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 be used to cut insulation up to 250 mm thick. You can use a serrated kitchen knife to cut foam. Hacksaw with small tooth We buy it 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, the 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. 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 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:
- workpiece for the 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
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? A more affordable option is to process the 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 foam is the most advanced technology, combining hot cutting tools and precision 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 foam produces a completely smooth cutting surface 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.
Selection of cutting equipment used for foam boards and for extruded polystyrene foam must be conscious. Meet technological requirements for finished products and be economically feasible.
Polystyrene foam is an excellent insulation material. It is used in household and in industry. If you are going to insulate your apartment with polystyrene foam, then you need to know how to cut it. You can use improvised means or a foam cutting machine.
The structure of a machine for cutting foam plastic with your own hands: 1 - frame, 2 - wire, 3 - guides, 4 - foam plastic, 5 - insulating base, 6 - movable guide, 7 - clamping device, 8 - nichrome thread, 9 - clamp, 10 - power cord, 11 - fasteners.
To cut foam, you can use a regular serrated knife. To speed up the cutting process and reduce noise, you need to lubricate the knife blade with machine oil. Cutting foam with a knife requires some effort. This cutting method is the slowest and most unproductive. Cutting speed 1 m in 2 minutes. If the thickness of the material is less than 50 mm, then cutting with a knife is more convenient. To prevent the foam from crumbling, you need to remove the chips with a vacuum cleaner when cutting.
Cutting can be done using a hot string. To do this, you can make your own simple foam cutting machine. You need to hammer two nails into the block, fasten a piece of nichrome wire to them, and then connect a small transformer. Cutting with a hot wire has a high speed: in 10 seconds you can cut 1 m of material. However, this method is harmful to health.
Cold wire slicing involves using the string as a saw with two handles. Gradually the string will heat up from friction, and the cutting speed will increase to 1 m in 50 seconds. You can cut with a hacksaw for metal. This method is more accurate and accurate. The cutting speed is 1 m per 40 seconds.
Cutting using a professional machine is the best, most accurate and fastest. The device for cutting foam plastic includes shaped attachments. When the amount of work is small, you can use a knife.
But if there is a lot of material, then a hot string or a factory-made device for cutting foam plastic is more suitable.
Hand tool for cutting foam plastic RIRP-1
You can cut out facade decoration elements, toys, models of ships or airplanes from foam plastic.
It is most popular among professional builders. This tool performs thermal cutting of material. Using this device, you can make various products, especially if the amount of work is significant. Using RIRP-1, you can cut out façade finishing elements, cut foam plastic for room insulation, and you can also cut various crafts made of foam plastic, toys, models of ships, airplanes. It has high accuracy, speed of work, high strength and reliability.
The time to bring the device into operation mode is 1 minute. It performs thermal cutting using nichrome thread. The diameter of the thread is 0.3 mm - 1 mm. There is an easy-to-use handle in which a nichrome thread is secured using threaded clamps. The nichrome thread used is very durable, will last a very long time and therefore cannot be replaced. RIRP-1 has a filament control unit, which is metal box, in which a single-phase isolation transformer, power regulator, switches, and socket are located. The transformer power is 250 W.
The kit includes:
- RIRP-1;
- device control unit;
- holder on which the nichrome thread is fixed;
- instructions for use;
- passport.
Specifications:
- operating rated voltage 220 V;
- nominal frequency 50 Hz;
- primary circuit current 2 A;
- secondary circuit current 16 A;
- rated voltage 600 V;
- short circuit strength criterion 4.5 kA;
- wire length 2 m;
- length cutting tool 1500 mm;
- external dimensions 155x220x130 mm;
- weight 6 kg;
- warranty period 1 year;
- price 8000 rub.
Manual device for cutting foam plastic RIRP-2
RIRP-2 is a device for thermal cutting of foam plastic and foam rubber. The RIRP-2 device differs from the RIRP-1 device in that it has a rigid cutting element, which is a U-shaped blade. The device is made in the form of a knife. With its help, you can adjust various elements when it is necessary to assemble a product that consists of certain segments.
