Polystyrene foam is a lightweight, durable, good thermal insulation material that is very easy to work with. But it has one unpleasant feature: it is usually made in the form of fairly large slabs, which during operation have to be cut into smaller pieces. No matter how sharp the knife and saw are, they will not be able to accurately cut the slab, since mechanical action destroys the structure of the foam, causing it to crumble rather than cut. Therefore, you need to use a special foam cutter for cutting.
Foam plastic, like any material, requires cutting, which is why you need a cutter.
The simplest homemade foam cutter
This type of cutter is not difficult to make with your own hands. To do this, just take the thinnest guitar string and 4-5 large batteries for an electric flashlight. Having connected all the batteries in series into a single element, you need to connect a guitar string to its ends and secure it with electrical tape, closing the electric arc. Due to the electric current passing through the string, the string will heat up.
Image 1. Diagram of a cutter that allows you to cut flat sheets from a block of foam plastic.
At the point of contact with a string heated to the required temperature, the foam sheet will instantly melt, dividing into two halves, the cut of which will be fused and even. But for normal cutting, the string must be heated to a temperature of at least 120-150º. When working, it will not be difficult to determine whether the string has warmed up enough, since when cutting foam plastic, small stuck pieces will remain on the string. The longer such pieces remain, the lower the temperature of the string. But if they don’t remain on the string at all, then this means that this kind of thermal knife is heated more than necessary.
Such a primitive foam cutter can easily cut 2-3 large layers of material. But with large volumes of work, the batteries run out quickly, so in such cases a cutter powered by electricity is used.
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Options for homemade electric foam cutters
Conventionally, such devices can be divided into groups:
- cutter for linear cutting of foam plastic;
- cutter for shaped cutting of foam plastic;
- cutter with working metal plate.
But despite this division, all cutters have one thing in common.
To make them, you can’t do without a step-down transformer.
Such a transformer must be designed for a power of at least 100 W. Its secondary winding must be designed for a voltage of 15 V and have a winding wire cross-section of at least 1.5 mm.
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Foam Linear Cutting Cutter
Image 2. Diagram of a vertical cutter: 1 – cutting nichrome wire, 2 – weight, 3 – frame, 4 – working surface.
Such devices are mounted from a working surface (you can use a table surface) with two vertical risers attached to it, two insulators attached to the risers, connected to two contacts connected to a step-down transformer and a nichrome thread stretched between the insulators, as well as a freely hanging thread passed through one of the risers cargo (image 1).
This foam cutter works very simply. Passing through a nichrome thread, an electric current heats it, and a suspended weight keeps the thread taut, preventing it from sagging, since when heated it stretches quite a lot. Sometimes, instead of a suspended weight, a spring attached to one of the risers is used to tension the thread.
The heated thread easily cuts the body of the moving foam, turning it into flat sheets, the thickness of which depends only on the distance from the table surface to the tensioned wire. All you need to do is maintain a uniform flow rate of foam across the table surface.
For vertical cutting of layers, a different cutter design is used, in which the cutting wire is stretched vertically (image 2). A frame is attached to a working surface made of thick plywood or chipboard (indicated by number 4 in the diagram), preferably welded from a metal profile, but one made from wooden blocks (3) is also quite suitable.
The design of the frame provides for the presence of a holder-foot, to which a nichrome wire (1) is suspended using an insulator with a suspended load at the other end (2), passed through a hole drilled in the working surface. Since the nichrome thread will heat up, it is better to make the hole larger and insulate the wooden parts by inserting a metal hollow tube of hollow diameter into it, through the cavity of which the end of the wire with the load is brought out.
Such a cutter for foam plastic will not only easily cut large pieces of foam plastic into blocks of the required sizes, but will also allow you, if necessary, to cut squares, triangles, semicircles and other shaped holes in the material. To do this, just first draw a cutting line along the surface of the foam with a marker.
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Cutter for shaped cutting of foam plastic
If you need to cut sheets of large size or thickness, which due to their size cannot be placed on the work table, then in such cases use a manual electric cutter, converted from a hand jigsaw or a hacksaw, in which the cutting blade is replaced with nichrome wire.
Image 3. Diagram of a manual thermal cutter: 1 – nichrome cutting wire, 2 – screw with nut and washer, 3 – textolite handle 4-5 mm thick, 4 – electrical cord.
Such an electric cutter is not difficult to make with your own hands. At the same time, for the convenience of figured cutting, you can make several working tools of different shapes (image 3). The cutting blade of a jigsaw or hacksaw is removed, and an electric wire (4) is connected to the handle (3). Despite the fact that the voltage will not be too high, it is still better to insulate the handle, like other metal elements, at least using ordinary electrical tape. Instead of a cutting blade, a nichrome wire bent as required is attached to the supplied electrical cable using screws, nuts and washers (4).
