For the manufacture of forged products, two methods are used - cold and hot processing. The first method is characterized by low labor intensity, but requires the presence of a special tool. In most cases, it is possible to make a machine for cold forging with your own hands, guided by standard drawings.

Principles of cold forging of metals

To produce metal forged products, it is necessary to ensure a process of controlled deformation. In this case, the structure of the material, its technical and operational properties should be taken into account.

The principle of cold forging is based on the influence of external factors on crystal lattice material. It consists of grains of irregular shape. As a result of the distortion of the structure, which is performed by a cold forging machine, the workpiece is compacted and reconfigured. Since one of the conditions is to preserve the properties of the part, it is necessary to select drawings for the production of machines.

Features of cold forging of metal, requirements for devices for this:

• It is possible to process only low-carbon steels that have high degree plasticity;
• rods of various sections are used as blanks;
• preliminary calculation of the dimensions of the final products. During their production, constant monitoring of geometric parameters is necessary;
• using various machines to create the desired configuration.

Currently, a number of special tools are used for the artistic processing of metals using cold forging. Some of them you can do yourself. But for this it is necessary to first study the drawings and specifics of production.

Forged products can perform several functions simultaneously - aesthetic and operational. This applies to barrier structures various configurations, for example, a wave.

Snail for cold forging

The most common and in demand are homemade cold forging machines of the snail type. With their help, spiral-shaped blanks are formed. The design of the equipment allows you to make it yourself.

The drawing of a “snail” machine can be adapted for the production of a specific type of artistic forging product. To do this you need to know the following parameters:

• minimum and maximum radius of curvature of the workpiece;
• geometric parameters and shape of the source material;
• planned performance.

For mass production, it is necessary to make a forging machine with an electric drive. If you plan to work at home, manual models are suitable.

As a basis for designing the snail, it is necessary to use a steel sheet with a thickness of at least 3 mm. This will allow you to bend rods of large cross-section.

To form different angles you need a manual bender - one of the most required devices for cold forging of metal. It consists of a steel plate on which there are two support shafts and a moving stop.

The workpiece is placed between the support shafts and the wedge. The latter has a displacement mechanism towards the stops. As a result of this action, bad things happen. steel bar processing. In this way, forged products of various shapes can be produced.

Features of the use of bending necessary for the correct preparation of its drawing:

• preliminary calculation of the deformation angle;
• an additional bending part can be provided in the design. To do this, install another rotating shaft;
• mounting unit for fastening to the table.

To produce bending, it is necessary to use tool steel. This is due to heavy loads during operation. Additionally, you can assemble elements of the “wave” type on it, but for this you need to modernize the original drawing.

Minimum and maximum bending radius for thin. forging must be calculated based on the geometric parameters of the workpiece.

Twister for cold forging

Modern artistic forging It’s hard to imagine without screw-shaped elements. For the production of such thin. The twister is intended for details - homemade machine for cold forging.

The peculiarity of this tool is the unwinding of the twig along its axis. Structurally, the drawing of the machine consists of two parts - fixing and movable. The part is attached between them and its information is carried out using a rotary knob.

Performance qualities of the device:

• calculation of the pressure lever to minimize efforts to produce blanks;
• possibility of changing the distance between the fixing elements of the tool. This will make it possible to produce parts of various lengths;
• It should be taken into account that the formation of the spiral occurs from the fixation side.

Thanks to twister you can do forged elements for window grilles, steel barriers, etc.

This is the main list of cold forging machines. But besides them, various equipment is used, designed to create truly thin. products.

The video shows examples of machines for cold forging of metals at home:

If you need cold forging, do-it-yourself equipment, the assembly videos of which are presented below, there should be no problems with its production. Your main task is to determine the purposes for which you will assemble the equipment in your own workshop, garage or just on the balcony. Many cold forging devices are compact in size but have wide functionality.

Why do many home craftsmen strive to try their hand at cold forging on equipment? This is due to some features characteristic of this method metal processing.

• Multifunctional forging equipment for cold forging you can make it yourself, which allows you to save significantly financially;
• Factory machines for metal are not a cheap pleasure, because homemade equipment becomes an ideal solution for those who want to do artistic forging with their own hands;
• Metal products obtained by cold forging have an attractive appearance, original design, and can reflect your wildest ideas. You just need to implement them correctly;
• The process of doing cold forging with your own hands using specialized equipment is safe and simple when compared with the hot method of metal processing;
• A homemade device for deforming products does not require the use of elevated temperatures, which entails serious danger. Hot forging can only be done in specially equipped rooms, while cold forging can be done at home without any risk to your home.

