The issue of home insulation is very relevant today. Sheathing the facades of houses with foam plastic is one of the most popular types of insulation. And this is very reasonable, because. the process of such insulation is simple and understandable, and all necessary materials always available for sale.
But everyone knows that gluing polystyrene is very convenient on flat wall. With any method of gluing foam to the wall: dry mix adhesive, foam or adhesive foam, it is always very important that the foam sheet fits snugly against the wall and does not create air gaps.
If the wall is even, then no questions arise. But, unfortunately, the walls of old houses do not differ in ideal evenness. Yes, and different design features structures sometimes create drops on the plane of the wall.
Partially, this drawback can be leveled by laying the foam on a thicker layer of glue. But the maximum allowable 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 overspending of glue.
The next way out of the situation remains - cutting the foam in thickness. But doing this with a hacksaw is very inconvenient and long, especially if you need to cut a large number of foam. In addition, during cutting, a large amount of debris in the form of foam balls is formed. Yes, and the surface is uneven and the accuracy of such cutting is very conditional.
In order to quickly and evenly cut the foam of the desired thickness, you can use a foam cutting machine. This device can be made independently, absolutely with your own hands.
The principle of operation and the device of the machine for cutting foam
The principle of operation of the machine is based on the fact that the foam is easily melted under the influence of temperature. Thus, if you draw a thin heated wire over it, it is easily cut, while forming a perfectly flat, smooth surface.
For the manufacture of the machine, the following components are needed:
- LATR (laboratory autotransformer) or car battery;
- nichrome thread;
- racks for attaching nichrome thread;
- spring (1-2 pcs.);
- tabletop board;
- 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 (a 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 to be cut.
An important element of the device for cutting foam is LATR. But if it is not there, then it can be done using an old transformer and a device for charging car batteries.
You can also use a computer power supply that uses wires that give 12 watts (yellow and black) to connect to the spiral.
To operate such a machine, it is enough to have an output voltage of 6-12 watts.
It is necessary to correctly adjust the length and thickness of the filament and to match the voltage. If the thread is too hot, it may break. Well, if the thread is slightly heated, then cutting will be slow.
A car battery can also be used as a power source. They can be used in conditions where there is no electricity on the site.
For different tasks, you can make different designs of the foam cutting device.
Basically, these devices will differ in the length of the spiral. To cut foam into bars, a short spiral length is needed.
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 is stuffed with guides for smooth feeding of the foam.
But, in extreme cases, foam plastic can be cut into bars with a hacksaw. It is much more difficult to cut the foam in thickness, and even with a given size. Therefore, we will consider how to make a machine for cutting foam in width.
Step-by-step instructions for self-manufacturing the machine and cutting foam
Step 1. Preparation of the countertop. As a tabletop for a do-it-yourself foam cutting machine, you can take any piece of chipboard right size. The surface on which the foam will move must be smooth. Holes for racks are drilled in the tabletop. It is convenient to use metal pins with a thread 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 margin in height. The pin is fixed with nuts.
To give the structure stability, bars are attached to the tabletop from below, which will also serve for the safe passage of an electric wire.
Step 2. Connecting the current supply wires. From below, under the tabletop, the wires are connected to metal rods-racks: the wire is wound around the lower end of the pin and pressed with a bolt.
The other end of the wires must be connected to a power source, depending on the method chosen. The best connection will be through a plug, which will be connected to the LATER socket. It is possible to connect via self-clamping terminals, as well as by twisting and soldering. It depends on the selected power supply.
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. Fixing the Nichrome Spiral. Nichrome spiral is fixed between two racks. A spring is attached to one end of the spiral (there may be two of them).
The spring is needed in order to pull the nichrome thread during operation. The fact is that when heated, the nichrome thread lengthens and sags. The thread in this state will not give a quality cut. Therefore, the thread is fixed in an initially stressed state, so that the spring is slightly stretched.
To fasten the nichrome thread to the pin, washers with an inner 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 from the side inner diameter 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 put on the first pin. The second washer is put on the second pin and in drilled hole thread a nichrome helix. Next, it is pulled so that the spring is stretched, and fixed.
