DIY crucible furnace. DIY graphite crucible Homemade crucible for melting gold

To melt metals, special heat-resistant bowls called crucibles are used. They are very popular in jewelry workshops, laboratories and the metallurgical industry. But for a full-fledged process, it is not enough to acquire a simple object with a heat-resistant surface, because different types of iron require their own product, which must comply chemical composition and fit a specific temperature regime. These facilities also produce a finished alloy, which remains to be given the correct shape.

Sometimes it happens that such devices may be needed in private business, but purchasing them is expensive. Therefore, it is more profitable to make a crucible with your own hands - you can save a significant share of the budget. Yes, the procedure will require certain skills and patience, but in the end you will get a vessel that is not inferior to factory analogues. It is also important to decide on the types of objects to be melted in order to make a suitable bowl. If you plan to work with different metals, it is recommended to create several products.

As an alternative, you can use an electric crucible, which you can do yourself without much difficulty. It has several uses, but the main one is gold refining.

General manufacturing steps

To begin with, the raw materials are prepared, and here everything depends on the model of the future tank. It is better to take components with a reserve, because the first thing is unlikely to work out. Also, for safety reasons, production should be carried out away from open fire, and choose a well-ventilated area.

It is safer to carry out work in a garage or special extension.
The second stage is mixing the materials and giving the casting the necessary parameters. For these purposes, plaster molds are used. Creating the outlines is not difficult, and such information is easy to find on the Internet. Then a homogeneous material is pasted over the outer part of the model, forming a future homemade refractory crucible. It is also important to give it the required depth and thickness.
And the last step is the drying process: the workpiece is placed in cardboard box and cover with a lid. This will allow the casting to dry and remove excess water from it. Sometimes it may be necessary heat treatment However, the most important point is to control the annealing temperature and protect the skin of the hands and face. If the heat is too intense, the item will burst and there is a chance of severe burns. Detailed instructions How to make a crucible yourself and at home will be discussed in the following chapters.
Making a clay crucible
Here you can’t do without fireclay clay, which is sold in any building materials store. It tolerates extreme thermal effects very well, is cheap, and there are unlikely to be any problems finding it. As a last resort, you can make a crucible from crushed fireclay bricks. You will also have to buy liquid glass and mix all the ingredients for a homogeneous base. The proportions look something like this:
7 units of clay;
3 units of fireclay;
10 spoons liquid glass.

All components are added in stages: clay and fireclay are mixed until smooth, and water is gradually added to them. The main goal is to create a mixture that will not stick to your hands. When the required consistency is obtained, glass is added and everything is thoroughly mixed. The main thing here is to bring the object to a state where the plane stops cracking. The mixture is ready, and for storage it is recommended to use thick cellophane, or wrap it in 7-10 layers of film.
Before sculpting, you will have to remove any remaining air by hitting the substance about 8-12 times on a hard surface.

The mixed material is applied inside the model, its depth and thickness are formed. It is better to create a semicircular bottom, which will give a greater effect during future melting of iron filings. Also, the substance must be pressed tightly against the model so that air does not form between the planes, and for greater convenience it is recommended to wet your hands with water.
Afterwards, the tank is sent for drying: it is placed in a container made of cardboard or plastic and placed in a dry place. A few hours will be enough to remove any remaining moisture. Also, the product will settle a little, and it will be easy to remove it from the mold. A refractory vessel made of fireclay bricks will last for a long time of use, however, the last point of creation should be the firing procedure in a furnace and at T = 800 °C. And the thing can be used for its intended purpose. For ease of use, you will need a crucible furnace, which you can make yourself. For easy installation you can weld a structure of several pipes to form a cylinder. Usually it is fixed on two parallel posts so that it does not touch the ground. And here the thickness of the walls (minimum 5 mm) and the stability of the product are taken into account (it must easily withstand T = 1600 °C or more).
How to make a graphite crucible
low overall weight;
resistance to hot alloys;
good thermal conductivity;
strength increases with increasing temperature.