In fact, the list of advantages that homemade equipment has can be endless. Instead, we will introduce you to concrete examples devices, we will provide drawings and tell you how you can assemble this or that version of the equipment with your own hands.

Types of machines for cold bending of metal

DIY cold forging scheme

Find drawings, video assembly instructions various kinds equipment designed for cold forging, in the realities of our time, is a matter of a couple of minutes. At the same time, when choosing drawings, it is important to understand what kind of result you are counting on.

Each type of cold forging equipment is designed to perform certain operations with metal. Some craftsmen assemble several machines in one, performing a whole list of tasks with its help.

But for beginners, individual metal processing units are quite suitable. And what exactly they will be, you can decide by studying the list of equipment available for making your own.

1. Snail machines. They may have solid or removable elements. With their help, metal rods are twisted into spirals.
2. Universal machines. This equipment allows you to cut, rivet and deform parts. As you understand, the deformation is controlled.
3. Bending machines. With the help of bends you can make an arc bend of metal at the angle you need.
4. Twister machines. They allow you to make bends along the axis of the finished product made of metal, wood, or plastic.
5. Wave machines. From the name it is obvious that waves give the metal its wave-like shape. They are used to bend metal rods.
6. Presses. If you need to apply a matrix print on a metal part, you will need press-type equipment.
7. Machine for forming rings. He special name does not have, but does an excellent job of performing its direct responsibilities as bending equipment for cold forging.

Homemade snail

The snail is the foundation of the equipment for any beginner or professional cold forging artist. Therefore, if you decide to make yourself a machine, it is recommended to start with a snail. Relevant drawings and videos are easy to find. And the instructions for making a snail with your own hands look quite simple, so you may not need drawings. Such a manual device will allow you to start working on cold forging and create your first metal masterpieces.

To assemble the snail you will need the following:

• Metal rods;
• Steel sheets;
• Metal strips;
• Profile steel pipe;
• Pliers;
• Bulgarian;
• Welder.

If you need a machine more than once, then use the drawings, and to assemble the equipment structure, take only high-quality rolled metal. The durability and efficiency of the equipment directly depends on its reliability.

1. To apply the image of a spiral and 3 turns on a sheet of metal, take plain paper. The rod is placed in the thread, and its diameter should be 10 mm.
2. Cut a couple of plates from a sheet of steel. The size of the first will be 100 by 100 millimeters, and the second will be 130 by 130 millimeters.
3. Be sure to clean the metal rods and strips with sandpaper so that there are no irregularities, defects, or burrs left on them.
4. Bend the steel strips as required by the drawings or your specific needs. You should end up with three spirals of the same shape, but different in length.
5. Execute welding work, based on the drawings. Please pay attention special attention quality of welding, since the durability of your machine directly depends on this.
6. The pipe is welded into the center of the equipment and completes your cold forging machine called a volute.

Torsion equipment

By using torsion bar machine Spiral-shaped products are created using cold forging. You can assemble it with your own hands, but bending the parts manually is problematic. Therefore, the drawings provide for the use electric motors when designing torsion cold forging machines.

If this aspect of the equipment does not scare you, and you are ready to assemble the unit, at the end you will receive excellent equipment for creating original decorative elements.

To assemble cold forging equipment, the following is required:

• Steel beam;
• Sheet of steel;
• Clamps, clamps and vices;
• Electric motor with chain and gearbox;
• Welding machine;
• Corner grinder or just Bulgarian.

The process of assembling a torsion bar machine itself will not require advanced knowledge from you, but certain skills will come in handy.

1. The steel beam acts as the base of your torsion bar equipment.
2. A steel sheet is welded onto one side of the beam by welding. A vice is mounted on it with bolts and nuts.
3. To avoid possible metal slippage in the future, it is recommended to secure metal plates at the bottom and top of the vice.
4. Rollers are mounted on the other side of the beam. You will install the working surface of the equipment on them.
5. At the opposite end there are other disks with moving components. Make sure that the structure is level on both sides.
6. Install the steel handle, secure the gearbox, electric motor and chain.
7. Be sure to provide a protective cover for your design, which will prevent unwanted injuries.

