How to cut external threads

How to cut threads - types and purpose of the tool

Due to their high reliability and simplicity, threaded connections are widely used in various building structures, machines and mechanisms. Since the basic geometric parameters of threads are generally accepted, it is enough to have a small set of standard tools to create new connections and repair worn units.

1. Internal thread
2. External thread

Internal thread

The internal thread is cut into the hole using taps (1). They are metal rods with hardened teeth. Manufactured from tool or high-speed steel.

Types of taps

Taps are distinguished by purpose. They can be used for cutting metric, inch, tapered, pipe, and trapezoidal threads. According to the relevant technical specifications, as well as GOST 3266-81, the table shows the limits of applicability of this tool.

Thread name	Nominal diameters
Metric	1 - 52 mm
Inch	1/4” - 2” (inches)
Conical	1/16” — 2”
Pipe	1/16” — 6”
Trapezoidal	5.6 - 90 mm

Taps for cutting metric and inch threads are manufactured in sets. The set can consist of either two, finishing and roughing, or three - roughing, medium and finishing taps. The roughing tap is designed to remove the bulk of the chips. Finishing is used for the final, precise shaping of the thread profile and calibration.

To identify the tap in the kit, its tail part is marked with one, two or three ring marks. It is also possible to designate using a number: I – rough, II – medium, III – finishing.

Nut taps are designed to cut threads in one pass. They are single-set, that is, sold individually.

To rotate the taps, use knobs (2). They can be non-adjustable with square holes for a fixed size shank, or adjustable. In addition, there are wrenches with a ratchet mechanism, providing ease of work in hard-to-reach places.

External thread

The external thread is manually cut into dies (5) and plugs (4). The die is a round nut made of high-speed or high-hardness tool steel. In order to remove chips, special holes are provided in it. The dies are either solid or split.

Split dies have a slot up to 1.5 mm in size. Thanks to this, they allow you to adjust the diameter of the cut thread within 0.1-0.3 mm. Their disadvantage is less accuracy, so using such a tool in critical connections is not recommended. The diameters of the dies are presented in the table.

Thread name	Nominal diameters
Metric	1 - 76 mm
Inch	1/4” - 2” (inches)
Pipe	1/8” — 2”

The rotation of the dies is carried out using die holders (3) and ratchets. These devices typically allow multiple cutting tool sizes, such as M16 - M20, 1/2" - 1". Ratchets are used for cutting pipe threads with dies in hard-to-reach places, for example, near a wall.

The dies are designed for cutting external pipe threads with a diameter of 1/2" - 3". Thanks to their design, they are securely fixed to the pipe, which ensures ease of operation, as well as high quality threaded connections. Clupps are usually equipped with replaceable cutters or heads. This significantly increases their service life. Depending on the design, both removable handles and ratchet holders can be used to rotate hand clamps.  

Source: https://tehnouzel.ru/ruchnoy-instrument/chem-narezat-rezbu-vidy-i-naznachenie-instrumenta.html

How to cut threads on pipes

› To the master

articles Best products from AliExpress HERE ⬇

To assemble modern pipelines, pipes made of plastic or metal can be used, and a welding machine is used to connect plastic pipes. As for metal products, their assembly involves the presence of threaded fittings: this ensures maximum connection strength. To implement this method, threads will need to be cut on the pipes themselves.

What tool do you need?

Threading pipes will require the following equipment:

1. Tape measure, pencil, caliper . To assemble the pipeline, it is necessary to develop a diagram in advance. First, a pipe with the specified length is taken: markings are made with a tape measure and a pencil. Using a caliper, the diameter is measured and suitable devices are selected. When marking, it is important to maintain considerable precision and accuracy, since any deviation from the specified size leads to a violation of the correctness of the entire structure. As a result, in such cases it is often necessary to redo the entire pipeline.
2. Bulgarian . Using this tool, pipes are cut according to the marked marks. A simple hacksaw for metal can perform the same functions.
3. Vise . During operation, the pipe must be securely fixed in a strictly horizontal position.
4. Machine oil or other lubricant . To facilitate manual thread cutting, it is practiced to lubricate the tool and the area being processed with a special substance.
5. Thread cutting tools . Pipe threads can be cut with a die, a die or a tap. Which tool to use depends on the type of thread being cut and the preferences of the performer. For different jobs, different pipe threading kits are used, depending on the situation. The external thread is cut with a die, which is held by a die or die holder. To apply internal threads you will need taps.

Do-it-yourself thread cutting

How to cut pipe threads yourself?

Self-threading begins with a number of preparatory measures:

1. Cutting a piece of pipe to size . When replacing a damaged section of a pipeline, the first step is to carefully cut out this section in a direction strictly perpendicular to the wall. If this condition is not met.
2. Cleaning the thread area . From the place where the pipe thread will be cut, all paint and corrosion must be completely removed: if this is not done, the work can be clearly difficult.
3. Chamfering . To make the work easier, you need to remove the chamfer from the ends of the pipe.

Thread cutting using a die

The die is used for cutting external threads, which requires the following operations:

• Select a die with the required diameter. To make the selection correctly, you must definitely check it with a caliper.
• Lubricating the internal cavity of the clamp and the prepared area on the pipe using machine oil.

Source: https://moy-instrument.ru/masteru/chem-mozhno-narezat-rezbu-na-trubah.html

Thread cutting tools. Types and work. Application

A threaded connection is one of the most popular ways of fastening various parts and elements. It is not always possible to purchase various fasteners that already have threads applied, so you need to cut them yourself. For this purpose, specialized thread cutting tools are used. With their help, it is also possible to renew previously worn or otherwise damaged threads.

There are 3 types of tools used for thread cutting:

The cutting tool differs not only in diameter, but also in the type of thread created. It can be metric or inch. Metric is used on the vast majority of fasteners. It is used in mechanical engineering, household equipment and other areas. Inch threads are used exclusively on plumbing elements. In some countries, metric threads are not used at all, and all fasteners are made using inch threads.

Another important difference between such a tool is the direction of the thread being created. It can be left or right. You cannot use one tool to cut threads in both directions if it is not universal.