If you take the easy route, you can take graphite rod, and the crucible is almost ready. All that remains is to attach the bottom.
If the required tube is not found, everything can be done using two molds different sizes, which are inserted one into one, and the free space will allow you to add required sizes. Initially, you need to pour the mortar into an empty container, and you should not spare it. The fact is that the powder will compact and settle. Next, add liquid glass (about 15 ml) and mix everything thoroughly. It is recommended to place the mixed mass in a large cylindrical container (you can use a plastic cup) and press a hole into a small one, leaving the bottom thick enough.
As a result, a vessel will come out, which is given time to dry. In this case, heat treatment will also be required to remove excess liquid. If all the steps were correct, then you will have a high-quality graphite crucible, made by yourself.
Assembling a cast iron crucible
This type is the worst, but sometimes it brings good benefits. All that is required is to place a cast iron glass of a smaller diameter in a metal bowl, and fill the free space with sand and clay.
Next, everything is heated in the oven until the mixture melts and takes on the same type of substance. Afterwards, the cup will harden, and iron can be melted in it. This is the basic information on how to make a crucible at home and with minimal costs.

To melt metals, special heat-resistant bowls called crucibles are used. They are very popular in jewelry workshops, laboratories and the metallurgical industry.

But for a full-fledged process, it is not enough to acquire a simple object with a heat-resistant surface, because different iron requires its own product, which must correspond to the chemical composition and be suitable for a specific temperature regime.

Also, these facilities produce a finished alloy, which remains to be given the correct shape.

DIY crucible

Yes, the procedure will require certain skills and patience, but the end result will be a vessel that is not inferior to factory analogues. It is also important to decide on the types of objects to be melted in order to make a suitable bowl.

If you plan to work with different metals, it is recommended to create several products.

Steel crucible DIY crucible for lead

Material selection

Here, fire-resistant components play a serious role, which include:

Ceramics – middle option, perfect for personal use. There are no reactions that can change the structure of the metal in this cookware, and it is excellent for cobalt, chromium and palladium.
Clay is a substance that is used in the production of crucibles for jewelers. This component is highly fire-resistant and can withstand up to +1600 °C. If a person wants to create jewelry in own premises, but doesn’t know what to make dishes from for melting, then this option is definitely the best.
Graphite is excellent for melting galvanized and brass alloys, and its main advantage is durability. Regarding operating temperature, then it should not exceed +800 °C.
Cast iron. Crucibles made from this substance are rare and belong to the budget categories. Also, products of this kind will have disadvantages in the form of rapid oxidation, low heat resistance and fast production (up to 30 heats).

Varieties of homemade crucibles

As an alternative, you can use an electric crucible, which you can do yourself without much difficulty. It has several uses, but the main one is gold refining.

General manufacturing steps

To begin with, the raw materials are prepared, and here everything depends on the model of the future tank. It is better to take components with a reserve, because the first thing is unlikely to work out. Also, for safety reasons, you should carry out production away from open fire, and choose a well-ventilated area.

It is safer to carry out work in a garage or special extension.

The second stage is mixing the materials and giving the casting the necessary parameters. For these purposes, plaster molds are used.

Creating the outlines is not difficult, and such information is easy to find on the Internet.

Then a homogeneous material is pasted over the outer part of the model, forming a future homemade refractory crucible. It is also important to give it the required depth and thickness.

Clay crucible in the drying process

And the last step is the drying process: the workpiece is placed in a cardboard box and covered with a lid. This will allow the casting to dry and remove excess water from it.

Sometimes heat treatment may be required, however, the important point is to control the annealing temperature and protect the skin of the hands and face. If the heat is too intense, the item will burst and there is a chance of severe burns.

Detailed instructions on how to make a crucible yourself and at home will be described in the following chapters.

Making a clay crucible

Here you can’t do without fireclay clay, which is sold in any building materials store.

