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 metal tool , heated to a certain temperature. A wire feeding wire is suitable as a cutting surface. electricity, the supply of which is associated with the main difficulty of assembly.
A self-made machine allows you to make tiles or bars from ordinary polystyrene foam for packaging. suitable thickness with their further use in certain designs. 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 ordinary tools(hammer, screwdriver, pliers). You can work anywhere with sufficient space (balcony, room, hallway, garage, etc.). No helpers or third party specialists not 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 efficient 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 work The device must be correctly mounted with current-carrying elements that are connected to the power source through plug-in terminals. To cut the material, you can use variable or D.C.. 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 polystyrene foam to the electrical network, you need to make sure that the phase does not fall on 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 this case no need to adjust the voltage, since this value is always constant and is sufficient to heat the wire to desired temperature. Pick up desired value It is possible during the initial setup of the transformer by providing a certain number of turns of windings 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 importance has reliable contact insulation and phase position control, which cannot be connected to the wire.
Polystyrene foam (expanded polystyrene) is an extremely beneficial material for the home craftsman or builder. Its most valuable qualities are low thermal conductivity, light weight, manufacturability, and durability. This allows it to be used both as insulation and as a structural material for the manufacture various forms, models, blanks, packaging, basics for small architectural forms. Expanded polystyrene is made in the form of large blocks measuring more than a meter on each side, and then cut into plates required thickness, from 3 to 20 cm thick (on request).
To fulfill your creative or construction plans, you have to cut foam plastic to required sizes and shapes yourself. Polystyrene foam can be cut quite easily with a knife or hacksaw. But in this case, the structure of the foam plastic is destroyed, since it consists of sintered “balls” of polystyrene foam. Extruded foam plastic is a single mass, but it can also crumble. Therefore, for cutting foam plastic, it is most convenient to use special electric thermal cutters. Their working body is usually a thin nichrome wire, which heats up to several hundred degrees when an electric current is passed through it. Upon contact with it, the foam instantly melts and forms a durable sintered layer. The cut area is neat, even and does not crumble.
To work with small flat sheets, it is most convenient to use a tabletop cutter with a vertical wire arrangement. The basis of such a cutter is a frame made of a metal profile or wooden blocks (if it is small). At the bottom of the frame there is a working surface - a table. It can be made from thick plywood, chipboard, sheet metal or textolite. In general, any durable flat material. Hanging from above the frame (see sketch) is a nichrome wire, which is passed through a hole in the table. If the table is made of flammable material, then a piece of metal tube should be pressed into the hole for the wire, flush with the surface of the table.
At the top the wire is attached to the frame with a screw, at the bottom a weight of several hundred grams is suspended from the wire. The fact is that when heated, the wire greatly elongates and a weight serves to maintain its tension. The ends of the wire are brought electric wires. If the table is made of metal, then it should be insulated from it top beam frame to which the wire is attached. For example, the very end of the beam may be wooden. If the table is made of dielectric material, then the frame can be completely metal.
This cutter is convenient for cutting. sheet material, carry out figured cutting, since the sheet can be rotated in any direction. For high-quality cutting, it is better to mark the line of the future cut on the foam.
However, for “cutting” sheets big size and thickness, as well as in conditions where it is impossible to bring foam plastic to the work table (for example, when performing work on insulating a house, cutting off excess and protruding parts, making holes in a whole sheet of foam plastic), manual electric cutter. You can also make it yourself.
To make it you will need any hacksaw, preferably with a split handle. Using a cutting machine - grinder, we cut the teeth from the blade. (They won’t go to waste - they can be used to make a good garden hacksaw with a narrow blade).
At the end of the remaining sheet we drill a hole for attaching nichrome wire. We attach a tin plate to the handle to secure the other end of the wire. Of course, it should not touch the hacksaw blade.
To compensate for the stretching of nichrome when heated, we install a small but strong spring. When the wire is cold, it should be well stretched, and when heated, it should maintain a slight tension so that the wire maintains straightness. We connect the wires to the ends of the wire (a hacksaw blade is used as a conductor on the end of the wire farthest from the handle). Now the manual foam cutter is ready.