Tap

A tap is a cylindrical tool that is designed for cutting internal threads in pipes and nuts. Its surface has protruding ribs, which, when screwed into hollow metal elements of suitable diameter, create helical grooves, cutting out chips. As a result of screwing in, the tap creates a thread.

This device is a small metal rod made of high-quality hard steel, at one end of which there is a cutting part, and at the other a shank for connecting a wrench. There is a recess along the surface of the tap, through which the removal of cut chips is ensured. The most convenient for use are tools that have 3-5 grooves for chip removal.

They clog much less and provide a clean surface without visible deformation. After cutting the thread using a tap, the bolt or stud is screwed effortlessly over the entire surface.

Using a tap, you can cut a thread or calibrate it if it is damaged.

This tool comes in three varieties:

Hand taps are usually offered in a set of 2-3 tools of the same diameter. The former provides rough thread cutting, while the latter creates a high-quality, smooth profile that allows bolts or studs to turn easily. The order of use of the taps that come in the set is indicated by numbers on their body.

Machine tools are designed for cutting threads on machines. They have a different groove profile for faster chip removal. In this case, the shape of the shank is adjusted to fit into the chuck on the machine.

Nuts are used specifically for nuts. They are easy to recognize because they are the shortest. Since this tool is designed for cutting threads only in nuts, which are usually small in width, it is made very short. In this regard, its length allows you to make a maximum of 12 turns. Nut taps can also be roughed or finished. The roughing only creates the initial thread for screwing in the intake part of a longer tool.

To properly secure a hand- or nut-type tap, a special wrench is used, which is mounted on the shank. The rake angle of a tap determines its application and the metal it can work with. The angle with an inclination of 5 to 10 degrees makes the tool convenient for processing steel. A slope of 0 to 5 degrees is intended for cast iron. Taps with sharpening from 10 to 25 degrees are used for non-ferrous metals and their alloys.

Die

The die (die) is used to create screw threads on bolts and studs. It is a round washer with a central hole, which has several protruding ribs with a sharp edge. The die cuts and calibrates external threads in one pass.

It is usually used for cutting threads on rods with a diameter of up to 52 mm. The standard thickness of the dies is from 8 to 10 turns. The angle of the cut protrusions on the die may vary. A tool with an angle of 40-60 degrees is used for through passage.

In the event that it is necessary to cut the thread close to the stop, a die with an angle of 90 degrees is used.

In order to obtain a high-quality cut thread, it is necessary that the diameter of the rod that will be processed be 0.3-0.4 mm larger than the internal size of the die. Also, when using this tool, it is worth considering that chamfering on the edge is required. In order to hold the die, special cranks are used.

The die can be solid or cut. The solid one has protruding teeth for cutting into the metal over the entire surface. Using such a tool requires serious effort. Much more popular are cut dies, which have separated working parts, which reduces the contact area. This makes it easier to remove chips and reduces friction.

The die can be used for cutting threads on the right or left side. There is also a universal tool that works equally well in both directions. It is designated by the marking LN .

Klupp

Klupp is practically the same die, but significantly larger. It is a system of cutters installed directly into the holder, which also serves as a guide. Typically, this thread cutting tool is used for cutting external threads on pipes as well as thick metal rods. Clamps offered on the market usually have not only a metric stroke, but also an inch stroke. Clamps are usually used by plumbers to prepare pipes.

The dies are sold as a set, which includes one holder and several dies. The attachments can be easily changed. There are also electric clamps that are fixed on the pipe and they themselves cut the thread on it. Thanks to their own gearbox, they are able to create great forces, even with a weak electric motor.

Features of using a thread cutting tool

In order to obtain a high-quality thread with a smooth surface, the workpiece with which the work is being done must be secured in a vice. If this is not possible, for example when re-threading a water pipe that is already installed, it should be held with a pipe wrench.

In order to get a high-quality result, it is also important to choose the correct diameter of the thread cutting tool. If a tap is used, it should be 0.2-0.3 mm larger than the hole into which it is screwed.

If a die or die is used, then, on the contrary, the rod should be larger, by about 0.3-0.4 mm.

It is recommended to prepare lubricant before starting work. This will reduce friction and reduce stress. In addition, the presence of lubricant helps to avoid the formation of burrs and excessive overheating of the part.

When using a die or tap, it is worth making several turns without using a lubricant. This will allow the teeth to cut firmly into the metal at the correct angle. If you immediately try to cut a thread on a slippery surface, misalignment may occur.

As a lubricant, you can change machine oil, grease, diesel fuel and even lard.

When working with aluminum, it is recommended to use kerosene as a lubricant. For very hard steels, the hardness of which is almost equal to the tool used, it is worth using drying oil.

When using thread cutting tools you need to do it correctly

After completing several turns, it is necessary to reverse the process. This will effectively remove the resulting chips and improve the surface of the formed protrusions. In this case, the previously applied lubricant should be periodically renewed. If there is no machine oil, grease or lard, as a last resort, you can use very soapy water. It is significantly inferior in viscosity, but is quite capable of improving the passage of the tool.

If you are cutting an internal thread, you should pay attention to the fact that first you take a tap that has an incomplete thread. It can be recognized by its tapered tip and the marking “1”. It makes shallow cuts, which can hardly be called full-fledged carving. After this, a more even tap is used, on which a marking in the form of the number “2” is applied. As it passes, it deepens the existing groove and makes it suitable for screwing in bolts and screws.

Some sets have a tool marked “3”. It allows you to prepare a threaded connection with even better quality, bringing it to perfection. When changing taps, it is worth considering that subsequent addition of lubricant is a prerequisite. Its absence can lead to early wear of the tool.

After threading tools are removed from the treated surface, they should be wiped with a dry cloth. This is especially important if soapy water was used as a lubricant. The same goes for lard oil. These substances are quite sticky, so they promote the adhesion of dust and dirt, which will subsequently lead to clogging of the thread and its sticking when screwed in.