Step 4: Cutting the Styrofoam To dissolve a sheet of foam into two sheets of a 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 temperature of the filament, which in turn depends on the voltage applied and the thickness of the filament itself. Do not try to apply more voltage to achieve high speed, because. this can cause the filament to burn out quickly. Here, a balance between tension, thickness and length of the thread must be selected empirically. The thread should not overheat during operation. When heated, it becomes red or scarlet. But it should not turn white - this indicates that the thread is overheating and that it is desirable to reduce the voltage, otherwise the thread will not last long in this mode. Of course, smooth adjustment is easily done if LATER is available. But if it is not there, then a laboratory power supply can also be made from a computer power supply, 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 machine is safe.
It must be remembered that all activities must comply with safety regulations for working with electrical appliances. The power supply must be grounded, all connections must be carefully insulated. All work on the assembly of the machine must be carried out with de-energized wires. The machine is connected to the mains only while working with foam. After work, it must be immediately turned off. When operating the machine, avoid touching metal parts and the nichrome thread itself.
Step 4: Cut the Styrofoam at an Angle Sometimes it becomes necessary to cut the foam in such a way that one side is higher and the other lower.
To do this, the spiral is set at a slope with the right parameters. In this way, foam sheets of various sections can be obtained.
Useful video
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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 soundproofing is extruded polystyrene foam and foam plastic, due to its high physical and chemical properties, ease of installation, low weight and low cost. Polyfoam has a low coefficient of thermal conductivity, a high coefficient of sound absorption, and is resistant to water, weak acids, and alkalis. Styrofoam resistant to temperature environment, from the lowest possible to 90˚С. Even after decades, the foam does not change its physical and chemical properties. The foam also has sufficient mechanical strength.
Styrofoam still has very important properties, this is fire resistance (when exposed to fire, the foam plastic does not smolder like wood), environmental friendliness (since the foam plastic is made of styrene, even food products). Fungi and foci of bacteria do not appear on the foam. An almost ideal material for insulation and soundproofing in the construction and renovation of houses, apartments, garages, and even packaging for food storage.
In the shops building materials Styrofoam is sold in the form of plates of different thicknesses and sizes. When repairing, foam sheets of different thicknesses are often needed. With 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 turn into plates, as in the photo above, and successfully cut thick sheets of foam rubber for furniture repair.
How easy it is to cut foam homemade machine, clearly demonstrates the video clip.
If you want 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 was a chipboard sheet ( chipboard). The size of the plate must be taken based on the width of the foam plates that are planned to be cut. I used a 40x60 cm furniture door. 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 string can be fixed directly on the desktop or workbench.
Stretching a nichrome string between two nails is the limit of laziness home master so i implemented the simplest design, which provides reliable fixation and smooth adjustment of the height of the string during the cutting process above the surface of the machine base.
The ends of the nichrome wire are attached to the springs, dressed on M4 screws. The screws themselves are screwed into metal racks pressed into the base of the machine. With a base thickness of 18 mm, I picked up a metal stand with a length of 28 mm, so that when fully screwed in, the screw does not extend beyond the bottom side of the base, and when the maximum unscrewed state provides 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 rack into the base, first a hole is drilled in it, with a diameter of 0.5 mm less than external diameter racks. In order for the racks to be easily hammered into the base, the sharp edges from the ends were removed on 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 occupied the required position.
To make a groove in a screw, first its thread must be protected from deformation by putting on a plastic tube or wrapping thick paper. Then clamp the drill in the chuck, turn on the drill and attach a narrow file. In a minute, the groove will be ready.
To prevent sagging of the nichrome wire due to elongation when heated, it is fixed to the screws through springs.
A suitable spring from a computer monitor, used to tension the ground wires on the kinescope, turned out to be suitable. The spring was longer than required, I had to make two of it, for each side of the wire attachment.
After preparing all the fasteners, you can fix the nichrome wire. Since the current consumed during operation is significant, about 10 A, for reliable contact of the current-carrying wire with nichrome wire, I used the method of fastening by twisting with compression. 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 section for connecting nichrome wire from the table. I had a wire with a cross section of about 1 mm 2 at my disposal. 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 must first try to connect a low-power electrical appliance, for example, a 200 W electric light bulb (a current of about 1 A will flow), then a 1 kW (4.5 A) heater, and so increase the power of the connected devices until the nichrome the torch wire does not reach the correct temperature. Electrical appliances can also be connected in parallel.
The disadvantages of the last 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 spent uselessly.
Styrofoam is a versatile material. It is used in construction (insulation), in the production (repair) of household electrical appliances, interior design, advertising. One of the main characteristics of the material is density. The higher this value, the stronger the material. However, this greatly affects the price.
