Fast thread cutting. What is the best way to cut a thread with a tap by hand? How to cut an internal thread

For threading, a variety of tools can be used, among which we highlight a tap. It is used to create a threaded surface designed to accommodate a screw, stud, bolt, or other fastener. Relatively low cost, ease of use determined the wide distribution of the considered hand tool. Let's take a closer look at how to properly cut a thread with a tap at home.

Classification of taps and their scope

For threading, for a sufficiently long period, lathes or drilling machines were used. They are designed to rotate workpiece or tool. The tap becomes the working tool in almost all cases.

The classification of such an instrument is carried out according to a number of different criteria:

As a rule, high-quality tool steel is used in the manufacture of tools. It can withstand long-term operation, does not heat up during operation. The high quality tap has a strict geometric shape and looks neat. A similar tool is often used for cutting metric threads, but there are options for obtaining inch threads. The shape of the base can be cylindrical or conical.

Preparatory stage

In order for the work on obtaining a thread not to cause many difficulties, careful preparation for such a technological operation should be carried out. All applied methods related with internal thread cutting, provide that a hole of the required diameter has already been obtained in advance. You can get a standard thread size when creating a hole according to the correspondence table. For example, for an M10 thread, a hole with a diameter of 8.5 mm is created.

Often there is a situation when a non-standard size thread should be obtained. In this case, the required hole diameter is calculated using the universal formula. The calculations are carried out as follows:

  1. The marking of the tool used is being studied. It is necessary to pay attention to the type of thread being cut, the pitch and the diameter.
  2. You can determine the required hole diameter when using the M5X0.75 tap as follows: 5−0.75=5.25 mm.

The easiest way to work is when you need to get a standard thread, since all the necessary information can be taken from various tables of regulatory documentation.

To get a quality hole, you need to choose the right drill. When drilling, it is recommended to use equipment that prevents the occurrence of runout during operation. When choosing a drill, it is worth remembering that it must have a high-quality sharpening. Experts recommend choosing the sharpening angle depending on the hardness of the material being processed. With increasing hardness index the recommended sharpening angle also increases, but it should not exceed 140 degrees.

Required equipment

Threading with a tap by hand only possible with the following tool:

After finding everything you need, you can proceed to the direct execution of work.

Features of the applied technology

Carry out the work in question you can do it yourself at home. To do this, consider the following recommendations:

It is not recommended to apply a large load to the handle by using a lever or gas wrench. Do not forget that the tap may burst due to high load, then remove the remaining the inside part will be quite difficult. AT While working, the master should feel how the tool goes: easily or with great effort. The shape of the cutting edge does not allow the removal of chips from the working part at the moment of rotation along the thread.

1. Preparatory work

The drilled hole in which the thread is cut with a tap must be machined or machined with a countersink. The diameter of the drill must be larger than the inner diameter of the thread, as the material is “squeezed out” a little when threading. For hard and brittle metals, the difference between these values ​​is less than for soft and ductile metals. For hard ones, for example, 6.7, and for soft ones - 6.8.

If we drill a hole with the same diameter as the internal threads, then the tap teeth will overheat due to high friction and build up with metal due to the material extruded during cutting. As a result of this, we will get a torn thread or simply break the tap.

If you drill a hole larger than the required diameter, you will get an incomplete thread.

2. Internal thread cutting

After the preparatory work, the workpiece is fixed in a vice and a tap is inserted vertically into its hole along the square.

Pressing the wrench to the tap with the left hand, turn it to the right with the right until the tap cuts several threads into the metal and takes a stable position, after which the wrench is taken by the handles with both hands and rotated with the interception of hands every half turn

In order to facilitate the work of the tap wrench, they do not rotate all the time in the clockwise direction, but one or two turns to the right and half a turn to the left, etc. Due to this reciprocating rotational movement of the tap, the chips break, it turns out to be short (crushed), and the process cutting is much easier.

Having finished cutting, by turning the knob in the opposite direction, the tap is unscrewed from the hole, then driven through it.