Assembling units for cold forging with your own hands is a task that anyone can do. The main thing here is to decide on the functions that the machine should perform and select the appropriate drawings of the device for its subsequent assembly with your own hands. We advise you to start with the simplest models, and as you gain experience, move on to complex, multifunctional cold-forging units.

The private sector of any city is characterized by a variety of elegant metal products. This is a metal patterned gate, beautiful benches, unusual railings and others decorative ornaments. Forged products add some aesthetics appearance plot and house. Many people believe that using forged metal fixtures is very expensive. But this is not always the case.

Such products are made using the cold forging method. If you buy them in a store, then, of course, you can shell out a considerable amount. That's why experienced craftsmen make a cold forging machine with your own hands. Moreover, if a person likes to do something on his own, then this device will be useful on the farm.

And also, by doing artistic forging, you can make good money. After all, production waste and initial setup costs are small. Therefore, the business of a blacksmith engaged in cold forging can quickly go uphill. Forging may be carried out in a garage or shed. Accordingly, renting premises is not required.

Cold forging concept

The cold forging procedure differs from the hot forging process in the simplicity and safety of the process. Metal is not exposed high temperature. Compared to stamping, this process involves almost complete elimination of metal flow. If we consider cold forging, from the point of view of the forging process itself, then this is the process of riveting elements using impact force.

As a result, the strength of the outer layer increases, and the inner part imparts overall toughness and fracture strength. Of course, the forging procedure itself is very lengthy. Therefore, it is worth talking in more detail about a certain branch of cold forging called artistic forging.

It is also essentially cold forging, and henceforth the term “cold forging” will be used. It consists of various bending of metal sources. The structure of the metal base does not change. Physical and mechanical properties also do not change.

Cold forging involves the formation of a variety of twisted elements and bends. Such patterned elements are made on a specific installation. Moreover, the drive of these installations is divided into manual and electric. For large volumes of work, it is preferable to use machines with an electric drive to increase the speed of execution.

Manual installations can be used to produce the following decorative items:

1. Designs for windows.
2. Components for making railings.
3. Chairs, benches.
4. Furniture legs.
5. Decorative items for gates and wickets.
6. Parts for fireplaces.

As for the starting material used for forging, they are used different types: aluminum, copper. You can also use alloys - duralumin, steel, brass, magnesium alloy, nickel alloy.

Advantages of the method

When compared with other methods of producing metal products, cold forging has a number of advantages. These include:

• Heating of the metal is not necessary, which simplifies the manufacturing process due to the absence of a furnace and maintaining a certain temperature.
• Process safety.
• Ease of production of cold forging installations.
• The ability to correct a manufactured product due to its mechanical properties.
• The ability to manufacture equipment for the production of identical products with standard steps.
• Saving time and money when performing work.

The presence of these advantages makes cold forging technology widespread.

Equipment types

There are many types of cold forging machines. The following categories are established:

1. Gnutik - helps to obtain metal arcs that bend at a precise angle.
2. Snail - a device that allows you to form a spiral from rods.
3. Twister – allows you to obtain a more complex spiral formation along the axis.
4. The ring is a bending mechanism for making ring and oval shapes.
5. Wave - the installation is intended for bending rods into a wave.
6. Press - allows you to carry out the process of flattening an object.
7. The hammer and the anvil are tools that help correct mistakes.

Making a cold forging machine for each of the listed categories with your own hands is quite easy. All you need is some tools and metal material. Especially cash almost no need.

Manufacturing a mechanism for cold forging

A universal cold forging machine is almost impossible to make with your own hands. It is necessary to make a separate form of mechanism for releasing objects.

When manufacturing the installation, it is necessary to select the following materials:

• metal sheet (preferred thickness 4-5 mm);
• reinforcing bars, profile pipes;
• bed for stability of the device for cold forging;
• electric motor and gearbox in the case of a machine with a drive.

Of course, making fixtures cannot be done without tools. It is advisable to have an angle grinder or a metal file, a welding machine, an emery stone or paper, a vice and pliers, as well as a pencil, tape measure and paper.

The easiest way for a novice craftsman is to make a homemade machine for cold forging the shape of a snail. Thanks to her, they are produced various shapes metal rods for gates and fences. The torsion bar type of installation is also popular. Other forms of machines can be made after gaining experience with simple setups.