It tolerates extreme thermal effects very well, is cheap and there are unlikely to be any problems finding it. As a last resort, you can make a crucible from crushed fireclay bricks.

You will also have to buy liquid glass and mix all the ingredients for a homogeneous base. The proportions look something like this:

7 units of clay;
3 units of fireclay;
10 spoons of liquid glass.

Clay crucibles

All components are added in stages: clay and fireclay are mixed until smooth, and water is gradually added to them. The main goal is to create a mixture that will not stick to your hands.

When the required consistency is obtained, glass is added and everything is thoroughly mixed. The main thing here is to bring the object to a state where the plane stops cracking.

The mixture is ready, and for storage it is recommended to use thick cellophane, or wrap it in 7-10 layers of film.

Before sculpting, you will have to remove any remaining air by hitting the substance about 8-12 times on a hard surface.

The mixed material is applied inside the model, its depth and thickness are formed. It is better to create a semicircular bottom, which will give a greater effect during future melting of iron filings. Also, the substance must be pressed tightly against the model so that air does not form between the planes, and for greater convenience it is recommended to wet your hands with water.

Afterwards, the tank is sent for drying: it is placed in a container made of cardboard or plastic and placed in a dry place. A few hours will be enough to remove any remaining moisture. Also, the product will settle a little, and it will be easy to remove it from the mold.

A refractory vessel made of fireclay bricks will be enough for a long time of use, however, the last point of creation should be the firing procedure in a furnace and at T = 800 ° C. And the thing can be used for its intended purpose.

For ease of use, you will need a crucible furnace, which you can make yourself. For simple installation, you can weld a structure from several pipes to form a cylinder. Usually it is fixed on two parallel posts so that it does not touch the ground.

And here the thickness of the walls (minimum 5 mm) and the stability of the product are taken into account (it must easily withstand T = 1600 °C or more).

How to make a graphite crucible

low overall weight;
resistance to hot alloys;
good thermal conductivity;
strength increases with increasing temperature.

If you take the easy route, you can take a graphite rod, and the crucible is almost ready. All that remains is to attach the bottom.

Graphite crucibles in various sizes

If the required tube is not found, everything can be done using two molds of different sizes, which are inserted one into the other, and the free space will allow you to give the desired dimensions. Initially, you need to pour the mortar into an empty container, and you should not spare it.

The fact is that the powder will compact and settle. Next, add liquid glass (about 15 ml) and mix everything thoroughly.

As a result, a vessel will come out, which is given time to dry. In this case, heat treatment will also be required to remove excess liquid. If all the steps were correct, then you will have a high-quality graphite crucible, made by yourself.

Assembling a cast iron crucible

This type is the worst, but sometimes it brings good benefits. All that is required is to place a cast iron glass of a smaller diameter in a metal bowl, and fill the free space with sand and clay.

DIY cast iron crucible

Next, everything is heated in the oven until the mixture melts and takes on the same type of substance. Afterwards, the cup will harden, and iron can be melted in it. This is basic information on how to make a crucible at home and at minimal cost.

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Source: http://StankiExpert.ru/spravochnik/materialovedenie/tigel-svoimi-rukami.html

Melting furnaces: types and design of crucibles, making a crucible with your own hands from graphite, clay or cast iron

Almost every item has several types and purposes, including stoves.

There are stoves for heating rooms and for cooking food, and there are special devices for melting metals or storing them in molten form. Such devices are called crucible melting furnaces.

They have a specific purpose and therefore the list of enterprises where they have found their application is quite small. These are mainly factories and laboratories.

But what to do if you need to melt metal for some purpose at home? It is very expensive to buy such equipment, but it is quite possible to make it yourself. This requires minimal knowledge in this area, desire and time.

A crucible furnace is a container made of refractory material in which metal is heated to a certain temperature. The main materials from which crucibles are made:

Used crucible furnaces like in factories where more are produced hardware, and in small enterprises, for example, for the manufacture of jewelry.