Cutting Fluids for Threading
Processed material Lubricating fluid
Carbon steel Emulsion. Sulfurized oil
Structural steel Sulfurized oil with kerosene
Tool steel Blended oils
Ductile iron 3-5% emulsion
Cast iron B / o. 3-5% emulsion. Kerosene
Bronze B / o. Blended oils
Zinc Emulsion
Brass B / o. 3-5% emulsion
Copper Emulsion. Blended oils
Nickel Emulsion
Aluminum and its alloys B / o. Emulsion. Mixed oils. Kerosene.
Stainless, high temperature alloys

50% sulfurized oil, 30% kerosene, 20% oleic acid

(80% sulfofresol, 20% oleic acid)
Fiber, vinyl plastic, plexiglass 3-5% emulsion
Textolite, getinaks Compressed air blowing

3. Rules for threading with a tap

  1. When cutting threads in deep holes, in soft and ductile metals (copper, aluminum, bronze, etc.), the tap must be periodically unscrewed from the hole and the grooves must be cleaned of chips;
  2. Thread should be cut;
  3. Threading immediately with an average tap without a roughing pass, and then with a finishing one does not speed up, but, on the contrary, makes the work more difficult. The thread in this case is of poor quality, and the tap may break. The middle and finishing taps are inserted into the hole without a wrench, and only after the tap passes correctly along the thread, the wrench is put on the head and threading continues;
  4. A blind hole for the thread must be made to a depth slightly greater than the length of the cut part, so that the working part of the tap goes slightly beyond the cut part. If there is no such stock, the thread will be incomplete;
  5. In the process of cutting, it is necessary to carefully monitor that there is no distortion of the tap; for this it is necessary to check the position of the tap in relation to the upper plane of the product with the help of a square every 2-3 threads cut. Especially carefully you need to cut the thread in small and blind holes;
  6. Thread quality and tool life are affected by the correct choice of cutting fluid

The question of how to cut threads with a tap arises when a pre-made hole needs to be prepared to accommodate a bolt, screw, stud, and any other type of threaded fastener. It is the tap in such situations that is the main tool that allows you to quickly and accurately cut the internal thread with the required geometric parameters.

Varieties and scopes of taps

Internal threading can be done manually or using machines of various types (drilling, turning, etc.). The working tools that perform the main work of cutting internal threads are machine-hand or machine taps.

Taps are divided into different types depending on a number of parameters. The following principles for classifying taps are generally accepted.

  1. According to the method of bringing into rotation, machine-manual and machine taps are distinguished, with the help of which the internal thread is cut. Machine-hand taps equipped with a square shank are used in a set with a special device with two handles (this is the so-called wrench, tap holder). With the help of such a device, the tap is rotated and cuts the thread. Threading with a machine-type tap is carried out on various types of metal-cutting machines, in the chuck of which such a tool is fixed.
  2. According to the method by which the internal thread is cut, universal (through) and complete taps are distinguished. The working part of the former is divided into several sections, each of which differs from the others in its geometric parameters. The section of the working part, which first begins to interact with the machined surface, performs roughing, the second - intermediate, and the third, located closer to the shank, - finishing. Threading with complete taps requires the use of several tools. So, if a set consists of three taps, then the first of them is intended for roughing, the second for intermediate, and the third for finishing. As a rule, a set of taps for cutting threads of a certain diameter includes three tools, but in some cases, when products made from especially hard material are processed, sets consisting of five tools can be used.
  3. According to the type of hole on the inner surface of which it is necessary to cut the thread, there are taps for through and blind holes. The tool for processing through holes is characterized by an elongated conical tip (entry), which smoothly passes into the working part. Such a design is most often used for taps of a universal type. The process of cutting internal threads in blind holes is carried out by taps, the conical tip of which is cut off and performs the function of a simple milling cutter. This design of the tap allows you to cut threads with it to the entire depth of a blind hole. For threading this type, as a rule, a set of taps is used, which are driven manually using a wrench.
  4. According to the design of the working part, the taps can be with straight, helical or shortened chip removal grooves. It should be borne in mind that taps with grooves of various types can be used for cutting threads in products made of relatively soft materials - carbon, low-alloy steel alloys, etc. steels, etc.), then for these purposes taps are used, the cutting elements of which are arranged in a checkerboard pattern.