It cuts expanded polystyrene better than a hot knife cuts butter. However, it must be taken into account that figured cut It is impossible for them to do it, only straight (due to the flat blade of the hacksaw). You cannot change the “route” of the cut during the process - you only need to cut straight. If you need to cut out a piece with a complex shape, you will have to do it in several iterations.
The power that is dissipated by the wire should be approximately 100-150 W per 50 cm of its length. The wire resistance is usually 1-3 ohms. The operating temperature is on the verge of reddening the wire. A step-down transformer can be used as power supply. Its secondary winding should have 6-12 volts with a current of up to 10 A. However, it makes sense to “bother” with a transformer if the cutter will be used very often and a lot. If the work with the cutter is quite occasional, then it is wiser to use a small battery. In addition, this greatly frees up your hands in terms of mobility. After all, with a battery you can work even while standing on a stepladder and move around the entire construction site. And from the point of view of electrical safety, the battery is better.
When working with small parts or for very precise adjustment of dimensions, as well as for shaped cutting, you can use a cutter made on the basis of a pulse soldering iron. A pulse soldering iron is a transformer with a very high current and low voltage on the secondary winding. The tip of such a soldering iron is a small V-shaped piece of thick nichrome. It is connected to the secondary winding of the transformer and heats up in a matter of seconds before high temperature. Therefore, as a cutter you can use a soldering iron with both a standard tip and a homemade one. Homemade cutter Made from thick nichrome wire. They give her the required form and clamped to the soldering iron terminals instead of a regular tip.
A wood burning device can also serve as a good cutter for foam plastic, especially if this model has a tip made of nichrome wire. A cutter for polystyrene foam can also be made from a regular soldering iron, the tip of which is a copper rod. There is no need to remove the rod, but you can make an attachment for it - a knife and tin. The soldering iron should be more powerful, 60-100 W, so that the nozzle warms up well.
As you can see, there are a lot of ways to cut foam, so choosing the most suitable one for a specific requirement is not difficult.
Konstantin Timoshenko © 11.11.2011
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Polystyrene foam is a good heat insulator, characterized by durability and low weight. It is used to create a variety of shapes, blanks and models, as an excellent insulation material. It's quite easy to work with. But often such material is produced in the form of blocks with large geometric parameters. Cutting them with a saw or knife is very inconvenient. Products crumble, which disrupts their structure.
Problem with opening thermal insulation material solves the foam cutter, often called a cutter. You can purchase it at a hardware store or make it yourself. In the second case House master gets at his disposal a tool that suits him in all respects.
Elementary carver – half an hour and you’re ready!
The simplest tool for cutting sheets of foam plastic (foamed polystyrene) can be made without the slightest difficulty using 4-5 flashlight batteries and an ordinary guitar string. The process for creating a carver will be as follows:
- the batteries are connected in series to form one unit;
- A guitar string is attached to the ends of the resulting module.
As a result of these actions, a tool with an electric closed arc is obtained. The current passing through it will heat up the string. In the area of its contact with the material being cut, the process of melting and cutting of the polystyrene foam sheet into two parts will be observed.
For the described homemade thermal knife to work, the string must be heated to 130–150 °C. With this simple tool you can cut 1-3 blocks of foam. Use it for cutting large quantity sheets is impractical due to the fact that the batteries will run out very quickly.
Types of electric thermal knives and their features
If a master uses polystyrene foam regularly and performs large volumes of work, it is advisable for him to make a tool with his own hands that operates from household appliances. electrical network.Such homemade thermal knives that do not require separate chargers, used for:
- linear cutting;
- figured cutting.
They use a nichrome thread or a metal plate as a working thermoelement. A mandatory unit of such devices is a transformer that reduces the voltage (Figure 1). Its windings must meet the following requirements:
- cable cross-section – from 1.5 mm;
- voltage - from 100 V (primary winding), 15 V (secondary).
Experts recommend connecting the step-down device to an autotransformer (LATR), which allows you to smoothly adjust the output voltage. If you don’t want to purchase such an expensive device, you can do otherwise:
- place a switch on the secondary winding taps;
- equip the step-down transformer with a rheostat.