When using the 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 cutting, it crumbles a lot, making it difficult to clean up debris.
A foam cutting knife should be thin and sharp, but this does not prevent the edge from breaking. Even if you work outdoors, flying small balls litter the environment.
Therefore, professional builders cut the foam with nichrome wire or a hot plate. The material is fusible, despite the fire safety.
Important! When choosing a heater, pay attention to the characteristics. It should say "self-extinguishing". Such foam is perfectly cut with the help of temperature, but in case of fire it will not become a source of combustion..
An industrial foam cutting machine can process sheets of any size, cut material both across and along the array.
However, cutting foam 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 curly adjustment of plates, when laying in areas with complex shapes. 
Any tool has a cost, and there is always an opportunity to save money on a purchase.
Do-it-yourself foam cutting tools
For linear cutting, the guillotine is excellent. Only the impact will not be mechanical, otherwise a lot of garbage will be formed. We use a proven technology - cutting foam plastic with a tension heated string.
Required Materials
- Nichrome (tungsten) thread
- Power supply, preferably adjustable
- Any structural materials: beam, metal profile, pipe, for the manufacture of a tension frame
- Furniture guides for drawers.
Sometimes you need to process the foam, give it the desired shape, cut it, cut it ... You can use a knife for this, but it's inconvenient, the cuts are not always even, it's 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 cutter will be a small wooden block. You can choose for yourself any dielectric handle or carve, for example, on lathe beautiful and comfortable. The one in the photo is also suitable for me, it is convenient for her to work, she has the shape of a rectangular parallelepiped, her length is 13 cm, and her width with a height of 1.4 cm.
Our thermal cutter will not exactly cut the foam, but will melt it. It is very convenient to give any shape to a piece of foam with such a cutter and you can get used to it and make real masterpieces. The heating element is a small piece of metal wire with a large resistivity, thickness (diameter) I have it somewhere 0.6 mm. Examples of such metals and special alloys: tungsten, nichrome, constantine, fechral, chromal. You can buy a wire made of such metals, and if you cannot find it on sale, then remove it from an old hair dryer, toaster, or some other simple technique in which something is heated. A small piece of wire will act as a resistor, carrying more current than it is supposed to, causing it to dissipate so much power that it heats up.
You won’t be able to solder the wire to a high-resistance ordinary soldering iron, no matter how hard you try, you can, of course, first transfer a little copper to the ends by electrolysis, but we will fix it on a bar with a pair of nails or screws.
A lot of things can be used as a current source, for example, a low-power transformer, a switching power supply. The alternating voltage from the transformer winding can not even be rectified by a diode bridge. If there is a laboratory power supply, adjust the volts or limit the amps to values at which there will be desired temperature for melting foam or other similar materials. I often use a 12 Volt PSU - 0.5 Amp (with long operation it heats up noticeably). The wire from the burner to the power source must be flexible and withstand constant bending, for example, it can be a specialized speaker cable. The load will be connected through a small power socket 5.5 x 2.1 mm.
If you want to make a thick sting or, for example, in the shape of a knife, then it will have very little resistance. To warm up such "stings" they need to be served small value voltage, volt, two, three. Transformers with such a miniature output voltage value are rare, so if you are rewinding an ordinary one, then we remove the standard secondary winding, and take several connected in parallel in advance 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 do not pull out a large current and voltage from it. It will be very cheap to buy a PSU 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 to operating temperature the cutter instantly cools down even after being disconnected from the power supply. Therefore, in order not to waste energy in vain and not to overload once again, what gives us voltage, we attach a miniature clock button to the gap. See the allowable current in this button so that it can withstand such a powerful load.
You can give your cutter any shape you like. I got something like a heated saw blade. At the same time, a thick wire almost does not heat up due to its low resistance, while a cutting one, 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 fried to red, it looks cool (it shines very brightly in the dark, just like an incandescent lamp!), But I just don’t need such a high temperature .
Styrofoam is quite practical and lightweight thermal insulation material. It is often used to create various crafts. However, in the process of working with it, one has to face one trouble - the material is difficult to cut. Foam plastic is produced in the form of large slabs, and in order to divide the panel into fragments, you will need to cut it.
Using a saw or knife for this purpose will not work. This is due to the fact that with any mechanical action, the structure of the material is destroyed. To avoid this, you will need to design a foam cutter with your own hands.
