home · Other · Do-it-yourself thermal knife for foam plastic. Homemade device for cutting foam plastic - buy or make it yourself? Metal plate cutter

Do-it-yourself thermal knife for foam plastic. Homemade device for cutting foam plastic - buy or make it yourself? Metal plate cutter

Standard construction has long since sunk into oblivion. This is noticeable when visiting low-rise construction zones. Each home is individual and unique. But every household requires insulation, if it was not provided for during the construction process. It is unlikely that foam manufacturers will produce slabs custom size for small order volumes. You'll have to cut it. But how to cut polystyrene foam when installing thermal insulation for a building with your own hands?

Foamed polystyrene foam can be easily processed by cutting. Before cutting polystyrene foam at home, you need to determine the required accuracy and cleanliness of the cut. After this, select the necessary device for cutting foam from the following:

  • saw (hacksaw);
  • string;
  • thermal cutter;

There is no clear answer to the question: “What is the best way to cut?” as long as there is no certainty regarding the volume and linear dimensions of the parts being processed.

Foam plastic should not be milled due to the extremely low mechanical stability of the material.

Just cutting

When carrying out work on insulating foundations, underground communications, floors under screed, facades under plaster, special precision and evenness of the cut are not very necessary. Moreover, if the building has a simple facade configuration. In this case, you can use hand tool for cutting foam plastic: knife, hacksaw, metal string.

Their use will lead to the loss of granules at the edge of the cut and the formation of a not entirely smooth edge. The presence of a loose fit of the slabs can be leveled by filling the voids with polyurethane foam.

Straight-line cutting with a finely serrated knife is justified with a material thickness of 50 mm; a hacksaw can be used to cut insulation up to 250 mm thick. You can use a serrated kitchen knife to cut foam. We buy a hacksaw with a fine tooth at a hardware store.

To make it easier to use the string for cutting foam plastic (you can use old strings, for example from a guitar, that have a spiral winding), we install wooden handles at its ends. They cut the insulation with a back and forth motion, as if using a two-handed saw. Large slabs can be cut by two people. In this case, the sheet to be cut must be secured.

Before cutting the foam, cutting edges must be treated with liquid lubricant. This will create a certain comfort when working (improves gliding, reduces noise).

Figured carving on foam plastic using of this instrument extremely difficult.

We use a thermal knife

Cutting polystyrene foam with your own hands using a thermal knife is justified for slab thicknesses up to 50 mm. To cut a piece of polystyrene, the hot knife is advanced at medium speed, which ensures a quality cut without tearing out fragments or melting the edges.

Purchasing a longer blade for this device is not entirely beneficial. When cutting by hand, it is impossible to cut strictly perpendicular to the surface. The end of the sheet will have a bevel, which is extremely inconvenient during installation. To cut better thick sheet, it is necessary to make a cut on both sides, deepening the hot knife to half the thickness or a little more.

We make and use a thermal cutter

To cut polystyrene foam with your own hands, devices with a thin hot element are most often used. General principle The actions of any thermal cutter for foam plastic are the same.

The heated element separates the material, followed by sealing of the opened volumes. Using thermal cutters for foam plastic, we get a perfectly smooth cut, which is very important for quality work on insulation.

Purchasing a factory-made foam cutting machine is not economically feasible.

Only if you don’t decide to do this professionally and permanently. In most cases, when cutting out shaped elements is not required, you can use a homemade foam cutter.

Making a foam cutter with your own hands is quite simple and quite inexpensive. After the work is completed, it will not lie like a dead weight and take up space. It can be assembled and disassembled as needed. If there is no need, its components can be used for other purposes.

Before you make a foam cutter, you need to prepare everything you need:

  • blank for work surface;
  • nichrome wire;
  • laboratory adjustable transformer (LATR);

Chrome-plated nichrome wire can be used without a step-down transformer, but this increases the risk of electric shock.

  • electrical wire, fastening for it,
  • springs for thread tension;
  • adjustment mechanism.

