Knife for cutting foam plastic from a soldering iron. Homemade foam cutting machine

Polystyrene foam is durable, lightweight and very good thermal insulation material. It is very easy to work with it. But there are some nuances in working with this material.

Because it is made in the form of slabs large sizes, then very often you need to resort to pruning them. This can be done using a regular knife, but no matter how carefully you try to do it, it will not work.

And all because mechanical impact will disrupt the structure of the foam. That is why experts recommend using only a cutter or, as it is also called, a foam cutter for such actions.

You can, of course, buy such a multifunctional tool, but if you make it yourself, you can adapt it to your needs and, of course, save money.

If you plan to work with a cutter for industrial purposes, then it is still better to buy an electrical device that will be designed for large and frequent loads.

How to do it yourself

The need for a cutter can arise at any time if you do some household chores quite often. Perhaps someone has encountered the need to make a part using a special mold for casting with epoxy resin.

And to do this, you will need a piece of foam. For example, you can use foam from TV packaging. It is necessary to draw on it using a ruler, compass and ballpoint pen the places where holes will need to be made in the future.

This is where the need for an electric cutter comes into play. After all, fulfill given action without damaging the foam sheet, it will be difficult without such a tool. Let's consider one of the options on how to make a device of this type at home.

A homemade cutting device can be various designs. It is on it and the type of cutting that will depend on how exactly the cutter copes with its goals.

Kinds

Before you start making a cutter, you should decide for what purpose you need it, because depending on the purposes, they are divided into several groups:

with metal work plate;
for linear cutting;
for figure cutting.

Stages of creation

Since linear cutting is the most common, let's look at this option in more detail:

Cutting part. To do this you will need nichrome wire, approximately a spiral with a diameter of 0.6 mm. It can be taken from old electric stoves or other heating electrical appliances. The length of such a wire should be 14 cm (its resistance will be 2 ohms).
Transformer application. For everything to be correct, the first step is to calculate the voltage and current for heating the cutting part. This can be done using the formula - Ohm's law I=U/R. Thus, you can determine the power of the power transformer.
Making a cutter. The base can be made of any metal, but its length must be at least 11 cm. Next, an insulator - a PCB plate - must be attached to the end. Now fasten the contact groups along the edges of the plate; they can be removed from the electrical outlet. It is into these contacts that it will be possible to attach spirals of different shapes.
How does the cutter work? After the cutter is plugged in, the wire will heat up and become slightly reddish in color. This is exactly what matters, since a heated cutter will make it possible to easily and quickly cut the foam, which will not peel off.

It is important to know: Having received such a device, in just three minutes it will be possible to cut the required shape from a sheet of foam plastic.

Be sure to follow all safety rules so as not to injure yourself and others. After all, the power of the cutter is enough to damage any part of the body during operation. And connecting to electricity further increases the risk of injury.

Step-by-step production of a thermal cutter

You can make a thermal cutter using a burner or soldering iron and an old jigsaw. Let's consider the manufacture of such a device step by step:

1. Sleeve. Initially, you need to make the main and most difficult thing - the bushing. So, to do this, the plate must be bent and turned. Next, you need to make a hole in the sleeve; the thread will be inserted there in the future.
2. Burner. You need to cut off the wire that leads to the hole, take suitable connectors, then solder it to the break point.

Note: Such areas must be isolated.

1. After everything is done, you can connect the thermal cutter. Cut an old jigsaw in half. IN top part you need to attach the pre-prepared claw plate to the screws. But we attach the bottom to the base using self-tapping screws.
2. Insert the sleeve into the foot. Now, with special attention, you need to use a plumb line or a square to mark the point under the hole of the sleeve from the hole. Next, drill a hole in the base. The diameter of the hole in the base should be about 5 mm.
3. Thermal cutting machine So, when everything is ready, you need to straighten the nichrome wire. To do this, you should turn on the burner at full power and touch the nichrome with the wires from it. Everything must be done in such a way that there is a distance between the wires equal to the height of the device. If the thread does not heat up, but the burner begins to hum, find more thin wire. This is necessary because the one you selected does not have enough resistance.

Take note: nichrome should be hot, but should not get red hot. If the string turns red, you need to reduce its heating using the regulator. In the event that the nichrome is red even at a minimum, then a compensator should be left 5-10-15 cm above the spring of nichrome wire. And only after that you can make contact.

