment. To perform straightening and welding bodywork, a reverse hammer is used, or as it is also called in another way, inopuller. Making the simplest reverse hammer with your own hands is not difficult. It is carried out on the basis of a metal assembly gun.

A part is cut off from the old assembly gun that holds the cylinder with sealant and polyurethane foam. Three rods with a diameter of no more than 10 millimeters are welded onto the vacant site. To the free ends of the rods, a ring is fixed by welding, which is made from a rod with a cross section of 6-10 millimeters. The diameter of the ring should not exceed 100 millimeters.

At the pistol rod, the stops and the curved part are cut off. Instead, a fastener is welded to which the cable from the welding inverter is subsequently connected. The cable can be secured with two nuts and an M10 threaded bolt.

With the help of the hammer, high quality spot welding and straightening work can be carried out without damaging the original paintwork.

If desired, you can purchase ready-made reverse hammers, which differ in the diameter of the working body and are designed for use on spotters with different powers.

Spotter from the welding machine

The easiest way is to make a spotter from a welding machine with your own hands. In this case, you only need to equip the unit with a thyristor and a diode with the required parameters, which will allow for pulse welding. Additionally, the welding machine can be equipped with a solenoid relay, which allows you to adjust the power of the impulse.

The spotter from the welding machine is carried out in full accordance with the existing scheme, and all that remains to be done is purchase or make your own working gun and reverse hammer. Separate spotter execution schemes imply the ability to switch operating modes when the inverter used can work as a classic welding machine, as well as a device for spot welding.

Making a spotter with your own hands will not be particularly difficult. Such a device for resistance spot welding can be made from an inverter or an old welding machine. It is only necessary to have on hand a high-quality scheme according to which the assembly of the device will be carried out. It is possible to make used working guns and reverse hammers from tools for spraying polyurethane foam and sealant. Making such equipment with your own hands will significantly save on the purchase of equipment manufactured by industrial in a way, while the functionality of home-made equipment will not differ from expensive purchased aggregates.