Related topics:

Source: https://tehpribory.ru/glavnaia/instrumenty/instrumenty-dlia-narezki-rezby.html

What can you use to cut threads? What tool is used to cut threads?

A tap is a device that allows cutting internal threads. In its design, it is similar to a screw made of high-strength steel, on which three or four straight longitudinal recesses are made, forming metal-cutting edges when the screw threads intersect. The working part and the shank of this tool are distinguished. The working element of the tool consists of: cutting and guiding parts.

The metal-cutting side resembles a cone and is used for cutting. The guide side sends the tool into the working hole, in which the thread is cut and calibrated.

At the end of the tail there is a connecting square, which is necessary for fixing the tool in a hand tool. The size of the connecting square for a manual drive depends on the size of the tap.

The grooves on the working side of the tool have longitudinal recesses. The thread turns are separated by grooves into cutting feathers, the leading edges of which are used for cutting. Also, the recesses are needed to remove chips that appear during work. Three grooves are usually produced on tools with a diameter of up to 22 mm, four grooves - with a diameter from 22 to 52 mm.

The tap for thread cutting is made from high-speed or carbon steel using technologies approved for the manufacture of metal-cutting tools. They undergo heat treatment, the accuracy of which determines the performance and durability of the tap.

The surface hardness of the taps should be in the range of 63 - 66 HRc. Items made from carbon steel have much less durability than models made from high-speed steel.

To increase the hardness and durability of the cutting edge, the working part of machine taps can be coated with titanium nitride of a characteristic “golden” color.

There are two ways to cut internal threads with hand tools: European and American. In Europe, it is customary to work in two or three passes with different taps. In the USA - one per pass.

In the USA, for example, metric threads are widely used, and similar devices for the metric system offered by American manufacturers are designed to work in one pass.

Threading tools European production offers a wide range of devices only for the metric, but also for the inch system. However, both of them are offered only in the form of two- or three-pass kits.

In Russia, the European approach is adopted, in the Far East - the American one. Accordingly, below the main attention is paid to these devices for cutting threads using the European method. A set of two (rough and finish pattern) is used for working on soft steels, and a set of three (roughing, medium and finishing pattern) is used when working with harder metals.

Inside the set they differ in the number of marks (rims) applied to the shank. As often happens, there are no standards for such designations, and there are domestic and foreign designation systems. In the domestic system, one risk means a rough model, two means a medium model, and three means a finishing model. In foreign sets the finishing is usually without marks.

It should also be borne in mind that marking errors are possible (they occur even among the most famous manufacturers) and the most reliable way to distinguish the taps inside the set is by the length of the lead-in part, which consists of cutting feathers of reduced diameter, with cut off tips. Their diameter gradually increases from the end of the tap to the shank. The draft model has the deepest lead-in side. It usually contains from four to nine turns. The shortest lead-in side is for the finishing model, from one to three turns.

And the average number of turns of cutting feathers on the lead-in part is located in the middle between the above-mentioned items of the same set.

To work in blind holes, taps are required that have a minimum number of feathers on the lead and a blunt end. The tail is usually marked with the value of the thread cut by this tool. On imported items, in addition to the thread size, the diameter of the drill for this size is often indicated.

The shank of all items ends with a connecting square, which is necessary to hold the device in the collar. There is no standardization of square sizes based on thread ratings. For example, a tap for an M10 thread from one manufacturer may have a square of 5.5 mm, from another – 8 mm. Dimensions of squares on tap shanks, mm: 2.1; 2.7; 3.0; 3.4; 4.9; 5.5; 6.2; 7.0; 9.0; 11.0; 12.0; 14.5; 16.0; 18.0; 20.0; 22.0; 24.0; 29.0; 32.0.

Tap sockets

The drivers are used to work with a tap. The shank of this device is inserted and clamped into it. Such hand tools are available both non-adjustable, with a fixed seat size, and adjustable, with a variable seat size.

A flat non-adjustable driver usually has from one to three holes of various sizes to fit the most common square sizes on the tap shanks. Today, such gates are practically not produced. Unregulated wrenches with a ball head are produced abroad. Four square holes of different sizes from the above size range are made in the head at right angles.

Adjustable wrenches contain a screw mechanism in their design that moves the clamping parts that secure the shank of the device. Extension cords may be required when working in hard-to-reach areas. They are usually non-adjustable and are designed for only one size of connecting square.

 End wrenches are used for working in hard-to-reach places. They are equipped with a locking chuck with jaws on which are made to fit a square on the tap shank. They are manufactured with both a fixed chuck and a ratchet chuck. The ratchet must have a three-position direction switch (the middle mode locks the chuck).

When working with such a tool, you must follow simple rules, namely:

1. Use a lubricating fluid that helps minimize force, increase the quality of work and service life of the device;
2. When passing with the first tap, it is necessary, and when passing with subsequent ones, when creating resistance to rotation, for every quarter or third of a turn, back up to remove chips.

Dies and devices for working with them

 To cut external threads, a device called a die is used. It is similar to a round or hex nut made of high speed or carbon steel, hardened to a hardness of 63 - 66 HRc. The first version of such a device requires a special holder; a hex holder can be used with a regular wrench.

However, it is still better to start cutting a thread with a hexagonal die with a die, since it provides better conditions for controlling the die at the moment of entering the thread, allowing you to more accurately align the plane of the die perpendicular to the axis of the workpiece.

Then, when the entry is completed, it is better to use a wrench, since the hex profile works better under heavy loads.

Three to five through longitudinal holes are cut in the die around the central threaded hole, offset at equal distances from the center of the device. The generatrices of these holes and the threads of the dies at their intersections create cutting edges. They also serve to remove chips generated during work.

On both sides of the die, the cutting edges have chamfers to a depth of 1.5 - 2 threads, which are called intake parts. Three or four recesses are made on the side components of the dies (with an angle increment of 120° or 90°) for locking screws that secure the device during operation.

On the front surface of the die there are usually numbers indicating the size of the thread that the die cuts.