Operation of the device. With a pre-installed guide, you need to cut foam dies to a given thickness, or you can make the shape curly.

Application

If you are making repairs or doing wood cutting, or you need to cut a piece of plywood, then an electric cutter will be very useful for you, which can also be used even for cutting thick fabric.

If you think that for all of the above actions you will only need to use a thermal knife, or a hacksaw will suffice, then you are mistaken.

After all, a hacksaw will not make the edges smooth and not torn, as is the case with a cutter.

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 must be thin and sharp, but this does not prevent the edge from breaking. Even if you work outside, flying small balls litter the environment.

Therefore, professional builders cut foam using nichrome wire or a 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 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.

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 is 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.

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 up 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 take a hacksaw with very fine teeth, but the latter method is very dubious. 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 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.

Foam sheets require cutting and adjustment to size and shape. Every master wants to do this quickly and without unnecessary debris, obtaining a smooth edge that eliminates gaps and cold bridges. By by and large, foam cutting is carried out in two ways - automatic and manual. Of course, at home, for example, to insulate a roof, you won’t need the entire arsenal, but getting to know each other will never hurt. Or maybe it will inspire you to take a new approach to renovation.

Tools for cutting foam sheets differ from each other both in functionality and in the complexity of working with them.

Types and classification of hand tools

Review of the best devices for home use

Professional innovative thermal knife

Such products, as in the top photo, were declared by the Patent Department quite recently - only in April 2010, but, despite their “youth,” they very quickly gained popularity in the market. The main obvious advantage of such a cutting tool is that after cutting PSB of any density, there is practically no debris left in the form of granules.

This device is ready for use immediately after removal from the original packaging, and it takes literally 1-2 seconds to heat up. The handle here is made of lingofol (something like wood, but with higher mechanical strength), and the cutter is made of stainless steel and ceramic. This combination provides a fairly long service life if the breakdown is not done intentionally.

In the top image, there is another option for cutting foam plastic so as not to crumble - this is a homemade unit made from a charger and a string from a piece of nichrome. You can, of course, use unregulated current sources, for example, a battery or charger for cordless drill(screwdriver), but here, of course, the design will lose quality.

In addition to the power source and nichrome, you will need some kind of frame - you can even use a small one coffee table. Fans of figure cutting will appreciate this device.

You can use a hacksaw for metal

It is not always possible to cut polystyrene foam at home with a paint knife or other devices described above due to their absence; for this you can use a hacksaw or a separate blade. Only in this case should you be prepared for the appearance of debris in the form of granules, since PSB consists of them. The teeth, even small ones, will destroy the structure, but if the cutting is done for insulation, then this does not matter from a technological point of view.

Professional laser cutting of PSB

CNC Laser Cutting Machine

Of course, you can use not only a string or a knife to cut foam, but also more modern devices with numeric program controlled. If you do this on an industrial scale, then CNC machines, which are controlled by a computer, are precisely suitable for such purposes. The advantage of such equipment is that an entire workshop of such units can be controlled by just one person from the operator’s cabin.

It is almost impossible to make such a car by hand.

There are different machines, more precisely, software they are given in different ways and in different volumes. That is, older models (they are still being produced, but not in the same quantity) have integrated software, and you cannot change it in the usual way, and in later developments you can independently add certain programs for making three-dimensional figures with the most bizarre and complex shapes.

Various unique shapes made using this method can be used:

in the metallurgical industry for casting certain alloys;
for tuning in the automotive industry;
in industrial construction for the manufacture of formwork, sleeves for insulating pipelines, as well as for pouring any architectural forms;
theater stage decoration;
advertising logos, inscriptions and so on.

Sleeves for insulation of external and underground pipelines

This tool for cutting foam is the most accurate of all of the above, since computer programs, unlike the human eye, do not produce errors. Therefore you get minimal amount waste thanks to the ideal calculation of the area and volume of the figure in relation to the workpiece. There are special programs that, with a little help from the operator, can develop any configurations and transfer them to the machine.

How to make a foam cutter with your own hands

So, you want to find something to use to cut polystyrene foam, but everything in stores is expensive, and a painting knife is not suitable, since it crumbles the polystyrene foam. Make the cutting device yourself, following the instructions.