Taps are usually used for cutting metric threads, but there are tools that cut pipe and inch female threads. In addition, taps also differ in the shape of their working surface, which can be cylindrical or conical.

Preparing for internal threading

In order for the process of cutting an internal thread with a tap not to cause any particular difficulties and to end with a quality result, it is necessary to properly prepare for this technological operation. All methods of threading with a tap assume that a hole with the appropriate diameter has already been made in the workpiece. If the internal thread to be cut has a standard size, then a special table with GOST data can be used to determine the diameter of the preparatory hole.

Table 1. Hole diameters for standard metric threads

In the event that the thread to be cut does not belong to the standard category, the diameter of the hole for its execution can be calculated using the universal formula. First of all, it is necessary to study the marking of the tap, which necessarily indicates the type of thread being cut, its diameter and pitch, measured in millimeters (for metric). Then, to determine the size of the cross-section of the hole to be drilled for the thread, it is enough to subtract the pitch from its diameter. For example, if a tool marked M6x0.75 is used to cut a non-standard internal thread, then the diameter of the preparatory hole is calculated as follows: 6 - 0.75 \u003d 5.25 mm.

For standard threads belonging to the inch category, there is also a table that allows you to choose the right drill with which to perform the preparatory work.

Table 2. Hole diameters for inch threads

Important for obtaining a high-quality result is the question not only of what the thread is cut with, but also of which drill to make the preparatory hole. When choosing a drill, it is necessary to pay attention to the parameters and quality of its sharpening, as well as to ensure that it rotates in the chuck of the equipment used without beating.

The sharpening angle of the cutting part is selected depending on the hardness of the material to be drilled. The higher the hardness of the material, the greater the sharpening angle of the drill should be, but this value should not exceed 140 °.

How to cut a thread correctly? First you need to pick up tools and supplies:

  1. an electric drill or drilling machine capable of operating at low speeds;
  2. drill, the diameter of which is calculated or selected according to reference tables;
  3. a drill or countersink, with which a chamfer will be removed from the edge of the prepared hole;
  4. a set of taps of the appropriate size;
  5. manual holder for taps (knob);
  6. bench vise (if the product in which the thread is to be cut must be fixed);
  7. core;
  8. a hammer;
  9. machine oil or other composition, which during the processing process needs to lubricate both the tap and the thread section cut by it;
  10. rag.

Technology features

When cutting an internal thread with a tap, the following algorithm is used.

  • In the place on the surface of the workpiece where the hole for threading will be drilled, it is necessary to form a recess for a more accurate entry of the drill using a core and a conventional hammer. The drill is fixed in the chuck of an electric drill or drilling machine, on which low rotational speeds of the tool are set. Before starting drilling, the cutting part of the drill must be treated with a lubricant: the lubricated tool enters the structure of the material being processed more easily and creates less friction in the processing area. You can lubricate the drill with a piece of ordinary lard or grease, and when processing viscous materials, machine oil is used for this purpose.
  • If it is necessary to cut threads in small parts, they should be pre-fixed using a bench vise for this. Starting drilling, the tool fixed in the equipment chuck must be positioned strictly perpendicular to the surface of the workpiece. You should regularly lubricate the tap and make sure that it does not warp and moves strictly in the specified direction.
  • At the entrance to the hole, as mentioned above, it is necessary to chamfer, the depth of which should be 0.5–1 mm (depending on the diameter of the hole). For this purpose, you can use a larger diameter drill or countersink by installing them in the chuck of drilling equipment.
  • The process of cutting internal threads begins with tap # 1, which is the first to be installed in the knob. We should not forget about the lubricant, which must be applied to the tap for threading. The position of the tap relative to the hole to be machined must be set at the very beginning of work, since later, when the tool is already inside the hole, this will not work. When cutting a thread with a tap, it is necessary to adhere to the following rule: 2 turns of the tap are made in the direction of threading, 1 - against the course. When the tap is made one turn back, chips are dropped from its cutting part and the load on it is reduced. Threading with a die is performed using a similar technique.
  • Having cut the thread with tap No. 1, tool No. 2 is installed in the knob, and after it - No. 3. They are processed according to the method described above. When threading with taps and dies, you need to feel when the tool starts to rotate with force. As soon as such a moment comes, you should turn the knob in the opposite direction to throw chips from the cutting part of the tool.