The material is cut thermally using a blade that heats up. Soft foam is cut very quickly. The dimensions of the blade are 170x18x1 mm. The electrodes of a special holder firmly secure the blade. The set includes 2 blades, working and spare. The service life of the blade is 1 year.
Have you tried cutting foam with a regular knife? It doesn’t work because the material crumbles. I'll tell you how to make a foam cutter with your own hands, and also offer three simple instructions step-by-step assembly cutters for foam and plastic.
What you need to know about cutting foam
Expanded polystyrene is a cellular material, the structure of which consists of many dense compressed bubbles. Bubbles are difficult to mechanically deform, as they can be pressed through even with a sharp knife.
The only way to accurately cut such material is to use a cutting tool heated to a temperature above +100 °C. A lower heating temperature will cause the material under the cutter to sag and tear.
The heating temperature of the cutting tool above +200 °C will cause the edges of the cut to catch fire and burn.
By the way, a properly assembled thermal knife can cut not only polystyrene foam, but also extruded polystyrene foam, polyethylene and other polymer materials.
Assembling a simple cutter from a regular soldering iron
There are situations when foam plastic needs to be cut right now and there is no time to make a complex machine. It is precisely for such cases that I propose a simple way to convert a regular soldering iron into a cutter for polystyrene foam.
The instructions are very simple, and therefore the tool will be ready in 10 minutes, and maybe earlier.
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We prepare materials and tools. We will need:
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We take out the standard tip. Near the tip on the body of the soldering iron there is a clamping screw. The screw must be unscrewed counterclockwise. As a result, the sting will weaken and it can be pulled out. |
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Bend the wire. Bend a piece of wire up to 10 cm long in half. We squeeze the bend with pliers so that the loop on the bend is as small as possible. |
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Cutting the wire. We measure the bent wire along the length of the standard tip and cut it with a small margin. |
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Installing a new tip. We insert the bent and cut wire to the required size into the soldering iron. As a result, the fold should point outward. We tighten the fixing screw and secure the wire in the soldering iron. |
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How to cut? We turn on the soldering iron and wait until the wire heats up. After this, you can use the homemade cutter for its intended purpose.
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Assembling a hand cutter on nichrome thread
Now that you know how to make a simple thermal knife with your own hands from a regular soldering iron, I offer assembly instructions hand cutter with a cutting part made of nichrome wire.
This cutter is as simple as a thermal knife, but it can be used for neat, shaped cutting of foam.
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We prepare everything you need. We will need:
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Attach wooden sticks to the battery pack. Apply hot glue to the edge of the sticks. We apply the sticks to the battery pack, to those walls where the metal terminals are located. |
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Drill holes in the strips for the cable. With a space of 5 mm from the battery pack, in wooden sticks drill a hole. Considering small size sticks, the holes should be no more than 2 mm. |
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We bring out the wire. We pass one of the two wires from the battery pack through the first and second holes to the opposite wooden plank. |
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Attaching the button. We cut off a free piece of wire at a distance of 1 cm from the battery pack. We solder the button to the piece of wire, and on the other side we solder the cut piece of wire. We attach the button to the bar with hot glue and use the same hot glue to isolate the soldering areas. |
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Drill holes for attaching metal strips. In the upper edge of the wooden sticks we drill, at the same distance from the edge, one hole with a diameter of 3 mm. |
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We fasten metal strips and wires. We insert bolts into the holes in the wooden sticks to secure the metal strips. We screw the bare ends of the wires from the battery pack onto the bolts and tighten the connection. |
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Attaching the filament. We stretch nichrome wire into the holes along the edge of the metal strips. We fix the filament between the metal strips using a screw with a nut and washer. We cut off the excess nichrome along the edge with pliers. |
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A device for cutting foam plastic in operation. We install two AA batteries, press the button and cut the foam.
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Assembling a stationary vertical cutting machine
The previous nichrome cutter was held in the hand when working. The model you will learn about now is stationary. That is, the device is stationary, and the foam will be fed manually to the filament.