When manufacturing and using the device, follow the rules for the design and operation of electrical installations.

To make equipment for cutting foam plastic, start by marking and trimming the working surface. Determine its geometric dimensions in accordance with the dimensions of the cut slabs. It is better if the table surface is larger than the sheet area.

We install racks (supports) with the possibility of adjustment. To do this, you may need a small device in the form of hexagonal bushings with internal thread. They will make it easier to adjust the cutting height. The cutting wire is tensioned using springs. We lay and fasten the electrical wire on different sides of the thread. We connect the other end of the cable to the LATR (if there is no LATR, it can be replaced by using an autotransformer for charging batteries car). The device is ready for use.

Cutting polystyrene foam at home should be carried out in compliance with safety measures. When heated, toxic smoke is released. Therefore, we cut out parts from foam plastic either outside, or use respiratory protection in a workplace equipped with exhaust ventilation.

Using such a device for cutting foam plastic allows you to speed up the process of preparing insulation fragments as much as possible.

We use automated systems

Delights architectural design also require insulation. In order to preserve their expressiveness, it becomes necessary to manufacture complex elements. How to cut similar details? More affordable option- processing of insulation by milling. But milling of foam plastic is not carried out for the reason that the cutter, when rotating, tears out quite large pieces of material.

Dense polystyrene foam has higher mechanical strength and is easily milled. Anything can be made from it: a letter, a number, a graphic element of any complexity. Even a hedgehog. It is recommended to cut penoplex at high angular speeds with an average linear feed. To install the manufactured fragments on the façade, ceresite is used.

Laser cutting of foam plastic is the most advanced technology, combining hot cutting tool and accuracy automated system. Laser cutting of foam plastic allows us to produce parts of any complexity with the highest precision with a minimum level of waste. Laser cutting of foam plastic ensures absolutely smooth surface cutting using a hot beam of directional light moving with high speed. There are no restrictions on the thickness of the material and the complexity of the element.

The choice of cutting equipment used for foam boards and extruded polystyrene foam must be conscious. Reply technological requirements for finished products and be economically feasible.

Cutting foam plastic doesn’t seem to be a difficult task, but to do it accurately, you need to have skill and know some secrets. How and with what to cut polystyrene foam at home and how to make a machine yourself to simplify this work? I'll tell you now!

The scope of application of polystyrene foam is very wide. This material is used to make parts for aircraft modeling, it is used in the manufacture of toys and furniture, three-dimensional letters or sculptural elements for advertising are cut out of it, etc. We are interested in a very specific area - construction.

Types of cutting

In construction, foam plastic is used as insulation for roofs, walls, floors, ceilings, foundations and other structures. In the vast majority of cases, thermal insulation consists of sheets of foamed polystyrene, which are sold in stores and have standard sizes.

During installation of sheets, they constantly need to be trimmed, and here the following cutting options are possible:

  1. Longitudinal. This refers to the case when you need to cut a sheet of foam along its plane, for example, into two parts. For example, to make two sheets 25 mm thick from one sheet 50 mm thick: neither a knife nor a hacksaw will help here;
  2. Transverse. When it is necessary to cut a piece from a sheet the desired shape, that is, you will cut perpendicular to the plane of the sheet itself. In this case, you can use a knife, saw and other similar tools;

  1. Through. Often it is necessary to make holes in the thermal insulation layer to enter an electrical cable, pipe or other communications. If you have some skill, you can get by with a knife, but there are more effective tools, which I will tell you about;

  1. Curly. It is used when the edge of a sheet needs to be cut according to a clearly defined pattern with curved lines and a complex profile. An ordinary knife will not work here, and a special tool will be required.