The simplest device for cutting foam
The simplest foam cutter is easy to do with your own hands. For this purpose, you will need to use the thinnest guitar string. In addition, you should prepare 5 large batteries for a conventional electric flashlight. They must be connected in series. A string is connected to the ends of the device, thereby closing the electric arc. The current will pass through the string, heating it.
When using such a device, the foam sheet will separate into two parts immediately after touching the string. In this case, the material will melt along the cut edges. The cut with such processing is obtained as even as possible. The string for cutting foam must be heated to a temperature of at least 120 degrees. However, it should not exceed 150 degrees.
Checking how hot the string is is quite simple. During cutting, stuck pieces remain on the edges of the material. If they are too long, the string is not heated enough. In the absence of such pieces, it can be judged that the string is overheated.
When using such an elementary device, about 3 foam panels can be processed. However, it is not suitable for large volumes of work. Batteries run out pretty quickly. To extend the time of the cutter, you will need to build a mains-operated device. A few simple tips will help you understand how to make a foam cutter.
Homemade electric foam cutters
If we divide such devices into groups, they should be classified as follows:
- device for linear cutting;
- thermal cutter, with which curly cutting is performed;
- device with a metal plate.
However, despite this classification, each device has one common element in its design. To create foam cutters, you will need to find a step-down transformer. It is necessary that this element withstand 100 watts.
Linear cutter
To create such devices, it is necessary to prepare working space. Usually a table is chosen for such purposes. Two vertical risers are attached to it. Each of them must have an insulator. A nichrome thread must be pulled between the insulators. A freely hanging load is hung on it. The nichrome thread is connected to the contacts connected to the step-down transformer.
The principle of operation is quite simple. The nichrome thread heats up when connected, which makes it easy to cut the foam. Due to the suspended weight, the thread remains in a taut position. The load is necessary because the thread begins to sag when heated.
Moving foam is cut with a nichrome thread quickly and evenly. How thick the processed sheets will be depends on the height of the thread above the working surface of the table. The main thing is that the foam is fed at the same speed throughout the entire cutting period.
To cut sheets vertically, you will need to use a cutter of a different design. In it, the cutting wire is stretched in a vertical position. In this case, the work surface is made of chipboard. A frame must be attached to it. It is better if this element is made of metal profile. However, wooden blocks work well.
The frame is equipped with a paw-holder, on which a nichrome wire is suspended. A load is attached to its end. The wire is passed through a hole made in the working surface. So that it does not touch the tree, the hole is protected from the inside with a metal hollow tube.
When using thermal cutters, the foam is not only easily cut into certain blocks. From large plates, various geometric shapes can be cut, such as a square, a semicircle, a triangle. Before work, it is enough to draw a marker over the surface of the plate, marking the cut line.
Curly cutter
When working with foam sheets big size it will be difficult to use a stationary cutter. Such panels are difficult to fit on the desktop. In these cases, a manual foam cutter is used. Such a tool is often made from a jigsaw. The cutting blade in these tools should be replaced with nichrome wire.
Such an electric cutter is quite simple to build with your own hands. To make cutting curly elements more convenient, you can make several devices that have various forms. First, the cutting blade should be removed from the jigsaw, and the wire should be connected to the handle. The voltage will be low, but the handle and other metal parts should be insulated. A nichrome wire is connected to the cable. For this, nuts are used. The wire is bent in a certain way.
A soldering iron can be used as a cutter for curly cutting foam. It needs to be modified a bit. The device already has an electrical wire in its design. To create a foam cutter from a soldering iron, you will need to replace the element that heats up with nichrome wire.
This device is very easy to use. Thanks to this product, it is possible not only to cut material slabs into smaller sheets, but also to make recesses in them.
Metal plate cutter
There is another way to convert a soldering iron into a foam cutter. To modify the tool, you just need to replace the sting with a copper plate. Steel is also suitable, but it heats up longer and is more difficult to sharpen. However, if properly sharpened with a steel plate, it will be possible to cut any synthetics, including foam.
One side of the plate must be carefully sharpened. Sharpening can be done on both sides. It is necessary that the sharpening angle is not too large. The cutting of the material is carried out not only by the blade, but also by the plate blade. Such a cutter has one drawback - you will have to empirically find the optimal temperature for heating the knife.
findings
Building a foam cutter with your own hands is quite simple. The methods listed above will help you understand the device and the principle of operation of the foam cutter. Such devices are practical and easy to assemble. Each method has its own advantages, so home craftsmen can choose the most suitable one for themselves, depending on the materials available.
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