Ceramic ovens are best option. When metals are melted in a ceramic crucible, no changes occur in the substance itself. Therefore, in such crucibles there are no problems Even base metals or alloys can be melted from cobalt, chromium or palladium.

Graphite crucibles.

These ovens are different for a long time operation and high resistance to oxidation, which makes them universal for melting any metals and especially alloys based on zinc and brass. In addition, they are often used in induction furnaces. Graphite crucibles can withstand very high temperatures, such as eight hundred degrees to melt aluminum.

Cast iron crucibles are perhaps the worst of the three listed. They have high reactivity, rapid oxidation and interaction with other metals, and cast iron does not resist high temperatures well. For these reasons cast iron crucibles are very rare, but they are inexpensive and quite accessible.

This article will look at methods for making three types of homemade crucibles.

Crucible furnaces

The heating element of the crucible arm at home is usually an inductor. He has cylindrical shape with a cavity inside. A homemade crucible with metal shavings is placed in this cavity.

Inductor made of fireproof material, inside it is a winding of wire, most often copper wire is used.

Using a special generator, current is supplied to this winding, which creates an electromagnetic field. Which, in turn, creates an eddy current in the crucible and in the metal placed in it. They melt the chips.

The inductor itself is assembled from 4 vacuum tubes with a parallel connection. Such an inductor can be connected to a regular outlet.

There is another option for assembling an inductor with your own hands from an electromagnetic core and two layers of winding. First layer – 10 turns copper wire with a thickness of 4 mm, and the second is one turn, the material for which is a metal plate with a cross-section of 15 * 5 millimeters.

The electromagnetic core has U-shape and is a set of steel plates. The first winding is made around the plates, which is placed in an insulated housing, the secondary winding connects the core and metal bars, between which there should be a distance equal to the dimensions of the crucible.

This entire structure is placed in the furnace body.

So, we get a furnace in which the inductor is located. Wires go from the inductor to the socket. A crucible is placed in this furnace in such a way as to enclose the bars.

If it is placed correctly, a buzzing sound will be heard, indicating that tension has appeared and melting has begun.

If there is no sound, then use the handle to move the crucible until the circuit is completely closed.

Making a crucible from clay

You can make a crucible from fireclay clay. This inexpensive option and also highly resistant to high temperatures. like this clay is used for laying stoves and it can be bought at any hardware store. Fireclay clay can withstand temperatures up to 1600 degrees Celsius.

So, you will need fireclay clay (sold in bags in construction stores), liquid glass (sold there) and ground fireclay. It can be bought or made from fireclay bricks.

In order to make a mixture from which a crucible will be fashioned in the future, take 7 parts of clay, 3 parts of fireclay and 10 tablespoons of liquid glass per liter of dry mixture. Fireclay and clay are mixed until smooth.

After this, water is slowly added. To avoid spoiling the workpiece You can add some of the mixture, and in the case large quantity water - add dry powder.

You need to knead until the clay stops sticking to your hands.

Only after the clay of the desired consistency has been mixed can glass be added. When adding glass you need to mix everything thoroughly until the clay stops cracking.

It is best to add glass to a lump of clay and roll it into a roll, then fold it several times and repeat the procedure until it stops cracking. The material for the crucible is ready.

Until it is used, it must be stored in several layers of cellophane.

There is clay, now to make a crucible you need to take a mold, the easiest way is to use a plaster mold. How to make such a form can be found on any website on plaster modeling. So, directly making the crucible.

Before you start sculpting, you need to knock all the air out of the clay; to do this, you can lay a newspaper on the floor and forcefully throw a lump on it several times, ten times will be enough.

Now take a lump of clay and carefully press it into the bottom of the mold, after which the walls of the product are formed in small lumps. Their thickness can be controlled along the edge of the mold. Very it is important to carefully press the clay into the mold so that no air cushions form there.

After the crucible is sculpted, you need to make the inner surface smooth. To do this, just moisten the clay with water.