Cutting tool

Foam cutting can be done a variety of instruments. Most popular:

  • Construction knife. During insulation work, a knife is most often used to trim sheets. It can be a construction, stationery or shoe knife. The main thing is that it is well sharpened. The knife is carefully drawn along the cut line; strong pressure is not necessary. If the sheet is not cut through, it is broken along the slot;

  • Hacksaw. To cut thick sheets, it is convenient to use a hacksaw for metal or wood with a fine tooth. Special saws for foam plastic are sold;

  • Nichrome wire. A piece of thin nichrome wire is heated by passing an electric current through it. A hot string, fixed in a certain way and stretched, cuts foam like butter;

  • Thermal knife. In essence, this is a soldering iron, the tip of which is made in the shape of a knife blade. The blade heats up and perfectly cuts any plastic, including foam;

  • Laser ray. You can cut polystyrene foam using a laser. This technology is used when making sculptural elements or in large industries to cut out a wide variety of shapes.

In construction, cutting of even, rectilinear shapes is most often required, which a knife can handle quite well. In this case, a thermal knife is an ideal option.

If you need longitudinal cutting to thickness, a nichrome string is best.

How to make a cutter from nichrome wire

How to cut foam thickness? This question often arises before a builder when it is necessary to unravel a sheet of insulation and make it thinner. A nichrome wire cutter is suitable for these purposes.

The idea of ​​the machine is quite simple: a string is pulled over a tabletop made of board or plywood, through which a current is passed. The string is set horizontally at the required height, heats up from the current and cuts the sheet, which the cutter moves along the tabletop.

Making such a machine with your own hands is quite simple:

Image Description

Making a table top. Choosing a board for the tabletop. It can be thick plywood or MDF, solid board, for example, a door from a cabinet or a tabletop from a table.
We fasten the studs. We attach threaded steel studs to the corners of our tabletop. To do this, we drill holes and insert anchors into them, which we secure with nuts.
Heels on the reverse side. On the back side of the tabletop we stuff heels from boards. They are needed so that the ends of the studs do not rest against the floor, and the structure stands level. In addition, it will be possible to run wires under the tabletop.
First wire. We connect the first wire to the stud. It is better to wrap it around the anchor under the washer, solder it and tighten it with a nut.
Second wire. Similarly, connect and tighten the second wire with a nut.
Holes in washers. We take two washers that fit loosely onto the studs. Drill holes as shown in the photo.
Sharpening washers. Opposite the holes, along the inner edge of the hole in the washer, we sharpen. This is necessary so that the washer fits exactly into the grooves of the thread and cannot move along the stud.

Spring. We put the washers on the studs and put the holes inward. We thread the end of the spring into one of them. Any steel spring that works in tension, for example, from a folding bed, will do.
Attaching the wire to the spring. We tie a nichrome wire to the free end of the spring and measure the distance to the opposite pin. Leave a margin of 30-40 cm and cut off the excess.
String tension. Insert a screwdriver into the end of the spring and stretch it. With the other hand we pass the wire through the hole in the washer and tie it tightly.
Selecting a power source. It is best to use a step-down transformer, which gives an output of 6-12 V at a current of 6-10 A. Charging is suitable for car batteries, power supply for a computer, transformer from an old TV.
We adjust the tensioned thread in height. To do this, you can use a square, ruler or tape measure.
We connect the machine to the network. We connect the supply wires coming from the studs to the transformer outputs. Apply voltage to our cutter and wait 10 seconds for the thread to warm up.

cutting. We take a sheet of polystyrene foam and run it along the tabletop. The wire will cut pieces of the thickness we need from the sheet, which we set earlier.

When cutting polystyrene foam with a hot wire, toxic smoke is released. It is necessary to use a respirator and work in a well-ventilated area.

Conclusion

I think now you understand how and with what foam is cut. Eat different ways and tools, choose the right one for specific case. To better understand the topic, watch the video in this article and ask questions in the comments if you have any.

Polystyrene foam is used in many construction work. It has good thermal insulation. However, this is a rather fragile and crumbling material. Therefore, when cutting it, special equipment is used. Otherwise, the edges will be uneven, and the material itself will lose its thermal insulation qualities at the joints.

Special equipment is on sale. However foam cutter you can do it yourself. This will significantly save the family budget. How to create different variants tool for cutting foam plastic, it will be interesting for every master to know.

Tool type

Creating manual foam cutter, you should study the existing varieties of this tool. There are mechanical and electric varieties. If the foam product is small in size and cutting accuracy is not so important, you can give preference to the first option of the tool.

However, in order to ensure a tight fit of the foam boards to each other, it is necessary to ensure high cutting accuracy. The edges should be smooth. In this case, it is possible to create an insulating layer High Quality. Its heat loss will be minimal. When uneven cutting occurs between joints, large gaps. Through them, heat from the room will escape to the outside.

Professional designers and builders use exclusively electrical equipment for cutting foam. It is quite possible to create such a tool at home.

Simple electric cutter

Considering how to make a foam cutter, you should study the design of the simplest equipment of this class, which runs on electricity. In this case, you will need to prepare a thin guitar string and several batteries (for example, from a flashlight).

The operating principle of this equipment is simple. The battery structure forms a single unit. A guitar string is connected to it. When electric current passes through the circuit, it will heat up. It is in this state that the string can easily cut a sheet of foam.

When using such a tool, the material will melt. The string heats up to 120 ºС and even more. In this case, it is quite possible to cut several large slabs made of polystyrene foam. If you need to do a large amount of work, this option will not work. The batteries will run out quickly. We will have to provide an option for connecting the system to a household network.

Types of electric cutters

Electric foam cutter can be used for various purposes. This will determine the type of design and overall performance characteristics of the equipment. There are three main types of homemade cutters.

The first category is used for linear cutting. The second group includes cutters that perform shaped cutting of material. Designers use them. This type is used less frequently for home repairs. There is also a tool with a metal working plate.

Such equipment must have a step-down transformer in its circuit. It must be rated for a minimum power of 100 watts. Secondary winding The transformer must have a cross-section of at least 1.5 mm. It must withstand a voltage of 15 V. In this case, you can achieve high performance results.

Features of work

Studying how to make your own handheld foam cutter, it is also necessary to consider the operating features of such equipment. As mentioned above, such an instrument has a string. It heats up and melts the surface of the foam.

This material reacts quite poorly to heat. Therefore, it is important to maintain the technology of the entire process. Cutting using a hot thread is done quickly. This allows you to achieve high quality cuts.

It's easy to check the string's heating level. To do this, a test is carried out on a test piece of polystyrene foam. If, when immersing the thread, long pieces of material remain on it, it has not yet warmed up enough. If there is no foam on the string at all, then the temperature is too high. In this case, you will have to cool the instrument a little. With proper heating, you can perform fast, accurate cutting.

Line cutting cutter

Linear DIY foam cutter will allow you to create blocks from the material of the required dimensions. This significantly speeds up the work of the master. If necessary, this tool can be used to cut circles, triangles or squares into the foam.

Two racks are installed vertically on the table surface. Two insulators are attached to them. There's tension between them nichrome thread. This alloy heats up quickly, providing sufficient temperature for cutting. A freely hanging load is passed through one of the racks. Contacts from the transformer are connected to the thread.

The current passing through will heat it up. It will be taut all the time thanks to the weight hanging from one side. This is necessary, since the string may sag when heated. If desired, the design can be modified by adding a spring instead of a load. However, the original version is easier to implement.

Line cutting process

Considering how to make a foam cutter with your own hands, you also need to understand how to work with them correctly. Cutting can be done vertically or horizontally. To do this, the thread is pulled in the appropriate position.

If the string is stretched horizontally, you can use it to make the same cuts. The foam is pulled evenly across the table. The thread will cut it evenly into the required pieces.

When cutting a structure vertically, a frame made of metal or plywood is added. A holder is installed on it. An insulator and a nichrome string are connected to it. On its other side a load is suspended. It will go through a hole drilled in the table. It must be large enough and covered with a special insulating material. Next, you can perform vertical cutting.

Shaped cutting

If you need to cut fairly large sheets of foam or create decorative elements, sculptures made from this material, a special type of equipment is used. You can also make it yourself. It's manual foam cutter. It is made on the basis hand jigsaw or hacksaws. In them, the cutting element is changed to nichrome string.

If you need to create curly elements, you can make several tools various shapes. A wire is connected to the handle of the jigsaw. It must be carefully isolated. Otherwise, it will be unsafe to work with this equipment. A nichrome string is attached to the wire contacts. This can be done using nuts and screws with washers.

Also, a pulse soldering iron or wood burner may be suitable for creating such equipment. This tool is considered convenient. Their working element is removed from such equipment and replaced with a piece. In this case, the threads can be given different shapes.

Cutter with metal plate

Exists foam cutter, in the design of which it is used To create this equipment, you can remake a soldering iron. Equipment with a power of 60 W is suitable. Removed from the device a heating element. Instead, a plate is installed here.

One side of the copper blank needs to be sharpened. This will allow you to create a more accurate cut. The sharpening angle should not be made too large. The cutting will be done using heat. To find the required level, you will have to experiment on a test piece of foam.

This method is also used by craftsmen of various skill levels and profiles. If necessary, the copper plate can be replaced with a steel billet. This option will require more effort when sharpening. But with the help of such a tool you can cut denser polymer materials.

Choosing which one foam cutter more suitable for the work of a master, you should take into account the recommendations professional builders. The greater the volume of work performed, the more complex the design will be. A simple battery-powered cutter is quite suitable for cutting several blocks. However, to perform a large amount of work, preference should be given to network types of equipment.

When cutting, the foam heats up. At this moment, substances unsafe for human health are released into the environment. Therefore, the work is performed in a well-ventilated room or outside.

In order not to make a mistake with the cutting configuration, you should mark all the lines with a pencil before starting the action. This will avoid mistakes when cutting. These simple recommendations will allow you to do the job quickly, correctly and safely.

Having considered what options for foam cutters you can make with your own hands, every master will be able to choose the best option for myself.

Foam - light, durable, good thermal insulation material, which is very easy to work with. But it has one unpleasant feature: it is usually made in the form of slabs quite large sizes, which in the process of work have to be cut into smaller pieces. No matter how sharp the knife and saw are, they will not be able to accurately cut the slab, since mechanical action destroys the structure of the foam, causing it to crumble rather than cut. Therefore, you need to use a special foam cutter for cutting.

Foam plastic, like any material, requires cutting, which is why you need a cutter.

The simplest homemade foam cutter

This type of cutter is not difficult to make with your own hands. To do this, just take the thinnest guitar string and 4-5 large batteries for an electric flashlight. Having connected all the batteries in series into a single element, you need to connect a guitar string to its ends and secure it with electrical tape, closing the electric arc. Due to the electric current passing through the string, the string will heat up.

Image 1. Diagram of a cutter that allows you to cut flat sheets from a block of foam plastic.

At the point of contact with heated to desired temperature with a string, the foam sheet will instantly melt, dividing into two halves, the cut of which will be fused and even. But for normal cutting, the string must be heated to a temperature of at least 120-150º. When working, it will not be difficult to determine whether the string has warmed up enough, since when cutting foam plastic, small stuck pieces will remain on the string. The longer such pieces remain, the lower the temperature of the string. But if they don’t remain on the string at all, then this means that this kind of thermal knife is heated more than necessary.

Such a primitive foam cutter can easily cut 2-3 large layers of material. But with large volumes of work, the batteries run out quickly, so in such cases a cutter powered by electricity is used.

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Options for homemade electric foam cutters

Conventionally, such devices can be divided into groups:

  • cutter for linear cutting of foam plastic;
  • cutter for figure cutting polystyrene foam;
  • cutter with working metal plate.

But despite this division, all cutters have one thing in common.

To make them, you cannot do without a step-down transformer.