As an option, you can also use a wood burning device or a pulse soldering iron to design such a cutter. Such a cutter will be even more convenient, since the electrical wire is initially provided for in the design of these devices. To turn these devices into an electric cutter for foam plastic, it is enough to replace the heating working tools in them with a piece of thick nichrome wire, giving it the desired shape.
Such hand-held cutters are convenient because with their help you can not only cut sheets of foam plastic, but also cut out all sorts of recesses and cavities in them, remove chamfers, in a word, not just cut foam plastic into pieces, but sculpt real works of art from it.
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In this article, Danya Kraster, author of the SuperCrastan channel, will show how to make a machine for cutting foam plastic.
Before moving on to the topic of casting, Danya wants to show you a device that will help solve some problems in the manufacture of injection molds. This time we will talk about a foam cutting machine.
Materials and tools.
Kanthal 0.6mm 50cm
Several boards or a piece of chipboard, plywood, for making a table
The beam is hard enough for a barbell, about a meter - one and a half
Steel plate 50*50*1mm
Tarlep
Self-tapping screws
Screwdriver, drills
Chisel.
It’s difficult, in fact, to call this device a machine. Danya would say that this is a device, although in general it is a full-fledged tool.
So, first you need to make a table like this.
4 pieces of wood, 5 screws.
Dan will not show the manufacturing process of this due to dullness, he will show the assembly of the machine itself. Under the table he will have a minimum of problems.
Screw in the self-tapping screw to which the lanyard will be attached. A lanyard is a device used to tension a cable.
Next, he screws a block to the corner and calls it a mast.
A crossbar is attached to the mast on a self-tapping screw.
And he strengthens this matter with another corner made of a block.
The result should be a “gallows” like this.
Use an angled ruler with a stop to mark the place where the filament should go.
In principle, if the table is level, you can do this with a plumb line.
Marks the place X, which is then drilled out with a drill to 6 millimeters.
Next, on a pre-prepared metal plate, 1 millimeter thick, marks the center.
And drills with a millimeter drill.
The plate is needed so that the heated thread during the cutting process does not burn through the wood and does not become loose in all directions. Marks the place where the plate is installed in the table.
The insertion will be flush, and for this you need to select a layer of plywood.
Danya will do this using a regular chisel and a small hammer.
Having cut through the edges, he begins to select the top layer.
After the plate has confidently taken its position and does not catch anything, the author will bend the nails.
And now you’ll understand why. Bends the nail in a vice in the shape of the letter P.
Trims off excess pieces with a bolt cutter.
Next, marks the resulting distance between the “legs” on the underside of the table.
This detail is needed so that the thread does not burn the wood, and so that the lanyard can spin easily.
Drill holes for the bracket using a screwdriver.
Glues the nail-clip onto hot-melt adhesive.
And glues the plate.
For added quality, he presses it down with a hammer.
Next, without worrying too much about fastening the thread, half-screw in the self-tapping screw with a wide head. Commonly known as a bug.
And he wraps a 0.6-millimeter kanthal around it, also known as fechral.
Fortunately, with the spread of vape shops, this material is now super accessible. You can squeeze the bug a little.
Pulls the filament through the hole.
He wraps the kanthal on a lanyard, and attaches the other side of the lanyard to a self-tapping screw.
The lanyard twists in the direction in which it is tightened.
It was perfectly taut, just like a string.
Turns on the power. Dani has a charger for car batteries lying around, so she will use it.
12 Volts, 4 Amps, 40 centimeters 0.6 kanthal. Somehow it happened.
Polystyrene foam is used today in many sectors of construction and industry. With its help, you can arrange thermal and waterproofing, form decorative coverings, baguettes, and much more. The only problem that arises when working with this material is the need for proper cutting. Foam cutting machines can be purchased at the store, but it will be much cheaper to make such equipment yourself.
Manufacturing a structure for cutting foam sheets
In order to get a clean and even cut, you need to use the appropriate equipment. Hot steel can serve as a solution, but using it at home is very problematic. There is only one solution left, which is expressed in the independent production of the machine.
Preparatory work
In order to make a machine for shaped cutting of foam plastic, it is necessary to prepare certain materials and tools. You will need a table that has certain requirements, so each of its sides should not be less than two meters. The master must prepare steel springs that have low current resistance. The work cannot be done without a transformer that is capable of converting current from 220 to 24 volts. A high-resistance string should be used; if you have an old heater, this element can be borrowed from this equipment. The master will also need a string height regulator, which can be played with two beams. The cutting string, which has a holder, will move between them. A transformer may not be needed in every case. This will depend on what material the string will be based on.