After this comes the moment of drying. The mold with clay is placed in a cardboard box and covered with a lid. After seven hours, all the water from the clay will evaporate and the shape of the future crucible will “shrink” a little, so getting it out of the mold is not particularly difficult.

After this, the crucible continues to dry in the same box; as it dries, all defects will be eliminated by themselves and the pot will acquire a gray color. Sometimes small cracks may appear. They can be covered with wet clay.

Graphite is a material that has many unique properties. Positive qualities graphite:

resistance to molten metals;
increase in strength with increasing temperature;
high heat resistance and thermal conductivity;
small specific gravity.

To make a crucible from this material you will need:

graphite powder;
solid graphite;
felt;
graphite tube;
fireclay mortar;
magnesite.

Some of these materials can be used as independent units. For example, a graphite tube is essentially already a crucible; you just need to make a bottom in it.

The principle of manufacturing from all materials is the same. Let's look at the example of mortar. Two forms are made. You can roll it out of thick paper to make it easier to remove later. External the shape has the configuration of a hollow cylinder, and the inner one is just a cylinder. The small cylinder is inserted into the wider one.

The mixture will be poured between them. The mold is placed in a plastic cup and mortar powder is poured into it. You need to fall asleep with a slide, as it will sit down when you need to compact it. 15 cubes of liquid glass are poured into this powder using a syringe. Everything is mixed and the consistency of shortcrust pastry is obtained.

Stuff into the mold in small portions.

The result is something like a glass turned upside down. To prevent the form from sticking to the table, it is best to do the entire procedure on cellophane.

Then the mold is turned upside down and the inner cylinder is removed. It is also best to initially glue it with cellophane or tape.

Then, when removing, the shape of the crucible will not be damaged.

After the crucible has dried, it must be placed in the inductor and heated.

This is necessary do at low temperatures, since all the water should evaporate, despite the fact that outwardly it seems as if it is not there at all.

If the crucible is not preheated and you immediately start melting in it, it will most likely burst. After warming up, when you tap the crucible, it will make a ringing sound. This indicates that the crucible is well made.

By following the instructions presented, you can quite easily acquire a homemade melting furnace that will last no less than a purchased one. The main thing is to take your time, be careful in your work and not violate manufacturing technologies.

If you are going to do aluminum casting at home, then you will need not only the muffle furnace itself, but also a crucible for muffle furnace. The good news is that all of this can be made very easily and at minimal cost. When I did and described the process in my Dimanjy TechnoBlog, I actually ended up with 0 rubles, because... all the materials were lying around and rusting near the barn, eager to end up in a landfill, and only mother laziness saved them from such a pitiable fate.

I also made the crucible for the muffle furnace myself from a regular piece of thick-walled pipe suitable diameter. But, as I later learned on the ChipMaker forum, I was a little hasty. And here's why.

The easiest way to make a crucible for a muffle furnace is to weld it from metal, or rather from a piece of pipe. But the fact is that the design of my muffle furnace is equipped with open conductive heating elements. And how come I didn’t get electrocuted during my first melting of aluminum at home! Intuitively, I very carefully inserted and removed the crucible from the working chamber of my muffle furnace. By the way, it is often called a “crucible furnace” precisely because non-ferrous metal is melted in a crucible. Now I need to modify the design of the stove, providing it with a special lid with an opening sensor, the signal from which would turn off the electricity from the heating elements, saving me from electric shock. But that’s not about that now.

As I said, making a metal crucible is very simple. We take a pipe of suitable diameter. It is very desirable to have a wall thickness of at least 4-5 mm, otherwise a thinner-walled crucible will quickly burn out, and during the melting process, liquid aluminum may flow out of the crucible, thereby short-circuiting the exposed spirals of the heating elements of the muffle furnace. To prevent this from happening, you can drill a drainage hole in the bottom of the muffle furnace. Then all the aluminum will flow out through it, burning our heels, but saving our mini-smelter from failure. By the way, this was also advised to me on the forum. I didn't think of this myself.