R Threaded connection is one of the most common ways of fastening various parts. Today there are many varieties of bolts, nuts, screws, etc., but sometimes there are situations in which you need to cut the thread yourself, for example, in a hole made in metal or on a metal water pipe. To do this, there are several tools and methods for threading, let's look at them.

Content:
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3.1
%0A 3.2%20 The principle of cutting threads with a die.
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Carving happens:

  • Metric
  • Inch
  • Pipe inch

How they differ can be seen in the picture below, it is worth noting only one thing, which is mainly used metric thread.

There is also a difference between right and left hand threads.

Likbez: what you need to know when cutting threads by hand

How to cut external threads with a die

To cut external threads manually, a special tool is used - a die holder with dies of various diameters.

In hard-to-reach places, for example near walls, a ratchet die holder is used.

Die selection

The nominal thread diameter is the diameter at the vertices of the thread triangles. The die cuts the metal, forming depressions and leaving the peaks intact, thus both the rod and the die must be of the same diameter. The thread diameter, for example, is M3 - this is “M” - a metric thread, and the number is the nominal thread diameter in mm. Accordingly, in order to cut a thread on a 3 mm rod, we take an M3 die. The measurements of the rod are carried out with a caliper.

In order for the die to better cut into the rod, a chamfer is cut off from its end.

Thread cutting principle

A vise is required to secure the workpiece. The workpiece is firmly fixed in a vise and lubricated with machine oil for easier die movement, reducing friction and tool wear.

When cutting threads with a die, a large accumulation of chips in the chip removal holes should be avoided.

The die is installed on the end face of the part perpendicularly. With a little pressure, they begin to rotate the die holder clockwise, if the thread is right-handed, respectively, if left-handed, then counterclockwise.

Cut the thread as follows:

  1. First make 2-3 turns.
  2. Then half a turn back to remove chips.
  3. Lubricate after every 3-4 turns, you can use a syringe.
  4. Etc.

Threaded connections are used in the manufacture of a wide variety of products. This is due to the fact that it can be cut independently using inexpensive equipment. Before applying coils to the surface of the product, you should consider the main points regarding certain parameters. A high-quality thread is characterized by a tight connection and high reliability. Let us consider in more detail the process of cutting coils on pipes.

Preparing for hand carving

Threading pipes at home can be done using improvised tools. The basic rules for preparation are as follows:

  1. At the place where the coils are cut, dirt, rust and other pollutants are removed. This recommendation is due to the fact that foreign elements can degrade the quality of the turns.
  2. If there is a chamfer on the pipe, then it is carefully removed with a file. In some cases, this process is carried out by a grinder, but the quality of the resulting chamfer may be low. Therefore, if there is no need to rush, then it is best to work with a file.
  3. At the time of work, the surface must be well lubricated with oil. Only in this case it is possible to ensure the smooth running of the mechanism used.

Step-by-step instructions for threading with a die

The most common can be called a die of various types. It is one of the necessary tools for cutting coils. Among its features, we note the following points:

  1. The die looks like a nut made of hardened steel. From the end sides there are holes made in the form of a flower. To ensure machining, the edges are represented by sharp cutting edges. Due to the petal shape, chip removal from the cutting zone is ensured.
  2. There are holes in the body for mounting the handle. They are located on the sides, due to which a uniform impact is ensured.

The die has become widespread due to the fact that it is quite easy to use. Recommendations for its use are as follows:

  1. At the time of processing, the pipe must be vertically located. At the same time, it is fixed with a vice.
  2. It is recommended to clean the surface, as well as create a chamfer.
  3. Oil should be applied to the pipe, which will simplify the passage of the die through the pipe.
  4. It should be borne in mind that the die must be located strictly vertically. Even with a deviation of only 10 degrees, it will lead to a decrease in the quality of the resulting turns.
  5. The handle should be rotated clockwise.
  6. In order to improve the quality of the resulting surface, one reverse should be done after two turns, which ensures the removal of metal residues from the cutting part.