Safety of use
If a machine for 3D cutting of foam plastic is made using a chrome-plated string, then a current of 220 volts will be acceptable. But when working with such a discharge, it is necessary to follow safety rules. If you use a 24 volt discharge, there is no danger to life. It will be insignificant. It must be remembered that a foam cutting machine that uses hot steel will operate and release toxic fumes into the air, which indicates the need to use a protective mask. You need to work in a well-ventilated area. It is preferable to carry out cutting work outdoors.
When making a machine for cutting foam plastic, you may not find a table whose parameters correspond to the above. In this case, you can use chipboard, board or plywood as the base. The technology for assembling the machine involves the use of nichrome wire, which must be fixed to the springs, the last of them must be put on screws, and the last of them must be screwed into special racks. Steel stands must first be pressed into the table top. The height of the stand and the thickness of the base will depend on the preferences and needs of the owner. If the thickness of the canvas is 1.8 cm, and the height of the stand is 2.8 cm, then when fully screwed in, the screw will not be able to pass through the canvas. Whereas if you unscrew it completely, it will be able to cut a blade whose thickness is 5 cm.
Changing machine parameters
When making machines for cutting foam plastic, it is necessary to take into account the fact that in the future there will be a need to cut thicker sheets of materials, while short screws can be unscrewed and longer ones installed in their place. In order to press in, you need to make a hole in the base. Its diameter should be less than this indicator characteristic of the rack, the difference should be 0.5 millimeters. When making machines for cutting foam plastic, the racks need to be driven into the holes with a hammer, but to facilitate the procedure, it is necessary to process the sharp edges of the ends with sandpaper. Before you start screwing the screw into the rack, you need to cut out a groove under its head. In order to do this, you need to clamp its end with a screwdriver, while a thin file should be placed under the head, and then rotate. The groove is necessary in order to strengthen the wire in one position, which can move during adjustment. In order for the wire not to sag, elongating after heating, it must be fixed to the springs, and then to the screws. When making machines for cutting foam plastic, you need to prepare all the fasteners, and then strengthen the nichrome wire. In order to ensure reliable contact between it and the current-carrying wire, you need to use a technology called “unwinding with crimping”. The copper wire must have a cross-section of at least 1.45 sq. mm.
Final works
At the next stage, you need to remove the insulation from the end of the wires by 2 centimeters. Copper conductors must be wound onto the wire in those areas where it is fixed to the spring. The end of the wire should be held with pliers and then wrapped around the conductor. In order to ensure the possibility of adjusting the cutting thickness of the blade, it is necessary to make a tap of the current-carrying conductors. To prevent sagging of the wires, you need to make a hole in the base through which a segment is passed and fixed on the back side of the surface using staples. If you will be cutting foam plastic, you can easily make a machine with your own hands. During the process, the wires should be folded together in the form of a bundle, this will prevent them from becoming tangled. The ends of the wires need to be secured with terminals so that they can be connected to a power source.
Finally
If you decide to make a CNC machine for cutting foam yourself, then it will be quite enough for you to use at home, unless you are going to set up a production line. The speed of the blade when cutting should not be too high. If the motor runs very fast, then this will cause the material to crumble. This cannot be allowed in any way, since in this case it would not be advisable to manufacture and use an automatic type machine. After all, to carry out the work you will still have to spend a certain amount of effort and time. This must be taken into account when choosing the components of a future design.
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 affordable methods of insulation.
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 an electric grinder, you shouldn’t expect 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 a 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, in front of you, which you built for your large family, then the question of how to conveniently cut the foam, 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 will provide detailed instructions on what and how to do.
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 a universal material with uniquely high sound-absorbing and heat-insulating capabilities. For this reason, it is often used to insulate residential buildings. If desired, foam plastic can be cut into blanks of any size at home. Let's see how it's done.
How to cut polystyrene foam at home?
Thermal insulation of private houses and apartments can now be done with a variety of materials. At the same time, foam plastic has remained one of the most popular insulation materials over the past decades, due to its affordable cost, low weight, and resistance to alkalis, weak acid solutions, and water. The material we are interested in does not change its properties for a long time. It is not afraid of high (up to 90 °C) temperatures, is characterized by good mechanical strength, high noise absorption and low thermal conductivity. Pockets of bacteria and fungus never appear on it.
Polystyrene foam is famous for its environmental safety (it is made from styrene, which is recommended for the production of food storage containers) and fire resistance (it does not smolder when exposed to fire). Construction stores sell it in sheets. The thickness of the latter varies between 10–100 mm. Many manufacturers also produce polystyrene foam to order. The thickness of such products can reach 500 mm. When installing, foam plastic has to be cut into blanks of certain sizes. This is not as easy to do as many home craftsmen think when faced with a similar task for the first time. Cutting foam plastic has many nuances and tricks. If you deal with them, the process of cutting the material will take a minimum of time.
At home, cutting the described insulation is carried out using:
- various types of knives;
- soldering iron with a special nozzle;
- strings;
- hacksaws for wood;
- Bulgarians;
- homemade machine.