Let us examine in detail the production of the “snail”. This device helps to obtain a variety of configurations of spirals, curls, and rings. Simple design this equipment contributes comfortable work and easy access to the workpiece. The process can be carried out if:

1. Metal rods.
2. Steel leaves and stripes.
3. Profile pipes.
4. Welding machine.
5. Angle grinder and pliers.

To make homemade machines used during cold forging, it is advisable to draw a diagram or sketch of the future device. Initially, graph paper is selected for drawing the drawing.

The following stages of work:

• An image of a spiral with three turns is applied to a sheet of paper. The dimensions must correspond to the diameter of the reinforced rod with the condition that it fits into the thread. It is best to use the 10mm size. And also the lines should be drawn based on the thickness of the steel, and the distance inside the spiral should be 12-13 mm.
• Next, you need to use a steel grinder to make a circle of the required diameter. If you want to use removable circles, you should take a non-thin source material (4-5 mm thick) for easier replacement.
• Making a durable frame that is stable on the floor surface. You can, in general, concrete the legs for a more durable structure. An important condition is that the frame circumference should be more sizes working circle.
• Welded to the frame metal rod, onto which the bearing device is mounted. Manual control involves welding the circle to the frame. In this situation, metal bending occurs much easier than during the rotation process.
• We fix the snail on the circle. The snail is divided into three parts. The tail part has a height of 1 cm based on the thickness of the rods. 1 cm is added to the next part of the spiral. This means that the second turn will be 2 cm, and the third - 3 cm. Upon receipt more turns, the details of the spiral should be increased.
• If it is necessary to make replacement circles, then the replacement parts are welded to the circle according to the sketch.
• If you have a replacement volute, you need to measure the position of each type and weld the studs to each element. In this case, a gap is made in the circle for a certain part.
• To get a forged product, you need to start with the central coil. It is necessary to firmly secure the rod using a vice or other tool.
• At the end you need to make a lever out of two profile pipes(diameter 15-20 mm). They are welded with jumpers, the length of which is the distance from the center of the bearing to the top point of the circle plus 5 cm. Next, it is welded to the bearing part. A rod with a length corresponding to the length of the tallest part of the snail is welded to the lower part of the lever, which is the cut round part. A bending barrel is welded perpendicular to the area of ​​the circle.

Thus, the homemade machine is ready. You can start production necessary elements. To do this, the rod is fixed, and then the barrel rests on it, and the bending process begins.

Video: DIY cold forging machine.

Torsion bar machine

Another popular device, such as a do-it-yourself cold forging machine, is a torsion bar. It is used for forging snake-shaped spirals. To make the installation you will need:

1. Sheet of steel.
2. I-beam.
3. Vise.
4. Parts for fastening.
5. Angle grinder.
6. Welding.
7. Gearbox and electric motor.

To make this installation yourself, you need to go through certain steps:

• First you need a beam, a sheet of steel is welded to one part of it.
• Next, a vice is welded to the steel, which then needs to be secured with bolts and nuts.
• Plates are attached to the vice to reduce the risk of the object jumping out when tensioned.
• On the other part of the beam, rollers are installed to secure the platform. Moreover, the device with rollers must be at the same height as the design of the vice.
• A vice with movable parts is placed on the completed installation.
• A steel handle is attached to perform rotation. As a result, the workpiece will bend.
• Next, the electric motor is connected, and the entire system is covered with a steel casing.

Thus, the structure made is a machine with a movable and fixed block. This method of manufacturing a machine is quite simple, but requires some effort in operation.

In front of many people interested metal objects decor, the question arises - how to make a cold forging machine with your own hands. Having studied this issue in detail, you can, without experience and a workshop, produce various metal products for landscape purposes.

The machine is quite simple to make using tools and materials that almost everyone has. Moreover, your equipment can be adapted to any type of product.

Forged hardware They add color to any interior and look very aesthetically pleasing. But not every owner of a house or dacha wants to have standard solutions that the market offers. In addition, forged decorative elements are very expensive.

Hot forging requires serious skills, equipment and work space. The ideal solution To realize your design fantasies, use cold forging devices. Not everyone can afford to buy such machines, but making the device yourself is not so difficult.