Linear cutting device - how to make?
A homemade thermal knife for cutting flat sheets of expanded polystyrene foam is simple design. The principle of its creation will be understood by any craftsman.
The basis of the structure is a frame made of steel profile or wooden blocks. A working surface made of particle boards, plywood large thickness. Some craftsmen use PCB sheets for its construction.
The function of a working surface can also be performed regular table or a workbench. Then there is no need for a frame. And the process of constructing the structure itself is as follows:
- Two vertical supports are mounted on a table (another flat surface), which are secured with insulators.
- A transformer is connected to the latter through electrical contacts to reduce the voltage.
- Nichrome wire is stretched between the insulators. A special weight is suspended from it. It is needed to tension the thread.
This foam cutter operates simply. An electric current passes through the thread, heating it, which leads to stretching of the wire. The load does not allow the latter to sag.
The heated nichrome thread easily cuts the foam block horizontally, which is moved by hand. As a result, flat sheets of insulating material are obtained. Their thickness is determined by the distance separating the stretched wire from the working surface of the table.
When performing the described operation, it is important to ensure the supply of polystyrene foam at the most uniform speed possible.
In cases where the material needs to be cut vertically, the design of the cutter is slightly modified. The frame must be additionally equipped with a holder. Hang a nichrome thread and a weight from it, passing the latter through a hole pre-drilled in the table. It is advisable to install a hollow metal pipe in it, which will protect the master from burns when the wire is heated.
Rules for making tools for figure cutting
If cutting at home will involve sheets of foam plastic that are large in thickness or geometric dimensions and do not fit on work surface due to its parameters, it is recommended to make a thermal knife from a hacksaw or hand jigsaw.The work is performed as follows:
- The cutting blade of the jigsaw (hacksaw) is removed.
- An electrical cable is connected to the handle of the tool.
- Nichrome wire is bent at a given angle.
- The figuratively bent thread is installed in the place where the canvas was previously located and secured with nuts and screws.
All metal elements on a self-made structure are insulated. If desired, you can immediately bend it under different angles several nichrome cloths. Then figured cutting will be more comfortable.
Those who are planning to insulate an apartment or a newly built house with their own hands should definitely familiarize themselves with the methods by which foam plastic is cut at home, because this is one of the most popular and available ways isolation.
Foam is a foam material and is mostly air, so it is very light and easy to work with. However, you should not think that no problems arise, because besides everything, foam is a rather fragile material. Therefore, if you use electric grinder, then you shouldn’t hope for smooth edges, and besides, the entire room and area will be strewn with crumbled foam.
No matter how sharp the knife is, the material will still crumble. Of course, this is a minor defect and the sheets will be suitable for use, but cleaning will turn into a troublesome task. There is a way out of this situation; you can use a thermal knife. In this case, the edges of the material are melted and it does not crumble. But bad luck, such a device costs a lot, but in principle you can heat an ordinary knife. However, in this case you need to be very careful so as not to get burned, and the work will be significantly delayed.
For this purpose, you can use various cutting tools, for example, a grinder, only then you should use the thinnest disk. Very often builders use simple sharp knife. Sometimes it is advised to use a hacksaw with very fine teeth, but the latter method is very questionable. In addition, stores sell special thermal knives designed for working with foam plastic.
The thermal knife heats up to 600 °C in just 10 seconds. However, this tool is quite expensive, so it doesn’t always make sense to buy it.
The way out in many cases will be a device for cutting foam sheets, made independently. It is probably somewhat cumbersome, but if you have the necessary components, it is absolutely free and always available. And if you have to do large-scale work, for example, you have in front, which you built for your big family, then the question of how to conveniently cut foam plastic, and even a lot and quickly, will not come up throughout the entire event, no matter how long it drags on.
In order to assemble a cutter for foam plastic, you will need a tabletop, a pair of springs, M4 screws and 28 mm long stands, as well as a nichrome thread, which will act as a cutting tool. First, we make two holes in the base, press the posts into them, and cut a small groove at the base of the screw head, thanks to which the thread will be securely fixed in the given position.