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Preparing materials. We will need:
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Assembling the bed. From multilayer plywood we cut out a square with dimensions of 70×70 cm. In the middle of the edge plywood sheet screw on a triangular piece of board. We fasten a piece of wooden blocks along two opposite edges of the plywood sheet. We fasten the pieces of timber with a 10 cm indentation from the edge. |
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We make fastening under the lanyard. WITH bottom side frame, between the beams with a distance of 5-7 cm from the edge, screw in a self-tapping screw 2/3 of the way. The head of the self-tapping screw can be used to hook a lanyard. |
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Assembling the mast stand. Using two self-tapping screws, we attach a 50×50 mm block of length 60 cm to a corner pre-fixed on the frame. |
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Installing a crossbar on the mast. At the top of the installed rack, from a 50x50 mm block, we attach a horizontal crossbar 50 cm long. We strengthen the installed crossbar, as shown in the photo, with a diagonal spacer along the inner corner. |
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We determine the point of passage of the wire on the frame. A nichrome filament will run from the top crossbar to the frame. To determine the point of its passage through the frame, we apply a square with an angle to the frame and the opposite part to the crossbar. |
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Drilling the bed. We mark the corresponding point on the bed. Using the mark made, drill a through hole with a 6 mm drill. |
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Preparing the metal plate for the hole. We cut a rectangular plate with a side of 50 mm from millimeter steel. Mark the center of the plate and drill a through hole with a diameter of 2 mm in the center. |
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Installing a metal plate. We attach the plate to the frame so that the holes match. We trace the plate along the outline with a pencil. Using a chisel, we knock out the wood to the thickness of the plate. We put the plate into the recess we made and drive it in until it is flush with the surface of the plywood. |
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Making a crossbar for nichrome wire. Bend a nail 100 mm long in a vice into a “P” shape. We cut off the head and tip with a bolt cutter. |
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Installing the crossbar. On the bottom side of the frame, above the hole into which the wire will pass, we apply a bent nail and mark the legs. According to the markings, we drill holes of a suitable diameter with a depth of 5 mm. Pour a little hot glue into the holes and insert a bent nail. |
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We attach the end of the nichrome wire to the crossbar on the mast. To do this, screw in a screw from the edge of the crossbar, at the point located above the hole in the frame. We wrap nichrome wire around the screw. Tighten the screw so as to press the wire. |
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We connect with nichrome wire top bar and lanyard. We pass the free end of the wire through the hole in metal plate in the bed. We place the wire on the nail crossbar and tie it to the loose lanyard. Scroll the lanyard until the cutting nichrome wire won't stretch. |
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Connecting the power. In our case, we use a battery charger with parameters of 12 V and 4 A. You can use a more powerful step-down transformer and use the secondary winding in it. We connect one cable through the terminals to the bolt on the crossbar, and the second cable to the lanyard at the bottom of the frame. |
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Let's check how it works. Let's try cutting foam plastic. The temperature is sufficient and the foam predictably cuts even better than butter with a knife. |
Let's sum it up
Anyone who has a little free time and a simple tool from a home workshop can assemble a foam cutter. I am sure that the proposed instructions were useful to you, and you will be able to do suitable device. Don't forget to watch the video in this article, you will find a lot of useful information there.
Polystyrene foam is a 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 the 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 plastic must be thin and sharp, but this does not prevent the edge from being destroyed. Even if you work outside, flying small balls litter the environment.
Therefore, professional builders cut foam plastic using nichrome wire or a hot plate. The material is fusible, despite its 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 shapes. 
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.
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, 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). 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 shops 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 from a thick plate required thickness. 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 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 base of the device for cutting foam plastic was a sheet of chipboard (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, wide board, secure the cutting line directly to the work table 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 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 of 0.5 mm less than external diameter racks. 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 in 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. The thickness of the copper wire at a current of 10 A must be taken with 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 to connect a low-power electrical device, for example a 200 W 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 wire The cutter wire will not heat up to the required 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.