1 Advantages of cold forging

When processing metal using this method, heating is not required. Consequently, no furnaces, no temperature control, no skills in working with hot metal, no special work areas, etc. are required. In addition, there is no danger of serious burns.

Cold forging devices involve bending and pressing of metal. Machines for performing these processes can be either electric (you will need an electric motor and gearbox) or manual. They are easy to make with your own hands and easy to maintain. The design of the units themselves is absolutely elementary, but it is worth knowing that the process of hand forging itself requires considerable effort from the worker.

Unlike decorative elements, obtained as a result of processing hot metal, the product of cold forging, if necessary, can always be remade. It unbends as easily as it bends.

The method of creating decorative elements from metal without heating is very convenient when you need to make many of the same ones. In this case, it is made homemade device for a specific drawing with specific dimensions and template actions are performed.

A bending machine significantly saves time, effort and financial costs on equipment of the premises and the metal processing work itself.

1.1 Purpose of the device

The cold forging device allows you to perform absolutely all work, performed by a blacksmith who processes hot metal. Hand tools will cope perfectly with the production of such decorative elements as:

• window grilles;
• constructive for handrails of stairs, benches, chairs;
• legs, frames and other elements of home furniture;
• design of various fences, gates, wickets;
• flower stands, fireplace grates, shelves and much more.

In the cold forging process, exclusively soft metals are used, such as aluminum, duralumin, steel, copper, brass, magnesium and nickel alloys.

1.2 Types of units

To create a decorative forged metal interior, you will need several types of parts. Among them are spiral rods, arcs, spirals, and various sheet metal parts.

It is almost impossible to make a universal machine for cold forging with your own hands, so to create each element you will have to make a separate device. Such devices include the following units:

1. Gnutik. Allows you to produce metal arcs curved at a certain angle.
2. Snail. This device is designed for bending reinforcing and profile bars into a spiral.
3. Twister. A tool for bending a rod into a spiral along its axis.
4. Wave. A device designed for bending a reinforcing or profile rod into a wave element.
5. Ring. For making rings and ovals.
6. Press. A device designed for flattening metal products.
7. Hammer and anvil. Very helpful universal tools, allowing you to correct shortcomings.

All units designed to perform the above tasks can be either manual or electric.

To operate the latter, you will need an electric motor and gearbox. Electrical machines, having an engine and a gearbox, they perform work much faster and alleviate the lot of the worker himself.

2 How to make a cold forging machine at home?

Making a machine of any of the above types with your own hands at home is very simple. You don’t need any fancy tools or expensive mechanisms and materials for this. Everything you need for such a device can be found in almost any garage.

2.1 Materials and tools

Regardless of what kind of device you plan to make, you will need the following materials:

• sheet metal 4-5 mm thick;
• reinforcing bars, profile bars or profile pipe;
• stable bed;
• If we are going to make an electric bending machine rather than a manual one, we will need a low-speed motor and gearbox.

To organize the process of manufacturing a unit for cold forging, you need to stock up on the following tools:

• "grinder" for cutting metal elements(if this is not available, use a metal file);
• welding machine;
• emery stone and sandpaper;
• vices and pliers;
• paper, pencil, marker;
• tape measure or centimeter.

2.2 Manual machine “snail”

Spiral-shaped elements are most often used to create a “forged” interior. So let's start looking at production process from the snail machine.

A homemade electric unit will require, in addition to the usual set of parts, the use of a motor and gearbox. The gearbox is used to reduce engine speed. But we'll talk about this later. In the meantime, let's look step by step at how to make a hand-held device.

Note also that one machine can make spirals different diameters, but for this you will need a removable snail. This can be achieved in two ways: solid metal removable circles with a welded scroll, or one circle with removable parts of the spiral.

The homemade apparatus for cold forging is ready. You can lay the rod, fix it, rest against it with a bending barrel and walk around until you get the desired product.

2.3 DIY cold forging machine 3 in 1 (video)

2.4 Electrical analogue

The only difference is that the engine must rotate the working circle through a reduction gearbox. The bending barrel is welded directly to the circle without affecting the gearbox. Otherwise, the manufacturing principle of the unit is absolutely identical, and the gearbox and electric motor only complement it.