When everything is assembled, we attach the string to the screws, but since it can sag during heating, it should be connected through springs, then the thread will always be in a tense position. The power source is connected to such a device using ordinary twists. This way you can make a homemade and very effective foam cutter, while spending a minimum of effort, time and money.
Trying to cut the foam yourself
Now let's talk a little about various technologies, methods and, of course, we present detailed instructions what to do and how to do it.
How to cut polystyrene yourself - step-by-step diagram
Step 1: Preparatory work
It doesn’t matter what kind of tool you are going to use - a knife, nichrome thread or other cutting devices, you still need to start with markings. So we take a ruler, a square, a tape measure, a pencil and make marks on the surface of the sheet, then we connect them into lines. In general, we draw the contours of the future section.
There are other ways you can. For example, using nichrome thread. In this case, a small current is supplied to it, which is capable of heating the string to the desired temperature, and cutting is carefully carried out along a given contour. Of course, the quality of the cut in this case will be much better, but you will have to work a little to make the machine. Therefore, this method is not always justified if you need to process only a few sheets; there is simply no point in spending time constructing a device. As you can see, it is impossible to give a definite answer as to what is better for cutting foam, it all depends on the volume and skills.
Polystyrene foam is universal material. It is used in construction (insulation), in the production (repair) of household electrical appliances, interior design, and advertising. One of the main characteristics of the material is density. The higher this indicator, the stronger material. However, this greatly affects the price.
When using material as a filler for wall insulation, the loosest structure is usually chosen (due to low cost). However, loose foam is difficult to process - when cut, it crumbles heavily, creating difficulties when removing debris.
The knife for cutting foam must be thin and sharp, but this does not prevent the edge from breaking. Even if you work outside, flying small balls clog environment.
That's why professional builders cutting foam plastic nichrome wire or hot plate. The material is fusible, despite fire safety.
Important! When choosing insulation, pay attention to the characteristics. It should say “self-extinguishing.” Such foam is perfectly cut using temperature, but in the event of a fire it will not become a source of combustion.
An industrial foam cutting machine can process sheets of any size and cut the material both across and along the massif.
However, cutting foam plastic at home does not involve such volumes and sizes. At repair work In your home (or garage), a compact thermal knife is quite enough. It can easily cope with both linear cutting and shaped fitting of slabs when laying in areas with complex shape.
Any tool has a cost, and there is always an opportunity to save on your purchase.
DIY tools for cutting foam plastic
The guillotine is perfect for linear cutting. Only the impact will not be mechanical, otherwise a lot of debris will be formed. We use proven technology - cutting foam plastic with a heated tension string.
Required materials
- Nichrome (tungsten) thread
- Power supply, preferably regulated
- Any construction materials: timber, metallic profile, pipe, for making a tension frame
- Furniture drawer guides.
On a table, workbench, or other flat surface, install vertical racks for attaching the guillotine. Using furniture guides, we secure the cutter frame so that it moves without distortion. Both sides must move in sync. 
The most important part of the cutter is the wire mechanism. The first question is: where to get the material. Nichrome can be purchased in stores selling radio components. But since we are striving for a shareware design, we will look for an alternative.
- Old soldering iron. Models made in the USSR, designed for 36-40 volts, can be found in any home workshop. The heater winding is an excellent donor for a nichrome guillotine. True, the length of the wire is no more than a meter.
- Iron with a classic spiral heater. The wire is thicker, suitable for linear cutting. Shaped cutting acceptable, with low accuracy requirements.
- Spiral heaters from a hair dryer or fan heater. The principle is the same, they are not suitable for precise cutting.
note
Tip: When straightening the spiral, do not pull the wire along the spring. Loops may appear and the thread will break. It is better to unwind the turns as if from a spool of thread. You can put a spiral on a nail or pencil and pull the wire across the turns.
The principle of operation of the frame is shown in the diagram
The wire cutter must be electrically isolated from the frame. Therefore it can be made of metal. It is important to ensure constant tension on the wire. When heated, nichrome expands, adding up to 3% in length. This causes the string to sag.