Almost all round dies have a recess along the side generatrix with a trapezoidal cross-section to a sufficiently large depth. Once noticeable wear is reached, the die can be cut along this recess and then it can be used as a split die, thereby compensating for its wear. You just need to remember that the rigidity of the cut die is significantly lower and the accuracy of the thread dimensions decreases noticeably.

In the split die, a side slot 0.5-1.5 mm wide is initially provided. It allows you to adjust the diameter of the thread along the cutting edge within small limits (0.1-0.25 mm) and thereby compensate for the wear of the cutting edge or the increased hardness of the material being processed.

Previously, such dies were widely used in industry, but now they are completely out of use. Dies are available with an adjusting conical screw, which occupy an intermediate position between conventional round and split dies.

In such a die, a cut along its wall is made at approximately two-thirds of the height and ends with a threaded conical hole into which a conical screw is screwed, which serves to accurately adjust the diameter of the die along the thread. This adjustment allows you to compensate for both different hardness of the workpiece material and die wear.

At the same time, the rigidity of the die does not drop much and the design with a conical adjusting screw seems to combine the advantages of a solid and split die.

Klupp

A clamp is a tool used to hold a die when cutting threads. The die is similar to a round holder with an internal diameter that is larger than the outer diameter of the round die. This tool has several threaded holes into which hardened locking screws are screwed in to secure the die.

The number of locking screws varies in different designs from one to five. It was mentioned above that three or four holes for locking screws can be made on the side surface of the round die. A trapezoidal notch on the side generatrix of the die can also be used as a stop for the locking screw.

Accordingly, the number of screws actually used varies from one to four, depending on the design of both the die and the die. By using more locking screws, the load on each screw decreases, but the rigidity of the fastening decreases.

Hexagonal dies are clamped along one, two or three surfaces, the rigidity of their fixation is significantly lower.

Two knurled handles are screwed into the die forming parts opposite each other to rotate the die during operation.

There are dies equipped with adapter rings with the same outer diameter, equal to the inner diameter of the die holder, but with different inner diameters for dies of different sizes. The adapter rings have through holes for the clamping screws. The assembly of the die and adapter is inserted into the die, and the locking screws are screwed through the holes in the ring until they stop into the holes made in the die, fixing both the adapter ring and the die.

To work in places with limited access, sometimes it is necessary to make rather complex designs of clamps using a homemade method.

Source: https://www.aist-tools.ru/useful-information/review-articles/chem-mozhno-narezat-rezbu/

Thread cutting tool

The threaded type of connection is the most widely used today. It is used in mechanical engineering and other areas of production, is characterized by high reliability and ease of manufacture. If desired, you can cut the coils using special tools, which are characterized by practicality and versatility in use.

Thread cutting tool

General information about threading

When choosing a tool for cutting threads, you should take into account the characteristics of the threaded surfaces. These include the following points:

1. The cutting of turns is carried out mechanically using special equipment. When metal is removed, grooves and coils are formed that fit perfectly with the surface of the second element.
2. All thread cutting tools and technologies used can be divided into two categories: manual and automated. For a long period, screw-cutting lathes were used.
3. When using hand tools for thread cutting, lubricant must be used. It significantly extends the service life of devices and simplifies the threading process itself.

Thread cutting with different types of dies

It is worth considering that manual versions have an internal surface, which determines the size of the turns and their location. In the case of processing on a screw-cutting lathe, the parameters of the future threaded surface are determined by the feed and speed of movement of the caliper.

When using turning and screw-cutting equipment for thread cutting, you should select the most suitable cutter. Manufacturers produce special versions of cutters for thread cutting, which are characterized by their specific features:

1. During production, a cutting part of a certain shape is created. Due to this, a groove of the required shape is formed.
2. The cutting part is made of tool steel, which is hardened. Due to this, the possibility of rapid wear of the cutting edge is eliminated during operation.
3. The use of the method under consideration makes it possible to process the surfaces of large workpieces.

Shaped cutters

In production shops, a screw-cutting lathe is often used, since there are practically no dies and taps for working with large-diameter workpieces. In addition, when threading, a serious load arises.

Threaded dies for increased productivity

Some thread cutting tools are characterized by high efficiency when used. An example is thread dies, which can be used to produce threads of almost any size. Their advantages include the following:

1. Simple design.
2. Versatility in use.
3. High efficiency.
4. Manufacturability.

Thread dies

The combs are represented by multi-filament shaped cutters, which are of prismatic, round and rod type. Most often they are used for cutting threads with fine pitches and low profile heights.

Taps, dies and heads for thread cutting

The most widely used hand tools are for thread cutting. They can be used in industry and everyday life.

The most widely used versions are:

1. Similar tools are used to make bolts and studs. Such a product is a round washer, inside of which several ribs protrude. External threads can be formed and calibrated in just one pass. There are various versions of tools on sale; hardened tool steel is used in manufacturing.
2. Taps are used to produce internal threads. It is also manufactured using hardened tool steel, which is characterized by high wear resistance. The tap has the shape of a rod, the working part of which has several depressions and protruding edges. Due to this, the thread cutting process is significantly simplified.
3. Special heads can also be used to carry out the work in question. They can have different sizes and are used in conjunction with a special holder.

TapsThreading diesThreading head

The cost of hand tools is low, but they are characterized by high efficiency in use.

Recommendations for cutting turns on a water pipe are largely related to what technology is used. Hand tools for cutting external threads should be used taking into account the following information:

1. It is necessary to use lubricants that are added to the cutting zone to reduce the wear of the cutting edge.
2. At the time of work, you need to ensure that the tool is positioned strictly perpendicular to the workpiece. If it is displaced, the turns may be positioned incorrectly relative to each other.
3. When thread cutting, attention is paid to ensuring that chips are removed from the cutting zone in a timely manner.

Tapping a water pipe

The work in question can also be carried out in domestic conditions.

Dies are used to process the outer cylindrical surface. Among the features of its application, the following points can be noted:

1. The workpiece is secured in a vice. It must remain stationary during operation.
2. Before using the tool, the cutting edge and the surface being processed are lubricated with oil.
3. As a rule, a small chamfer is created on the end surface. It simplifies the process of screwing the die onto the surface to be treated.
4. During work, you need to pay attention to ensure that the die does not move. Because of this, the thread may be cut unevenly and the die stroke becomes more difficult.
5. For 2-3 turns along the thread, one turn is made in the opposite direction. This ensures the removal of chips from the processing zone and improves the quality of the resulting surface.

Die work

After completion of the work, the quality of the working surface is checked. To do this, just screw on the nut, which should have free play.

Clupp work

To carry out the work in question, a clamp can be used. It resembles a die, but is large in size. It is often used for cutting threads on pipes and is supplied in special sets with handles. Among the application features we note:

1. The clamp is characterized by high efficiency, so the process of cutting turns is simplified.
2. The instructions for using the die and die are almost identical, the only difference is how much force needs to be applied to obtain the required result.

Working with a manual clamp Electric clamp

A thread cutting kit is often represented by a combination of nozzles of various diameters. In the manufacture of the working part, wear-resistant material is also used, which does not dull during prolonged use.

Source: https://stankiexpert.ru/tehnologicheskaya-osnastka/instrument/instrument-dlya-narezaniya-rezbi.html

How to use a pipe thread cutter - rules for cutting threads

:

Any procedure for replacing a certain section of a pipeline involves inserting a new product. Welding can only be used on metal products; It is more convenient to connect plastic pipes using a threaded method, which involves the use of special devices for cutting threads.

General information about thread cutting

During the threading process, a rod or hole is machined. As a result, alternating protrusions appear on the surface - turns or spiral grooves.

The list of main thread characteristics includes:

1. Step. To determine it, you need to measure the distance between the peaks or valleys on adjacent turns.
2. Profile. The coil cross-section can be trapezoidal, triangular or rectangular. Sanitary type elements are equipped only with a triangular profile.
3. Profile angle.
4. Depth. Distance from the top to the bottom of the thread.
5. Diameter. Can be external, middle and internal.

To determine the outer diameter, you will need to measure the gap between two parallel sides of the thread. It is most convenient to carry out this procedure with a caliper at hand. The average diameter is the distance from the top to the base of the profiles located in opposite sections of the part. The internal diameter determines the distance separating opposite depressions from each other.

What are the threads on pipes?

Despite the simplicity of equipping a pipe with threads, it is definitely impossible to do without some recommendations. It is important to be able to distinguish between different types of threads, which can be left-handed, right-handed, inch and metric. Left-handed threads require a counterclockwise movement when screwing a nut onto a bolt. Accordingly, with a right-hand thread everything is exactly the opposite.

Metric thread characteristics:

• Millimeters are used to indicate the structural dimensions of individual elements.
• The profile looks like an equilateral triangle.
• The thread pitch is quite small.

Inch thread has the following features:

• The unit of measurement for designating dimensions is the inch.
• The profile looks like a triangle with equal hips and an apex angle of 55 degrees.
• Has a large step size. The profile of the inch thread is quite large, which gives the thread significant durable characteristics.

Each thread has its own specific purpose. However, right-hand threads are still used much more often than left-hand threads.

How to cut threads and what thread cutting tool is needed

Without the use of special devices, thread cutting on a pipe cannot be carried out. In plumbing stores, pipe threaders are sold under the name pipe threading kit. Quite often, such sets include rather unusual tools - clamps.

Externally, it is the same threaded die, but consisting only of the main functional element. This round frame has the shape of a short cylinder: it is most often made from tool steel. The cutters of this tool have significant strength and durability. The sets are also equipped with holders (ratchet or simple), as well as several additional devices such as pliers, clamps, etc.

When manually threading a pipe, you will need to observe the following points:

1. The pipe must undergo mandatory training. The area where the thread will be cut is cleaned of dirt, rust and paint. It is important to remove everything before the metal base appears.
2. As you apply threads to the pipe, be sure to lubricate the working surfaces and cutters of the tool used. This is done using liquid lubricant. It is applied at the beginning of the work, and as it progresses. At the end of the procedure, the lubricant should be wiped off well with a rag.
3. The end of the workpiece is first freed from the outer chamfer.
4. To achieve good quality, it is important to use a well-sharpened, working tool.

In addition to understanding the process, it is also important to know how to choose the right tool. Threads can be applied not only using the already mentioned dies and clamps, but also with taps. They make it possible to obtain internal threads by cutting grooves for chips. To apply a thread to the surface of a pipe, two similar tools are used at once, having different cutting depths:

• No. 1. Rough tap.
• No. 2. Finishing tap.

Source: https://trubaspec.com/soedinenie-trub/kak-ispolzovat-rezborez-dlya-trub-pravila-narezaniya-rezby.html

What is the name of the tool for cutting external threads?

A threaded connection is one of the most popular ways of fastening various parts and elements. It is not always possible to purchase various fasteners that already have threads applied, so you need to cut them yourself. For this purpose, specialized thread cutting tools are used. With their help, it is also possible to renew previously worn or otherwise damaged threads.

How to cut a tapered thread with a tap? — Metals, equipment, instructions

Any design cannot do without a threaded connection. To obtain an internal thread, a special tool was created, called a tap.

Many types of this tool have been developed. Each performs a specific function. Some of them are intended only for use on metal-cutting machines, others can be used in domestic conditions. Special tables have been created where you can select the right tool, depending on size, design and cost.

Threading Tool Design

The cutting tap consists of several parts:

• Shank;
• Working part;
• Fence element;
• Calibrations

Using a shank, it is mounted in a machine spindle or chuck when it becomes necessary to cut an internal thread.

The cutting is done by the working part. Its appearance resembles a screw, equipped with several helical and also longitudinal grooves.

A tool with helical grooves has one important advantage. The tapping operation is performed under more favorable conditions than performing the same operation with a thread tap that has longitudinal grooves.

Almost every instrument has a front part, which is given the name “fence”. It has a conical appearance. The intake part of the tool is the first to start threading. It is continued by the calibrating part. Its functions include calibrating and cleaning the hole.

The teeth used to cut threads are called cutting feathers . Their shape resembles incisors located along the entire diameter of the tool. Each tooth is sharpened according to the technological requirements for cutting parts.