During work, periodically lubricate the working part and the pipe with oil. Lubricants make cutting easier and smoother.

Threading set for pipes and how to use it

You can significantly simplify the task of threading by purchasing a special set for pipes. It is ideal for home use. An example is a klupp - a slightly modified die, which is used together with a ratchet and a guide. The kit may include various devices:

  1. Monolithic are represented by a cylindrical body with an internal hole. For work, a special die holder is also included in the kit.
  2. Sliding ones consist of incisors, the distance between which can be adjusted if necessary. It is used for cutting a threaded surface in several passes, thereby improving the quality.

Lerka is selected depending on the diameter of the pipe and the direction of the thread. The cutting process is characterized by the following features:

  1. A special tool, called a klupp, is installed in a ratchet.
  2. Oil is also applied to the cutting part, which simplifies the movement of the working part.
  3. A guide is installed on the edge of the processed pipe.
  4. The ratchet rotates around the axis, due to which the thread is formed.
  5. During machining, oil is added from time to time.

It is worth considering the moment that the device after prolonged use may become dull. That is why you need to monitor the condition of the cutting edge.

Threading a pipe near a wall

Most of the problems arise with threading on a pipe that is located near the wall. This is due to the location of the workpiece and the lack of free space. That is why a common question can be called how to cut a thread on a pipe.

In this case, processing is carried out using similar tools. However, threading a pipe near a wall is often only possible if the wall is partially removed. Among other features of the procedure, we note the following points:

  1. If you need to cut a thread on one of the sections of the pipeline, then it is recommended to dismantle it first. In some cases this is possible.
  2. For cutting pipe threads, a fairly large amount of oil is also required, which facilitates the movement of the device. However, when the pipe is horizontal, it begins to drain quickly, which creates significant problems with the process under consideration.
  3. The thread is made in several passes, which ensures a high surface quality.

Cutting a thread on a water pipe when it is in a horizontal position is quite difficult. This is due to the fact that it is quite difficult to control the strict location of the applied mechanism parallel to the axis, as well as to provide the required load.

How to cut an internal thread?

In some cases, an internal thread is required, which can also be cut using a hand tool. Often, for such work, a tap is selected, which consists of three main parts:

  1. Fence.
  2. Calibrating.
  3. Tail.

The intake is applied directly at the moment of cutting, the calibrating guides the tool and ensures its vertical position. The tail section is required in order to fix the die in a special holder.

An internal thread can be formed as follows:

  1. The pipe is fixed in a vertical position.
  2. The tap of the workpiece being processed is lubricated.
  3. The device is placed strictly vertically, after which several rotations are made clockwise, and one against.

At the time of work, oil should be added from time to time. This ensures a smooth running of the tool.

Gutter cutting machine

In production, special machines are often used. In terms of design features, they are in many ways reminiscent of machines with a vertical orientation. Among the features we note:

  1. Diameter index and thread pitch are adjustable.
  2. If necessary, you can carefully adjust the number and speed of rotation of the cutting element.
  3. Almost all models are characterized by the possibility of processing the outer and inner surfaces.

Modern machines can be used even when cutting thin-walled products. Difficulties can arise only when the workpiece cannot be removed and installed vertically.

Basic cutting methods

There are two main ways to cut coils on the surface to be treated: manually or using automatic equipment. In home workshops, hand tools are often used, as they are cheap and easy to use. The most commonly used die, on sale are the following:

  1. Klupp.
  2. Whole.
  3. Split.

The main part of the fixture can be made in the form of a square and hexagons. The most widespread are disk versions, which are used for threading.

Split or spring-loaded versions are characterized by high wear resistance. However, the features of their design determine that it is practically impossible to achieve high accuracy and purity of the cut turns.

You can also use sliding dies, which often consist of two working parts. This ensures versatility in application.

Thread cutting technique

As previously noted, the klupp is represented by a modernized die, which has adjustable cutters. In addition, the cutting part can be replaced if necessary and extend the life of the tool.

On sale you can find a manual version, as well as an electric one. