How to make a knife for foam plastic from a soldering iron. Where to get an electric cutter for cutting foam. Advantages of buying a soldering iron or a do-it-yourself foam cutter from our company

Heat and sound insulation building materials on the market are presented in wide range, is polyethylene foam, 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, polystyrene foam does not change its physical and chemical properties. Polyfoam also has sufficient mechanical strength.

Polystyrene foam also has very important properties, such as fire resistance (when exposed to fire, foam plastic does not smolder like wood), environmental friendliness (since polystyrene foam is made of styrene, even food products can be stored in containers made from it). Fungi and pockets of bacteria do not appear on the foam. Practically perfect material for insulation and sound insulation during the construction and renovation of houses, apartments, garages, and even packaging for food storage.

In stores building materials polystyrene foam is sold in the form of plates of 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.

The video clip clearly demonstrates how easy it is to cut polystyrene foam on a homemade machine.

When wanting to make a cutter for polystyrene foam 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 are attached nichrome wire for 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 extend beyond the bottom side of the base, and when fully unscrewed, it would provide 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 (efficiency factor), kilowatts of electricity will be wasted.

Sometimes you need to process the foam, give it the required form, trim, cut... You can use a knife for this, but it is inconvenient, the cuts are not always even, it is difficult to cut the material, and even the sound is terribly annoying to most people. You can heat the knife, but this is inconvenient as it will constantly cool down. We will make a small and simple cutter for foam plastic and more.

The basis for the foam temperature cutter will be a small wooden block. You can choose any dielectric handle for yourself or carve it, for example, into lathe beautiful and comfortable. The one in the photo also suits me, it is convenient to work with, it has the shape of a rectangular parallelepiped, its length is 13 cm, and its width and height are 1.4 cm.

Our thermal cutter will not exactly cut the foam, but melt it. It is very convenient to give any shape to a piece of foam plastic with such a cutter and you can get the hang of it and make real masterpieces. The heating element is a small piece of metal wire that has a high resistivity; its thickness (diameter) is about 0.6 mm. Examples of such metals and special alloys: tungsten, nichrome, constantine, fechral, chromal. You can buy wire made from such metals, and if you can’t find it on sale, then remove it from an old hair dryer, toaster, or some other simple appliance in which something is heated. A small piece of wire will act as a resistor, which is supplied with a current greater than it should, as a result of which such power is dissipated on it that it heats up.

You will not be able to solder a wire to a high-resistance wire with a regular soldering iron, no matter how hard you try, you can, of course, first transfer some copper to the ends by electrolysis, but we will secure it to a bar with a pair of nails or screws.

You can use many things as a current source, for example, a low-power transformer, a switching power supply. The alternating voltage from the transformer winding does not even need to be rectified by a diode bridge. If there is laboratory block power supply, adjust the volts or limit the amps to a value that will provide the desired temperature for melting foam or other similar materials. I often use a 12 Volt power supply - 0.5 Ampere (it gets noticeably hot during long-term use). The wire running from the burner to the energy source must be elastic and withstand constant bending, for example, it can be a specialized one speaker cable. The load will be connected through a small 5.5 x 2.1 mm power socket.

If you want to make a thick tip or, for example, in the shape of a knife, then it will have very little resistance. To warm up such “stings” you need to apply small value voltage, volts, two, three. Transformers with such a miniature output voltage are rare, so if you are rewinding an ordinary one, then remove the standard secondary winding and take several pre-connected in parallel copper wires to get a total diameter of about 5 mm, the maximum current depends on it. It is also worth remembering that if the current transformer is designed for low power, then you will not get a large current and voltage out of it. It will be very cheap to buy a power supply unit for fluorescent lamps (electronic transformer) and remake it; there are a lot of instructions on the Internet on how to turn such a thing into a normal UPS.

It turns out that operating temperature The cutter cools down instantly and even after disconnecting from the power supply. Therefore, in order not to waste energy in vain and not once again overload what gives us voltage, we attach a miniature tact button to the gap. Look at the permissible current in this button so that it can withstand such a powerful load.

You can give your cutter any shape you like. I ended up with something like a heating saw knife. In this case, a thick wire almost does not heat up due to its low resistance, but a cutting wire, on the contrary, heats up well. If I connect a low-power power supply, the filament just heats up, and if I take a powerful transformer, the nichrome filament just gets red-hot, it looks cool (it shines very brightly in the dark, just like an incandescent lamp!), but this high temperature I just don't need it.

Standard construction has long since sunk into oblivion. This is noticeable when visiting areas low-rise construction. 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 that select 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, and 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 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.

For ease of use, strings for cutting foam plastic (you can use old strings, for example from a guitar, having a spiral winding) are installed at its ends wooden handles. 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).

Curly carving on foam plastic using this tool is 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. In order to better cut a thick sheet, it is necessary to 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 homemade cutter for foam plastic.

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 hex bushings with internal threads. 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 to charge the car’s batteries). 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

The delights of architectural design also require insulation. In order to preserve their expressiveness, it becomes necessary to manufacture complex elements. How to cut out such 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 on large angular velocities at average linear feed. To install the manufactured fragments on the façade, ceresite is used.

Laser cutting polystyrene foam is the most advanced technology, combining hot cutting tool and the accuracy of the automated system. Laser cutting of foam plastic makes it possible to produce parts of any complexity with highest precision with minimal 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 By finished products and be economically feasible.

Polystyrene foam (extruded polystyrene foam) is used as thermal insulation for external and interior decoration, used for packaging goods or manufacturing prefabricated structures. The material is produced in the form of sheets, which are cut on site and adjusted to the dimensions of the surfaces. To quickly cut foam plastic you will need special device, allowing you to make a straight or curved cut.

Manual processing of polystyrene foam is possible at home and in small workshops using simple device, assembled from scrap materials. Extruded polystyrene foam has a fairly dense structure, so You can cut slabs with a metal tool, heated to a certain temperature. A wire that supplies electric current is suitable as a cutting surface, the supply of which is associated with the main difficulty of assembly.

A self-made machine makes it possible to obtain tiles or bars of suitable thickness from ordinary polystyrene foam for packaging for their further use in various structures. This device can also be used to cut foam rubber or similar materials that are needed for manufacturing or repair. upholstered furniture. The compact dimensions of the device for cutting foam plastic with your own hands using nichrome allow you to install the machine in a small workshop or even on a balcony.

To cut polystyrene foam at home, you will need a structure that can be assembled from simple materials, available at any hardware store. You must first determine the parameters of each element, taking into account the size of the foam boards that will have to be processed . In most cases, the following details are sufficient:

The base is made of dense plywood, chipboard or solid wood. You can order new parts or use elements old furniture(doors, walls, shelves). To work with foam plastic, a base of 400 x 600 mm is sufficient.
String or wire in the form of a thermal knife for foam plastic.
Metal posts, screws, springs or regular nails to secure the wire. The installation height of the cutter depends on the expected thickness of the finished slabs.
Fastenings for parts on the base. A few self-tapping screws are enough to secure the structural elements.

To assemble the thermal cutter, you will need up to one hour of working time. Each of the structural elements can be quickly replaced during repairs or expanding the capabilities of the device.

Algorithm of actions

To make a device for cutting foam plastic or similar materials, you need the most common tools (hammer, screwdriver, pliers). You can work anywhere with sufficient space (balcony, room, hallway, garage, etc.). No assistance or outside specialists will be required.

Assembly is carried out in the following order:

Legs can be attached to the base, which will increase stability when cutting foam with a string.

How to choose cutting wire

A suitable cutter can be made from nichrome wire (X20N80), which is used in the design of most household appliances as heating element. By mechanical characteristics nichrome is comparable to ordinary steel, but differs in greater resistivity and heating limit up to temperatures of +1200 ºC. Wire with a diameter of up to 10 mm is available for the manufacture of cutting devices.

Precise and smooth carving of foam plastic is possible by heating the cutting line to a temperature that is two to three times higher than the melting threshold (+270 ºC). It should be borne in mind that such a process involves energy consumption for the absorption of heat by the material itself in proportion to its density. Therefore, for effective and safe cutting you need to select a wire of suitable thickness to prevent the metal from melting at maximum heating.

Calculation and preparation of the electrical part

For safe operation of the device, it is necessary to correctly install the current-carrying elements, which are connected to the power source through plug-in terminals. To cut the material, you can use alternating or direct current. The power of the source is calculated based on the fact that to effectively cut 10 mm wire you will need up to 2.5 W (for 500 mm - 125 V).

The current voltage is proportional to the resistance and is calculated using formulas or tables. But on average, with a wire diameter of 0.8 mm, a length of 500 mm and a resistance of 2.2 Ohms, you will need a current source of 12 V with a load current of 12 A. Changing the length up or down will require a similar increase or decrease in voltage at the same force current

Electricity sources and connection diagram

Safe cutting is ensured by connecting to a regular 220 V household network via a car transformer. To adjust the voltage, a handle is provided in the single primary winding, with which the graphite wheel is moved and the voltage is removed from the corresponding area. This parameter can be changed within the range from 0 to 240 V. Connection to the current source is made through the terminal box.

When connected homemade machine To cut foam plastic to the electrical network, you need to make sure that the phase does not fall on the common wire. All necessary parameters and connection diagram can be found on the transformer body. Before connecting to the network, you need to check the functionality of the device using a multimeter.

A simpler option for supplying current to the wire is to use conventional step-down transformers with taps from the secondary windings. In that case no need to adjust the voltage, since this value is always constant and sufficient to heat the wire to the desired temperature. You can select the desired value during the initial setup of the transformer by providing a certain number of winding turns in the circuit.

You can also heat the wire for cutting foam using household appliances. The following nuances are taken into account:

It must be taken into account that the cutting tool under voltage will immediately be hot, so you should not touch it to check the temperature.

To make a thermal knife for polystyrene foam or foam rubber, it does not require a significant investment of time and effort. A wire of almost any diameter is suitable for this, but with unknown parameters (diameter, resistance), you need to increase the power gradually, first connecting low-power current sources. Great value has reliable contact insulation and phase position control, which cannot be connected to the wire.

The issue of home insulation is very relevant these days. Cladding house facades with foam plastic is one of the most popular types of insulation. And this is very justified, because... the process of such insulation is simple and clear, and all necessary materials always available for free sale.

But everyone knows that gluing foam plastic is very convenient on flat wall. With any method of gluing foam plastic to the wall: using dry mix glue, foam or foam glue, it is always very important that the foam sheet fits tightly to the wall and does not create air gaps.

If the wall is smooth, then no questions arise. But, unfortunately, the walls of old houses are not ideally even. Yes and different design features structures sometimes create differences in the plane of the wall.

This drawback can be partially mitigated by laying the foam on a thicker layer of glue. But the maximum permissible thickness of the adhesive layer often cannot cover the magnitude of the differences in the plane of the walls. In addition, too large differences lead to unjustified overuse of glue.

The only way out of the situation remains is to trim the foam according to its thickness. But doing this with a hacksaw is very inconvenient and time-consuming, especially if you need to cut a large amount of foam. In addition, during cutting, a large amount of debris is generated in the form of foam balls. And the surface is uneven and the accuracy of such cutting is very conditional.

In order to quickly and evenly cut foam to the desired thickness, you can use a foam cutting machine. This device can be made independently, absolutely with your own hands.

Operating principle and design of the foam cutting machine

The operating principle of the machine is based on the fact that foam plastic easily melts under the influence of temperature. Thus, if you run a thin heated wire over it, it is easily cut, forming a perfectly flat, smooth surface.

To manufacture the machine, the following components are needed:

LATR (laboratory autotransformer) or car battery;
nichrome thread;
racks for fastening nichrome thread;
spring (1-2 pcs.);
board-tabletop;
copper wire.

A nichrome thread (spiral) is used as a cutting object. You can either buy it in a store or extract it from old household appliances in which they were used as filaments (hair dryer, for example). The thickness of the spiral can be 0.5-1 mm. The most optimal thickness is 0.7 mm. The length depends on the width of the foam that will be cut.

An important element of the device for cutting foam is LATR. But if it doesn’t exist, then it can be made using an old transformer and a device for charging car batteries.

You can also use a computer power supply, in which wires providing 12 W (yellow and black) are used to connect to the spiral.

To operate such a machine, it is enough to have an output voltage of 6-12 W.

It is necessary to correctly adjust the length and thickness of the filament so that it matches the voltage. If the thread gets too hot, it may burst. Well, if the thread heats up slightly, then cutting will occur slowly.

Can also be used as a power source car battery. It can be used in conditions where there is no electricity on the site.

For different tasks you can do different designs devices for cutting foam.

Basically, these devices will differ in the length of the spiral. To cut polystyrene foam into bars, you need a short spiral length.

You can install two spirals and cut the sheet into several bars in one pass.

Two spirals cut the sheet into three parts in one pass. The stand has guides for smooth feeding of foam.

But, as a last resort, foam plastic can be cut into bars with a hacksaw. It is much more difficult to cut foam plastic to thickness, and even to a given size. Therefore, let’s look at how to make a machine for cutting foam plastic to width.

Step-by-step instructions for making your own machine and cutting foam plastic

Step 1. Preparing the tabletop. You can take any piece of chipboard as a tabletop for a machine for cutting foam plastic with your own hands. the right size. The surface on which the foam will move must be smooth. Holes for the racks are drilled in the tabletop. It is convenient to use metal pins with threads with a diameter of 10-12 mm as racks. The height of the racks should correspond to the thickness of the foam sheets plus a headroom. The pin is fixed with nuts.

To give the structure stability, bars are attached to the bottom of the tabletop, which will also serve for the safe passage of the electrical wire.

Step 2. Connecting the current supply wires. From below, under the tabletop, the wires are connected to metal stand rods: the wire is wound around the lower end of the pin and pressed with a bolt.

The second end of the wires must be connected to a power source, depending on the selected method. The most best connection there will be a connection through a plug that will connect to the LATER socket. Connection is possible through self-clamping terminals, as well as by twisting and soldering. This depends on the selected power source.

In any case, the connection must be made in accordance with the rules for working with electrical installations and devices, be convenient for work and safe during operation.

Step 3. Fastening the nichrome spiral. A nichrome spiral is fixed between two posts. A spring is attached to one end of the spiral (there may be two of them).

The spring is needed to tension the nichrome thread during operation. The fact is that when heated, the nichrome thread lengthens and sags. A thread in this condition will not produce a quality cut. Therefore, the thread is fixed in an initially tense state, so that the spring is slightly stretched.

To attach the nichrome thread to the pin, washers with an internal diameter slightly larger than the diameter of the pin are used. A small hole is made in the washer for attaching the spiral itself. A small sharpening is also done on the inner diameter side so that the washer can be fixed on the thread of the pin.

A spring with a spiral attached to it is inserted into one washer and placed on the first pin. The second washer is put on the second pin and drilled hole thread a nichrome spiral. Next, it is tightened so that the spring stretches and fixed.

Step 4: Cutting the foam. To unravel a sheet of foam into two sheets given size, the spiral is set to the desired height. The required distance is measured with a ruler.

The machine is then connected to a power source. The thread heats up and now you can cut the foam, smoothly moving it forward along the countertop.

The cutting speed depends on the filament temperature, which in turn depends on the applied voltage and the thickness of the filament itself. You should not try to apply more voltage to achieve high speed, because... this can lead to rapid filament burnout. Here, a balance between tension, thickness and length of the thread must be selected experimentally. The thread should not overheat during operation. When heated, it turns red or scarlet. But it should not turn white - this indicates that the thread is overheating and that it is advisable to reduce the voltage, otherwise the thread will not last long in this mode. Of course, smooth adjustment is easy to do if LATER is available. But if it is not there, then a laboratory power supply can be made from computer unit nutrition, the video below has more information. After you have made this foam cutting machine with your own hands, you need to make sure that the device is safe.

It must be remembered that all activities must comply with safety regulations for working with electrical appliances. The power source must be grounded and all connections must be carefully insulated. All work on assembling the machine must be carried out with de-energized wires. The machine is connected to the electrical network only while working with polystyrene foam. After work it must be turned off immediately. When operating the machine, avoid touching metal parts and the nichrome thread itself.

Step 4: Cutting the foam at an angle. Sometimes it becomes necessary to cut the foam so that one side is higher and the other is lower.