The recesses that separate the cutting feathers from each other are called grooves. They form cutting edges, and chips are removed from the cutting zone along them. The dimensions of the grooves can be seen in the corresponding standardized tables.

Small parts with a diameter of less than 20 mm are equipped with three grooves. The tool has a maximum diameter of 40 mm and is manufactured with four grooves .

Metric taps

They are measured in millimeters and refer to the metric system. The instrument is marked with the letter "M", indicating a metric measurement. For example, the M8 marking means that this tool can produce an 8 mm thread.

The size range of metric taps has a wide range. Starting from 2 mm and ending with 60 mm . That is, you can cut absolutely any thread. All data about such a tool is summarized in special tables.

Depending on the purpose, the design of the tap is selected. They are divided into several groups:

For locksmith work, only hand tools . It, in turn, is divided into several types:

1. Nut;
2. Spot;
3. Uterine;
4. Special.

Locksmith

A set of such hand taps usually consists of three tools:

1. Chernovoy;
2. Average;
3. Finishing.

First, the “black” thread is cut, for which a roughing tap is used . To obtain thread accuracy, use a medium tap. The final cutting of the thread is carried out using a finishing tap and its calibration is carried out.

A special mark is made on the shank of each tap, by which the type of tap is determined. It can be digital or in the form of printed circular rings. The number of marks determines the purpose of the tap:

1. Chernova – one ring;
2. Finish - three rings.

In addition, the size of the thread that can be cut with this tap is marked on the tail.

Bench taps are supplied with two tools. They have a slightly longer intake cone, as well as an increased size of the first tap.

When cutting metric threads in the range of 8 - 18 millimeters, single taps are used .

For threads 6 - 24 mm, use two taps, one for roughing, the other for finishing.

Three taps cut threads in the range of 2 - 52 mm. Inch threads are also cut with several tools depending on the size. In more detail, what taps are needed can be seen in the guest table. It indicates the diameters, type of tap and the required kit.

Depending on the direction of the grooves, taps are divided into groups:

Moreover, the direction of the grooves also has different designs:

Tools with helical grooves are in most cases used for cutting very precise threaded holes.

The cutting part of the tool is divided into two types:

1. Conical;
2. Cylindrical

Conical

They differ in the design of the intake part, which is made slightly elongated and has an incomplete thread, which gradually becomes a calibrating part. These taps are used to cut threads in through holes.

Cylindrical

This tool cuts threads in parts where a through hole is not required.

When cutting nuts, nut devices are used without the use of machine tools . Thanks to the extended shank, the cut nuts remain on the tool.

The die parts have a large intake cone. With this tool, preliminary thread cutting is carried out in dies. The operation is performed in one pass. The threads are cleaned with master parts having grooves in the form of a right-hand spiral.

The main advantage of grooveless parts is their high productivity. They can cut threads in any holes. For such a tool, a through or blind hole does not matter.

Universal parts are manufactured as prefabricated parts. Each part is separated by a special neck. The roughing operation is performed by the first part, preliminary cutting is carried out, and the second part is done by finishing the thread.

Working with such equipment saves time . After all, only one tool is needed to cut threads. There is no need for a whole set, the installation of which requires a lot of additional time.

Pipe taps

Inches are taken for measurements, since pipes use a different system of change.

All pipe parts are marked with the letter G, which indicates pipe threads. Here are some examples:

• G 1/2 – half-inch thread;
• G 3/4″ – three-quarter;
• G1 – inch.

Half-inch pipe threads are most commonly used. This is especially true for plumbing in residential buildings, where the pipes are of such dimensions.

The pipe tap kit contains two parts. One has a sharp approach, the other is blunt.

As mentioned above, there are a lot of varieties of such instruments. Therefore, when making a choice, it is worth turning to special tables. They will tell you which tool you need to take, what diameter and what type.

• Vitaly Danilovich Orlov

Source: https://spb-metalloobrabotka.com/kak-narezat-konicheskuyu-rezbu-metchikom/

Thread cutting on a lathe - cutters, taps, dies, heads and dies

Thread cutting on a lathe is one of those operations for which various tools can be used. This problem is most often solved using a cutter. In addition to it, taps, dies, and special-purpose working heads are also used. In addition, on lathes this operation can be performed using knurling technology.

The process of cutting threads on a lathe with a cutter

Thread cutting using lathe equipment

When cutting a thread on a workpiece mounted on a lathe using a cutter, the process looks like this: the tool, moving along the axis of the rotating part (feed movement), draws a screw-type line on its surface with its pointed tip.

A characteristic parameter of the helix formed by the cutter on the surface of the workpiece is the angle of its elevation or increase.

The magnitude of this angle, measured between the tangent located to the helix and the plane, which is perpendicular to the axis of rotation of the part, is determined:

• the amount of feed of the cutting tool moving along the axis of the workpiece;
• the frequency at which the part rotates.

An equally important parameter of the helix is ​​its pitch, which characterizes the distance between its adjacent turns. This distance is measured along the axis of the workpiece.

Moving along the axis of the rotating workpiece, the cutter cuts into it and creates a helical surface, which is commonly called a thread. Elements with a threaded surface are used to solve various problems: ensuring the movement of elements relative to each other, their articulation and sealing of the formed joints.

The most common types of thread profile: a - triangular, b - rectangular, c - trapezoidal, d - persistent, e - round

The surface of the threaded workpiece can be cylindrical or conical. The characteristics of a threaded connection are significantly influenced by the thread profile, that is, its plane contour. Profiles are distinguished:

• triangular;
• trapezoidal;
• rectangular;
• persistent;
• round.

The thread on the surface of the part can be formed by one screw thread (single-start) or several (multi-start). If several screw threads are cut, then they are placed equidistant in relation to each other.

You can count the number of threads at the beginning of the threaded surface. A multi-start thread, in addition to the pitch, is characterized by such a parameter as stroke.

This is the distance measured between two similar points of two adjacent turns, which are formed by one thread. This distance is measured along a line parallel to the axis of the threaded part.

For a single-start thread formed by one thread, the stroke is equal to the pitch, but for a multi-start thread it can be calculated by multiplying the pitch by the number of starts.

All types of threads with diagrams, parameters and GOST regulations regulating them

Application of cutters

Thread cutting tools are required to cut threads using a lathe. They are made from high-speed steel, and the requirements for their characteristics are specified by the relevant GOST (18876-73). By design, such cutters are divided into the following types:

• prismatic;
• rod;
• round (disc).

A helical threaded groove on the surface of the workpiece is cut with a bent or straight cutter, and to form internal threads, straight and curved tools are required, which are fixed in a special mandrel. The top of the turning cutter, which is used to cut the turns, must have a configuration that fully corresponds to the profile of the thread being formed.

Cutters for cutting threads: a - rod; b - prismatic multi-profile; c - prismatic single-profile; g - disk multi-profile; d - single-profile disk; e - disk for internal thread; α—rear angle; γ — front angle; φ is the angle of the intake cone; h - installation height of the cutter axis

When forming a thread with a cutter, a number of features of this technology should be taken into account.

• The rake angle of a turning thread cutting tool depends on the characteristics of the material being processed. You can choose this angle within a fairly wide range: 0–250. So, if a thread is cut using a machine on workpieces made of ordinary steels, the rake angle should be 0 degrees; for high-alloy steels that withstand temperature loads well, the rake angle can be 5–100. It can be greater, the higher the viscosity of the material, and the smaller, the higher the hardness and fragility of the metal from which the workpiece processed on the machine is made.
• The tip of the turning tool, which forms a helix on the workpiece, must have a shape identical to the thread profile.
• The rear side corners of the tool are chosen such that the surfaces of the cutter with which they are formed do not rub against the newly formed helical groove. Typically these angles are made equal on both sides of the turning tool. If the helix angle that characterizes the thread is less than 4 degrees, then such angles are chosen in the range of 3–50; if more than 40, then 6–8 degrees.
• Internal threads are cut in already prepared holes, which are obtained by boring or drilling.

Workpieces made of steel are processed on a lathe using tools with plates made of hard alloys T15K6, T14K8, T15K6, T30K4. If the part is made of cast iron, then to cut threads on it, use a tool with plates made of the following grades of hard alloys: VK4, V2K, VK6M, VK3M.

Technology for using taps and dies

Using taps, which are a screw with several longitudinal grooves that form cutting edges and facilitate chip removal, predominantly metric threads are cut on a lathe in small-diameter holes. If machine taps are used for thread cutting, the operation is performed in one pass.

Machine taps differ from ordinary ones in that they consist of two parts - a tapping and a calibrating one. If ordinary taps are used to cut threads using a lathe, then the technology for performing this process involves the use of a set of tools.

The set for cutting internal threads includes three types of taps: roughing, which does 60% of the work, semi-finishing (30%), finishing (10%). Sometimes in such a set there may be two tools: roughing, which does 75% of the work, and finishing, which accounts for 25% of the work.

To distinguish a rough tap from a finishing one, just look at its cutting part: it is much longer than that of a finishing one.

Design of a tap for thread cutting

The speed of thread cutting on a lathe using taps can be quite high:

• 6–22 m per minute – for parts made of cast iron, bronze and aluminum;
• 5–12 m per minute – for steel workpieces.

Using dies, which are a ring with an internal thread and several chip grooves, external threads are made on screws, bolts and studs. The surface of the part must be pre-ground to the required diameter, which must take into account the tolerance:

• 0.14–0.28 mm – for threads with a diameter of 20–30 mm;
• 0.12–0.24 mm – for threads with a diameter of 11–18 mm;
• 0.1–0.2 mm – for threads with a diameter of 6–10 mm.

The dies with which external threads are cut are secured in a special chuck (die holder) located in the tailstock quill of the lathe.

Threading dies

 Using dies, threads are cut at the following speeds (their setting also takes into account minimal tool wear during operation):

• 10–15 m per minute – on products made of brass;
• 2–3 m per minute – on cast iron parts;
• 3–4 m per minute – on steel workpieces.

In order for the die to fit smoothly onto the part, a chamfer is removed at the end of the part, the height coinciding with the height of the thread profile.

Application of Die Heads

When cutting threads using lathes, special heads are used much less often than the tools described above. Such heads can be used for cutting threads of any type.

Their working elements are combs: prismatic ones are used when it is necessary to cut internal threads; for cutting external threads, radial, round and tangential ones are needed.

The peculiarity of such heads is that their working bodies automatically diverge during the reverse stroke, so they do not come into contact with the newly cut thread.

Threading combs

Combs for cutting internal threads (their number in a set may vary) are made with a lead-in cone. When cutting external threads, round type dies are mainly used, which are distinguished by the simplicity of their design. In addition, combs of this type are characterized by high durability; they can be sharpened repeatedly, bringing their geometric parameters to their original values.  

In the event that on a lathe it is necessary to cut a screw surface on worms or screws of great length, then the threading heads are fixed on the machine support, which helps to increase the productivity of the technological process. Such heads can be equipped with both conventional cutters and cup-type tools.

You can understand the technology of thread cutting using a lathe from a video that clearly shows how this process is carried out. Below are several videos that show the process of making carvings in different ways.

Source: http://met-all.org/obrabotka/tokarnaya/narezanie-rezby-na-tokarnom-stanke-rezcom.html

How to cut a tapered thread with a tap?

Forming threads on metal workpieces in the form of bodies of rotation is one of the most popular and at the same time complex turning operations.

The difficulty lies in both making basic equipment settings and preparing auxiliary tools.

In order for thread cutting on a lathe to comply with the technical specifications, you must adhere to the technology for its implementation and do not forget about safety rules.

Preparing the machine

Regardless of the type of lathe and working tool, carving will be done by machining.

Through the machine settings, the operator determines the angle of the helical line of influence on the surface of the workpiece, which will have a perpendicular position relative to the axis of rotation.