Comments:

To add beauty and sophistication to metal gates or fences country dachas or private houses, spiral elements are increasingly being used. In order not to buy such elements in stores, manufacturers of fences and gates often bend them themselves. To make spiral-shaped steel parts yourself, you need a special device called a snail. With the help of such a device, metal rods and strips are bent different sections. If the workpiece has a square cross-section with a side of up to 12 mm, then such workpieces are bent with your own hands at normal temperature (so-called cold forging).

Figure 1. DIY drawing of a snail.

Considering that such a machine is needed by people who usually work with metal, they can make it with my own hands. In order not to waste time and money reinventing the wheel, drawings of a snail for cold forging will help them. It is good to use low-carbon metals for the manufacture of spirals due to their good ductility characteristics.

General structure of the machine

Figure 2. Drawing of the base of the cochlea.

A cold forging snail is a metalworking device that contains a device that fixes the workpiece. A shaft with a spiral element is fixed to a thick metal disk or plate.

The end of a rod or strip is inserted into the locking device, then a rotating shaft winds it onto a spiral element.

The bending occurs from the action of the pressure roller, which presses the workpiece against the spiral element. Depending on the design of the desired product and its size, for each type of figured part, separate snails or snails are made with the ability to change their curvature.

There are several options for drawings for making a cold forging machine. Based on the type of shaft drive in machines, they can be manual or electric. First, let's look at a drawing of a machine for cold forging of a manual drive.

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Drawings of a manual machine

Figure 3. Drawing of the base of the cochlea.

The machine, according to this drawing (Fig. 1), is mounted on a base, which is a plate rectangular shape dimensions 220x190 cm.

This 5mm thick plate has two holes. One of them is round, with a diameter of 14 mm, for the shaft axis, and the second is oval, with a width from 6 mm closer to the shaft axis to 7 mm further from the axis (Fig. 2). This base is welded to two legs, which have a hole for attaching them (Fig. 3).

The shaft axis has a tapered end. It is firmly attached to the base with two M14 nuts.

The drive axle is freely put on the axle, which has a head with two mutually perpendicular through threaded channels (Fig. 4).

Handles are screwed into these channels.

Parallel guide rails (2 pieces) are welded to the lower surface of the base along an oblong hole.

Figure 4. Drawing of the cochlea axis.

The spiral-shaped element (the snail itself) is prefabricated. It consists of 4 elements, hingedly connected to each other by pins threaded through the eyes (Fig. 5).

Each cochlea segment connecting pin has a knurled head.

The arcuate lugs have holes for the connecting pin. They are welded to the ends of the segments. The amount of bending of the cochlea is regulated by special adjusting screws, which are screwed into the connecting end of each of the three segments so that they rest against the end of the previous segment.

Each adjustment screw has a slot on one end surface for a flat-head screwdriver.

The central segment of the volute is an eccentric with a hole for the drive axis, the first part of the spiral element and a fixing cutout. The fixing cutout is an eccentric semicircular recess in the first part of the segment with a radius of 7 mm, the center of which is located at a distance of 8 mm from the center of the part. The thickness of the central segment, like the other segments, is 25 mm.

Figure 5. Drawing of a cochlear segment.

Eccentric with grooved bottom, in the transverse channel of the head of which a lamb is inserted, is placed inside the guide. The latter is aligned coaxially with the semicircular cutout of the drive axle, and then welded.

A slider is inserted into the longitudinal hole of the base, which is pressed from below to the base. The slider fits freely between the guide rails using the flange cutouts.

IN top part The slider is screwed into the roller axis, which has a hex head.

The roller itself is loosely attached to the roller axis.

In this way, the roller can take a position along the oblong hole of the base and is fixed in any such position by screwing the roller axis onto the slide.

Working with this device is quite simple. To begin, insert the end of the rod or strip into the recess of the drive axle. By turning the eccentric using the thumb, the workpiece is clamped between its lower end and the walls of the recess. To do this, the roller is brought to the workpiece, the roller axis is screwed in wrench at 12 on the slider, clamping it. The workpiece is placed between the eccentric of the central segment of the volute and the roller.

Next, turn the drive axis clockwise, winding the workpiece over the central segment. When the workpiece is wound to the end of the central segment, a second segment is attached to it using a connecting pin. The roller moves to a new position.

And so on, it is bent until the workpiece is given the desired shape. To remove the resulting product from the machine, the eccentric is turned with a thumb and the end of the workpiece is released. Having lifted the drive axis with the eccentric and the entire volute, the latter are removed from the manufactured spiral.