Next, we will describe in detail the tools and devices used for cutting foam plastic, and consider the advantages and disadvantages of their use. And then any self-taught master will be able to decide for himself which cutting method suits him best.
We use hand tools - not ideal, but an acceptable option
If the foam sheets have a minimum thickness (10 mm), it is quite possible to cut them with a simple stationery knife. There is one peculiarity here. When cutting a large number of workpieces, the knife will become dull. Because of this, the foam will begin to crumble around the edges. It will be impossible to achieve an even cut in such situations. It is not difficult to avoid such a problem. You just need to warm up the tool a little before cutting the next sheet.
It is better to work with products with a thickness of 20–40 mm using a shoe knife. But only on condition that its edge is dull and the blade itself is very well sharpened. Important! A shoe knife should be sharpened very often. We made 3-4 cuts. They took the sharpener. The sharpness of the blade was restored. We continued cutting. Significantly fewer problems arise if you use a special knife for working with foam plastic. At the end of such a tool there is a rubber nozzle.
The special knife cuts workpieces quickly and accurately. But working with him is dangerous. There is a possibility that the tool will slip off the workpiece and injure a person. Reducing possible risks is not difficult. It is enough to secure the foam sheet in a vice. And only after that cut it. Note! The knife should always be moved away from you. This also reduces the risk of injury.
Another special tool – a thermal knife – also provides high-quality cutting. It is a soldering iron with a nozzle. This device heats up during use, which allows you to cut material without any physical effort. When working with a thermal knife, you must be extremely careful. When heated strongly, it will begin to melt the foam. Drops of the latter can get on the master's hand or on his clothes.
Thick sheets (80–100 mm) can be cut with a fine-toothed hacksaw designed for cutting wood.
Foam plastic can be easily processed with such a tool. But this method is only suitable for cases when we need to get a straight, long cut. We will not do figured cutting of products using a saw. Large sheets can also be cut with a grinder. You just need to put a metal disc of minimal thickness on it. The disadvantages of the technique are the loud noise from the grinder and the squealing from the material being cut, as well as a large amount of debris. Pieces of polystyrene foam will fly all over the room. Collecting them will subsequently take a lot of time.
Homemade machine - cuts sheets of any size and thickness!
The most effective way to cut foam plastic involves using nichrome string (wire). It provides high productivity of the operation and almost complete safety for the master. In order to use the string, we need to build a simple stationary cutting machine. To make it we will need:
- nichrome thread (wire);
- old table;
- rheostat;
- drill;
- spring;
- electric wires;
- M24 screws;
- transformer;
- metal rod.
Nichrome wire is easy to obtain. It is used in a variety of heating household appliances (electric kettles, water heaters, irons, stoves, hair dryers, air heaters, and so on). We simply find a broken device and take out the thread we need from it. You cannot use regular steel wire. Nichrome is a combination of nickel and chromium, which has great mechanical strength and high electrical resistivity. It is optimal to use wire with a cross section of 0.6–0.8 mm. It can easily cope with cutting all standard thickness foam sheets.
The diagram for making a machine with your own hands will be as follows. We make the tabletop from wide boards, plywood sheets or chipboards. If the household has an old unnecessary table, we use it to create the base of a homemade machine. We drill two holes at a distance of 0.2 m from each edge of the tabletop (we place them along the center line of the structure). We insert screws into them from the reverse side. Instead of these hardware, you can install two racks made of a metal rod. We fix the screws with nuts.
Next, we fix the nichrome string on one of the racks (it should be at a height of 10 cm from the surface of the tabletop). We mount a spring on the second support. We fix it securely. Attach the second end of the wire to the spring. This complicated string installation scheme is due to the fact that the nichrome thread will expand when heated. This will cause it to sag, which will complicate the process of cutting the foam. If the thread is attached to a spring, the latter will compensate for the expansion. This precaution will eliminate the possibility of the cutting wire sagging.
The next step is to connect the electrical wiring to the racks. Nuance! We connect the wires from the bottom of the tabletop. Then, when using the machine, they will interfere with the movement of the foam sheets being cut. Then we connect the wires to the transformer (LATR). The homemade machine will be connected to the network through it. We take any transformer. The main thing is that it can withstand a load current within 8–10 A. We place the LATR under the tabletop. We turn on our machine. We begin to cut out the foam using nichrome. We apply a sheet of material to the string and lightly press on it. We get a perfectly even cut.
Important addition. Experienced craftsmen advise equipping a homemade machine (its transformer) with a rheostat. This elementary device will make it possible to select the optimal amount of current supplied to the cutting device, due to which we will be able to regulate the temperature of the nichrome string. The presence of a rheostat simplifies the cutting process and also extends the operating time of the transformer.