So, we take a pipe, clean it and weld it at one end with a metal plate, which we then lightly file with a grinder to give it a more or less rounded shape.

You can, of course, not clean it up. Then it will all burn out on its own. working chamber muffle furnace, but I didn’t really want to breathe in all this afterwards, so I wasn’t lazy and polished

Then we saw off the pipe so that we get a glass required height- this will be our crucible.

As you can see from the picture, I attached a spout to my crucible and ground it a little with a grinder and polished it with a file. The spout is also very easy to make - it’s a piece cut at an angle metal corner. At what angle to cut - you can guess for yourself. Twist the piece of angle in your hands, mentally drawing the cutting plane of the angle grinder through it.

I also welded an M8 nut to the opposite side of my crucible. A handle is screwed into it for immersing and removing the crucible from the crucible furnace. Just a few turns of the handle are enough, and our crucible holds tightly, eliminating accidental tipping or spilling molten aluminum into your slippers. Such safety measures are especially relevant for melting non-ferrous metals at home.

I made the handle from an ordinary piece of reinforcement, welding an M8 bolt on one side. The only drawback of such a crucible handle is the inconvenience of casting. But this can be easily corrected by welding an additional device onto our crucible so that it is convenient to intercept. When I do this I will update the post. Follow the updates on TechnoBlog Dimanjy

Date: 04/30/2018
Category: Magic tools, weapons, devices and armor - Mod Thaumcraft 3, 4, 5, 6
Views: 2455

How to create

To create this device we will need a regular boiler. We take the magic wand in our hands and press RMB, pointing it at the cauldron. I would like to note that in Thaumcraft 3, when using a wand, 25 vis will be spent, and in Thaumcraft 4, in turn, any wand will do and no units of magic will be spent from it.
Now we will need to pick up a bucket and fill it with lava. Since fire and lava are sources of heat for the crucible. In version 4 of Thaumcraft, you can also use Nitor or flowing lava.
In Thaumcraft 4.1 you can improve the crucible using Thaumotory, now the tool does not require water. But note that it needs warmth.
All that remains is to dig a hole and pour lava into it. It will not be possible to place a cauldron directly on the lava; place any block nearby and place the cauldron. It all roughly looks like this:

Usage

First, pour water into it (take a bucket of water in your hands). The water in the crucible should boil after certain time due to the heat source. Using the thaumonomicon, you now need to find out the necessary aspects for the item you need or to carry out transmutation, after which you will need to throw the items with aspects into boiling water. Further actions depend on the version of the mod.
In Thaumcraft 3, to get a craftable item you will need to use a magic wand with the right amount charges. If you throw more aspects into the crucible, an equal number of objects will be created or transmutations will be carried out.
In Thaumcraft 4, after you throw aspects into the cauldron, you need to throw in the main ingredient (catalyst) and if there are enough aspects in the crucible to complete the reaction, then you will receive the desired item. For example, to get nitor, you must add the following aspects to the cauldron: Lux, Potentia and Ignis (3 pieces each), and the main ingredient will be glow dust. As long as there are enough aspects in the cauldron, each glow dust thrown will allow you to get a new nitor. If at least one aspect is missing, then the decomposition of light dust will begin.

Important: Essences in Thaumcraft 4 tend to degrade quickly, so we do not recommend loading a huge amount of essences for mass crafting in order to avoid contamination, spoilage and pointless waste of essence. Degrading the essence will make the process of crafting the item impossible or difficult. For example, Lux can turn into Aer or Ignis. The time after which this process will begin is 5-10 seconds.

Improvement

You can “upgrade” the crucible's functions using auxiliary elements in the game. In Thaumcraft 3, you can add up to 4 stills to the crucible (by pressing RMB). They are needed to collect unnecessary aspects for operations.

In Thaumcraft 4, you can add mystical fur to the crucible to speed up the boiling process of water. In this version, distillation cubes are not added, but an alchemical furnace is used to separate the essences.