Such a transformer must be designed for a power of at least 100 W. Its secondary winding must be designed for a voltage of 15 V and have a winding wire cross-section of at least 1.5 mm.

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Foam Linear Cutting Cutter

Image 2. Diagram of a vertical cutter: 1 – cutting nichrome wire, 2 – load, 3 – frame, 4 – working surface.

Such devices are mounted from a working surface (you can use a table surface) with two vertical risers attached to it, two insulators attached to the risers, connected to two contacts connected to a step-down transformer and a nichrome thread stretched between the insulators, as well as a freely hanging thread passed through one of the risers cargo (image 1).

This foam cutter works very simply. Passing through a nichrome thread, electricity heats it up, and the suspended weight keeps the thread taut, preventing it from sagging, since when heated it stretches quite strongly. Sometimes, instead of a suspended weight, a spring attached to one of the risers is used to tension the thread.

The heated thread easily cuts the body of the moving foam, turning it into flat sheets, the thickness of which depends only on the distance from the table surface to the tensioned wire. All you have to do is endure uniform speed feeding foam over the table surface.

For vertical cutting of layers, a different cutter design is used, in which cutting wire stretched vertically (image 2). A frame, preferably welded from metal profile, but one made from wooden blocks (3) is also quite suitable.

The design of the frame provides for the presence of a holder-foot, to which a nichrome wire (1) is suspended using an insulator with a suspended load at the other end (2), passed through a hole drilled in the working surface. Since the nichrome thread will heat up, it is better to make the hole larger and insulate the wooden parts by inserting a metal hollow tube of hollow diameter into it, through the cavity of which the end of the wire with the load is brought out.

This foam cutter will not only easily cut big pieces polystyrene foam on blocks required sizes, but will also allow, if necessary, to cut squares, triangles, semicircles and other shaped holes in the material. To do this, just first draw a cutting line along the surface of the foam with a marker.

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Cutter for shaped cutting of foam plastic

If you need to cut sheets big size or thicknesses that, due to their size, cannot be placed on the workbench, then in such cases a manual electric cutter is used, converted from a hand jigsaw or a hacksaw, in which the cutting blade is replaced with nichrome wire.

Image 3. Diagram of a manual thermal cutter: 1 – nichrome cutting wire, 2 – screw with nut and washer, 3 – textolite handle 4-5 mm thick, 4 – electrical cord.

Such an electric cutter is not difficult to make with your own hands. At the same time, for the convenience of figure cutting, several working tools can be made different shapes(image 3). The cutting blade of a jigsaw or hacksaw is removed, and an electric wire (4) is connected to the handle (3). Although the voltage will not be too high, the handle is still the same as others metal elements, it is better to insulate at least with ordinary electrical tape. Instead of the cutting blade to the supplied electrical cable using screws and nuts with washers, a nichrome wire bent as required is attached (4).

As an option, you can also use a wood burning device or a pulse soldering iron to design such a cutter. Such a cutter will be even more convenient, since the electrical wire is initially provided for in the design of these devices. To turn these devices into an electric cutter for foam plastic, it is enough to replace the heating working tools in them with a piece of thick nichrome wire, giving it the desired shape.

Such hand-held cutters are convenient because with their help you can not only cut sheets of foam plastic, but also cut out all sorts of recesses and cavities in them, remove chamfers, in a word, not just cut foam plastic into pieces, but sculpt real works of art from it.

Heat and sound insulating building materials on the market are presented in a wide range, these are foamed polyethylene, mineral and basalt wool and many others. But the most common for insulation and sound insulation is extruded polystyrene foam and polystyrene foam, due to its high physical and chemical properties, ease of installation, low weight and low cost. Polystyrene foam has a low thermal conductivity coefficient, a high sound absorption coefficient, and is resistant to water, weak acids, and alkalis. Foam is temperature resistant environment, from the minimum possible to 90˚С. Even after decades, foam plastic does not change its physical and chemical properties. Polyfoam also has sufficient mechanical strength.