Preparation of tools and materials

To make your own cutter, you will need:

ampere-volt-ohmmeter (tester);
curly screwdriver;
round nose pliers;
knife or side cutters;
soldering iron with solder;
electrical tape or heat shrink;
polypropylene tube 15-20cm long and 20-25mm in diameter (it is used for water supply);
a piece of insulated wire made of copper, steel or solid aluminum 20-25cm long and 3mm in diameter;
bolt with nut and washers with a diameter of 3-4mm and a length of 15-20mm;
25mm self-tapping screw (preferably with a press washer);
charger 5V;
USB cord for connecting charging to the cutter;
nichrome length 17cm;
a piece of insulated flexible copper wire 50-60cm.

Theoretical preparation and calculations

Now you need to determine the resistance - the net length will be only 15 cm of nichrome, but you always need to take it 1.5-2 cm more so that you have something to twist. When measuring 15cm, you will get 16.8 Ohms, and the charger is 5V, which means I=V/R=5/16.8=0.29A=290mA, that is, the current that will flow through the cutting wire. Charging at 5V has a rated current of about 550mA, that is, almost twice as much - there is more than enough reserve.

Preparation of polypropylene tube and wire

The PPR tube will serve as a handle - this is convenient, since polypropylene conducts heat very poorly, therefore, it will not heat up when the cutter is turned on.

At the end of this tube, with an indentation of 4-5 mm, make a hole for a self-tapping screw, and 60-100 mm from it another hole in order to populate the connection wiring. Bend a thick insulated wire in the shape of the letter P so that the jumper is 15 cm, and at the ends of the verticals make loops (rings) with pliers to fix the nichrome.

Assembling a homemade device

Now you can start assembling the device:

First of all, use a self-tapping screw with a washer to screw the U-shaped holder to the handle, having previously screwed the nichrome and copper wire onto the screw.
Then insert the bolt into the opposite loop, only so that the washers are on both sides - under the head and under the nut, but do not tighten the nut completely - leave some play for connection.
WITH inside screw nichrome between the nut and the washer, and a copper flexible wire from the outside, under the head, and tighten this homemade terminal.
After these steps, the main part of the cutter is ready, but there is still a connection to the power source and laying out the wiring - do not tighten the nichrome too much, but keep in mind that it will lengthen a little when heated.
Wind the far wire onto the contour of the holder, lowering it in this way to the handle, and then insert both (both the far and the bottom) into the second hole in the polypropylene and pull it through the opposite end of the tube. Now all you have to do is connect the device.

Tin the wires and solder the USB to the ends coming out of the tube - the polarity here does not matter at all, just make sure the soldering is strong, since you will hide it in the tube.
Wrap the connections with electrical tape (if there is heat shrink, this is even better) and push this section inside the PPR.
To fix the wire on the handle, you can simply melt the polypropylene with a soldering iron, plugging this end - after 3-5 minutes everything will cool down.

Foam cutter testing

That's it - now connect the USB to the charger, which, in turn, plug into a 220V outlet - heating occurs in 1-2 seconds. Try cutting off a piece of polystyrene foam - you won’t get the usual crumbs that remain when cutting with a knife or hacksaw.

Second option for making a cutter

For the second model, identical tools will be needed, only the materials for making the frame will change - the handle will be made of wood, and the holder will be made of copper without insulation.

Cut the handle with a jigsaw so that it is comfortable for you, that is, “fits your hand,” and at one of its ends, drill a hole to the diameter of the wire and make a hollow for laying.
Then wrap the copper tip with thread (along the length of the groove), insert it into the hole and groove and fill it with some superglue.
Now you can bend the holder in the way that is convenient for you, that is, in height, which will determine the possibility of cutting depth and length, but with the calculation of the power of the charger (carry out the calculation using the formula given for the first option).
Making a loop on the opposite side of the holder can be tricky, especially if you use steel, so just make the cut with a file. Screw a spring with rings at the ends to the handle using a self-tapping screw (one for fixing and the other for nichrome).

Solder the USB - one end to the spring, and the other directly to the holder, after cleaning its surface. Screw the nichrome first to the far end, and then to the spring - this is better for tensioning.
Connect USB to charger and try how to cut foam with such a device.

Now you know how to cut foam plastic and can easily do it with a knife or cutter to prepare slabs for roof insulation. But if you don’t have the skills, it’s better to entrust work on complex instruments to professionals.

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 go beyond bottom side base, and when twisted to the maximum, it provided 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 nichrome wire during adjustment, she could not move arbitrarily, but occupied 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.