Features and facts

If the player somehow stands on the crucible, he will begin to receive damage in the form of half a heart, at which time the “Corpus” aspect will automatically be added to the crucible.
If you put on the "glasses of revelation", you will be able to see all the aspects that are in the crucible. They will appear above the crucible.
When you hold down the “Shift” key and RMB on the crucible with a magic stick, all aspects contained in it will turn into an aura, while at the same time turning into damage. If there are stills next to the crucible, then the aspects will go there. Well, if all the aspects do not fit into the cubes, then the remaining ones will turn into damage.

Almost every item has several types and purposes. This truth also applies to ovens.

There are stoves for heating rooms and for cooking food, and there are special devices for melting metals or storing them in molten form.

Such devices are called crucible melting furnaces. They have a specific purpose and therefore the list of enterprises where they have found their application is quite small. These are mainly factories and laboratories. But what to do if you need to melt metal for some purpose at home? It is very expensive to buy such equipment, but it is quite possible to make it yourself. This requires minimal knowledge in this area, desire and time.
A crucible furnace is a container made of refractory material in which metal is heated to a certain temperature. The main materials from which crucibles are made:
- ceramics;
- graphite;
- cast iron.
Crucible furnaces are used both in factories where metal products are manufactured, and in small enterprises, for example, for the manufacture of jewelry.
Ceramic stoves are the best option. When metals are melted in a ceramic crucible, no changes occur in the substance itself. Therefore, even base metals or alloys of cobalt, chromium or palladium can be melted in such crucibles without any problems.
Graphite crucibles. Such furnaces are characterized by a long service life and high resistance to oxidation, which makes them universal for melting any metals and especially alloys based on zinc and brass. In addition, they are often used in induction furnaces. Graphite crucibles can withstand very high temperatures, such as eight hundred degrees to melt aluminum.
Cast iron crucibles are perhaps the worst of the three listed. They have high reactivity, rapid oxidation and interaction with other metals, and cast iron does not resist high temperatures well. For these reasons, cast iron crucibles are very rare, but they are inexpensive and quite accessible.
This article will look at methods for making three types of homemade crucibles.

Crucible furnaces. Inductor assembly
The heating element of the crucible arm at home is usually an inductor. It has a cylindrical shape with a cavity inside. A homemade crucible with metal shavings is placed in this cavity. The inductor is made of fire-resistant material, inside it there is a wire winding, most often copper wire is used. Using a special generator, current is supplied to this winding, which creates an electromagnetic field. Which, in turn, creates an eddy current in the crucible and in the metal placed in it. They melt the chips. The inductor itself is assembled from 4 vacuum tubes with a parallel connection. Such an inductor can be connected to a regular outlet.
There is another option for assembling an inductor with your own hands from an electromagnetic core and two layers of winding. The first layer is 10 turns of copper wire with a thickness of 4 mm, and the second is one turn, the material for which is a metal plate with a cross-section of 15 * 5 millimeters. The electromagnetic core is U-shaped and consists of a set of steel plates. The first winding is made around the plates, which is placed in an insulated housing; the secondary winding connects the core and metal bars, between which there should be a distance equal to the dimensions of the crucible. This entire structure is placed in the furnace body.
So, we get a furnace in which the inductor is located. Wires go from the inductor to the socket. A crucible is placed in this furnace in such a way as to enclose the bars. If it is placed correctly, a buzzing sound will be heard, indicating that tension has appeared and melting has begun. If there is no sound, then use the handle to move the crucible until the circuit is completely closed.

Assembling a cast iron crucible
A metal casing is taken and a glass made of cast iron is placed in it. A mixture of sand and clay is poured between them. A handle is attached to the side. After one or two heatings, the mixture will melt and harden. The crucible is ready. Chips are poured into it and placed in the inductor.