Foam plastic still has very important properties, this is fire resistance (when exposed to fire, foam does not smolder like wood), ecological cleanliness(since polystyrene foam is made of styrene, you can even store it in containers food products). Fungi and pockets of bacteria do not appear on the foam. An almost ideal material for insulation and sound insulation during the construction and renovation of houses, apartments, garages, and even packaging for food storage.

In shops building materials foam is sold in sheet form different thicknesses and sizes. When repairing, foam sheets of different thicknesses are often needed. If you have an electric foam cutter, you can always cut sheets of the desired thickness from a thick plate. The machine also allows shaped foam packaging from household appliances into slabs like the photo above and successfully cut thick sheets of foam for furniture repair.

How easy it is to cut foam into homemade machine, the video clip clearly demonstrates.

When wanting to make a cutter for foam plastic and foam rubber, many are stopped by the difficulty of organizing the supply of supply voltage to heat the nichrome string to the desired temperature. This obstacle can be overcome if you understand the physics of the issue.

Machine design

The basis of the device for cutting foam plastic was chipboard sheet(chipboard). The size of the slab should be taken based on the width of the foam plates that are planned to be cut. I used a furniture door measuring 40x60 cm. With this size of the base, it will be possible to cut foam plates up to 50 cm wide. The base can be made from a sheet of plywood, a wide board, and the cutting wire can be secured directly to the desktop or workbench.

Pulling a nichrome string between two nails is the limit of laziness home handyman so I implemented the simplest design, providing reliable fixation and smooth adjustment of the height of the string during cutting above the surface of the machine base.

The ends of the nichrome wire are attached to springs mounted on M4 screws. The screws themselves are screwed into metal posts pressed into the base of the machine. With a base thickness of 18 mm, I selected a metal stand 28 mm long, so that when fully screwed in, the screw would not go beyond bottom side base, and when twisted to the maximum, it provided a foam cutting thickness of 50 mm. If you need to cut sheets of foam or foam rubber of greater thickness, then it will be enough to replace the screws with longer ones.


To press the stand into the base, first a hole is drilled in it, with a diameter 0.5 mm smaller than the outer diameter of the stand. In order for the posts to be easily hammered into the base, the sharp edges from the ends were removed using an emery column.

Before screwing the screw into the rack, a groove was machined at its head so that the nichrome wire could not move arbitrarily during adjustment, but would occupy the required position.


To make a groove in a screw, you must first protect its threads from deformation by putting on a plastic tube or wrapping it thick paper. Then hold it in the drill chuck, turn on the drill and attach a narrow file. In a minute the groove will be ready.

To prevent nichrome wire from sagging due to elongation when heated, it is secured to the screws through springs.

A spring from a computer monitor, used to tension the grounding conductors on the kinescope, turned out to be suitable. The spring was longer than required, so we had to make two of it, for each side of the wire fastening.

After preparing all the fasteners, you can fasten the nichrome wire. Since the current consumed during operation is significant, about 10 A, for reliable contact of the current-carrying wire with the nichrome wire, I used the fastening method by twisting and crimping. Thickness copper wire at a current of 10 A, it is necessary to take a cross-section of at least 1.45 mm 2. You can select the wire cross-section for connecting nichrome wire from the table. I had at my disposal a wire with a cross-section of about 1 mm 2. Therefore, each of the wires had to be made of two with a cross-section of 1 mm 2, connected in parallel.


If the electrical parameters of the nichrome wire are not known, then you should first try connecting a low-power electrical device, for example light bulb 200 W (a current of about 1 A will flow), then a heater of 1 kW (4.5 A), and so increase the power of the connected devices until the nichrome wire of the cutter heats up to the desired temperature. Electrical appliances can also be connected in parallel.

The disadvantages of the latest connection scheme for a nichrome spiral include the need to determine the phase for correct connection and low efficiency (coefficient useful action), kilowatts of electricity will be wasted.