Here it should be noted that the machines have different power and, accordingly, spindle speeds - in order for the cutting tool to efficiently cope with its task, it is important to initially correctly correlate the angle of influence and the speed of the engine.

An important parameter is the step between the cutting lines - it is also taken into account in the equipment settings and appropriate adjustments are made in terms of the position of the tool relative to the workpiece.

Since thread cutting on a screw-cutting lathe is usually carried out in several approaches, it is advisable to save the primary parameters until the operation is completed.

Even if the step along the threading line is maintained, there remains a risk of violating the positions of the beginning and end of the deformation sections, which may not coincide with each other. It is important to keep these nuances in mind before starting work.

Types of thread

Turners distinguish between even and odd threads. In the first case, we are talking about cuts, which ultimately form an even number of cutting lines in steps. Accordingly, odd cutting leaves odd threads. From the point of view of the operation, even cutting threads on a lathe will have its advantages.

For example, after each approach, the operator can launch a sliding nut in the support and quickly return it back with the cutter manually, without stopping the operation of the equipment.

Then, with each new pass of the sliding nut, the tool will automatically be directed to the original cavity, which ensures a certain accuracy of the operation.

In turn, odd cutting requires, after each pass, the support to return to its original position along with the cutter, which cannot be done without starting the reverse stroke.

Multi-pass and vortex cutting can be placed into separate categories. So, in the first case, cutting multi-start threads on a lathe will require precise angular separation of the workpiece during transitions from one groove to another.

The initial calculation of the pitch and cutting line parameters is important here. As for the whirlwind thread, it requires additional installation of a rotating cutting head on the support carriage.

Several individual cutters can be fixed on it, each of which will cover its own area of ​​work.

Inch and metric cutting

Inch cuts are used for metal pipes. Typically, such threads are obtained from fittings, which are subsequently used to assemble a metal or plastic pipeline.

The standards for creating such cutting are determined by GOST 6357-81. Based on the technical document, we can conclude that the main parameters of inch cutting are pitch and diameter.

Moreover, the second characteristic is estimated as the distance between the extreme points of the thread ridges.

Typical cutting of inch threads on a lathe is carried out by cutters and taps with modifications of the technology as applied to internal processing.

Metric cutting is performed taking into account the same parameters, but the shape of the thread flange profile is added to them. In the case of inch cuts, it is most often sharp - in the shape of a triangle.

In addition, as the name suggests, classic pipe cutting is calculated in inches, while metric pipe cutting is calculated in millimeters.

Forming threads with cutters

A cutter is a tool that directly performs cutting. It is made of carbide steel and before work receives a special sharpening in a shape that meets the requirements of the task.

It can be used for threading bolts, nuts, studs and other workpieces. The cutter is installed in a machine chuck or multiple head.

The work process is divided into several passes - upon completion of each of them, the tool is moved to the side.

Correction of thread formation parameters in this case is carried out by adjusting the caliper, which sets the required depth. At the same time, there are standardized settings. In particular, cutting threads on a lathe with a cutter in increments of up to 0.2 cm will imply that the feed in the transverse movement of the caliper screw will average 0.1 mm per pass.

Simultaneous work with two cutters is also allowed. But here it is necessary to take into account a nuance that can affect the quality of the thread line - the chips released by the leading cutter will cling to the waste of the second tool, which will have, although insignificant, still an impact on the parameters of the edge being formed.

Application of dies

Dies are purposefully used to work with the same hardware in the form of bolts and studs, but only when creating external threads. The area that is planned for slicing is pre-processed and cleaned.

Also, the diameter of the threaded surface is calculated so that it is smaller than the outer diameter of the applied thread. In the case of metric technology, this difference can be 0.2 mm for small threads.

To form a thread entry, a chamfer corresponding to the height of the thread profile is first removed at the end of the workpiece.

Although the process itself can be carried out manually, most often machine threading with a die is performed on a lathe using a special die chuck. The cartridge itself is fixed in the rear quill or in a head socket with several mounting niches. The average speed of such cutting will be 5-6 m/min.

Application of taps

Taps are used specifically for working with metric threads applied from the inside. In this case, the diameter should be no more than 50 mm. Lathes usually use machine taps, which allow the operation to be completed in one pass.

This opportunity largely arises due to the one-time use of several tools that are installed in multi-purpose universal chucks.

If in the case of a conventional cutter the process is divided into several stages by passes, then thread cutting with a tap on a lathe can be segmented according to the quality of processing with different types of tools.

Again, they work simultaneously, following one after the other, which compensates for the load that falls on one cutter. There are taps for roughing and finishing threads. Moreover, the first tool removes about 75% of excess metal from the target ditch.

Cutting with Die Heads

To use several cutters at the same time, special heads with chucks are also used. This is a revolving tool, into which you can integrate the same screw-cutting attachments - tangential, radial and round.

After cutting is completed, their combs diverge on the reverse stroke and no longer contact the completed thread.

The most common are round cutters of this type, since they are capable of several sharpenings, have increased durability and are easier to maintain.

However, internal threading on a turret-type lathe is performed only with prismatic combs that have a special lead-in cone. To work with worms and long screws, cutting heads are used that are integrated directly into the machine support. They allow you to form both external and internal threads.

Features of internal thread cutting

Different types of screw-cutting equipment can work on such threads. Unlike surface external machining, such operations require the initial creation of a hole by drilling. In some cases, a corresponding boring is required, which will allow the thread to be used in the future to mate with parts of a specific diameter.

But if the diameter is calculated incorrectly, cutting an internal thread on a lathe can ruin the workpiece. This occurs in cases where the initial diameter itself matches the dimensions of the target part that is to be integrated into the target cavity. This can be avoided by allowing technological thickening of the internal walls before drilling. This tolerance must correspond to the height of the thread flange.

End of thread line

The quality of the created thread will be determined not only by the accuracy of the edges and the convergence of individual sections that were performed in different passes. It is also determined by how the thread lines are completed. The technology requires that the contour end with a special waste groove - it will ensure the free entry of the screw part.

Source: https://varimtutru.com/kak-narezat-konicheskuyu-rezbu-metchikom/