Making a crucible from clay
You can make a crucible from fireclay clay. This is an inexpensive option and also highly resistant to high temperatures. This clay is used for laying stoves and can be purchased at any hardware store. Fireclay clay can withstand temperatures up to 1600 degrees Celsius.
So, you will need fireclay clay (sold in bags in hardware stores), liquid glass (sold there) and ground fireclay. It can be bought or made from fireclay bricks.
In order to make a mixture from which a crucible will be fashioned in the future, take 7 parts of clay, 3 parts of fireclay and 10 tablespoons of liquid glass per liter of dry mixture. Fireclay and clay are mixed until smooth. After this, water is slowly added. In order not to spoil the workpiece, you can pour out part of the mixture, and if there is a large amount of water, add dry powder. You need to knead until the clay stops sticking to your hands.
Only after the clay of the desired consistency has been mixed can glass be added. When adding glass, you need to thoroughly knead everything until the clay stops cracking. It is best to add glass to a lump of clay and roll it into a roll, then fold it several times and repeat the procedure until it stops cracking. The material for the crucible is ready. Until it is used, it must be stored in several layers of cellophane.
There is clay, now to make a crucible you need to take a mold, the easiest way is to use a plaster mold. How to make such a form can be found on any website on plaster modeling. So, directly making the crucible. Before you start sculpting, you need to knock all the air out of the clay; to do this, you can lay a newspaper on the floor and forcefully throw a lump on it several times, ten times will be enough. Now take a lump of clay and carefully press it into the bottom of the mold, after which the walls of the product are formed in small lumps. Their thickness can be controlled along the edge of the mold. It is very important to carefully press the clay into the mold so that no air cushions form there. After the crucible is sculpted, you need to make the inner surface smooth. To do this, just moisten the clay with water.
After this comes the moment of drying. The mold with clay is placed in a cardboard box and covered with a lid. After seven hours, all the water from the clay will evaporate and the shape of the future crucible will “shrink” a little, so getting it out of the mold is not particularly difficult. After this, the crucible continues to dry in the same box; as it dries, all defects will be eliminated by themselves and the pot will acquire a gray color. Sometimes small cracks may appear. They can be covered with wet clay. Next, the pots are fired at a temperature of 800 degrees in a muffle furnace. After firing, the crucible is ready for use.

Graphite crucible
Graphite is a material that has many unique properties. Positive qualities of graphite:
- resistance to exposure to molten metals;
- increase in strength with increasing temperature;
- high heat resistance and thermal conductivity;
- low specific gravity.
To make a crucible from this material you will need:
- graphite powder;
- solid graphite;
- felt;
- graphite tube;
- fireclay mortar;
- magnesite.
Some of these materials can be used as independent units. For example, a graphite tube is essentially already a crucible; you just need to make a bottom in it.
The principle of manufacturing from all materials is the same. Let's look at the example of mortar. Two forms are made. You can roll it out of thick paper to make it easier to remove later. External form has a hollow cylinder configuration, and the inner one is just a cylinder. The small cylinder is inserted into the wider one. The mixture will be poured between them. The mold is placed in a plastic cup and mortar powder is poured into it. You need to fall asleep with a slide, as it will sit down when you need to compact it. 15 cubes of liquid glass are poured into this powder using a syringe. Everything is mixed and the consistency of shortcrust pastry is obtained. Stuff into the mold in small portions.
The result is something like a glass turned upside down. To prevent the form from sticking to the table, it is best to do the entire procedure on cellophane. Then the mold is turned upside down and the inner cylinder is removed. It is also best to initially glue it with cellophane or tape. Then, when removing, the shape of the crucible will not be damaged.
After the crucible has dried, it must be placed in the inductor and heated. This must be done at low temperatures, since all the water should evaporate, despite the fact that outwardly it seems as if it is not there at all. If the crucible is not preheated and you immediately start melting in it, it will most likely burst. After warming up, when you tap the crucible, it will make a ringing sound. This indicates that the crucible is well made.
By following the instructions presented, you can quite easily acquire a homemade melting furnace that will last no less than a purchased one. The main thing is to take your time, be careful in your work and not violate manufacturing technologies.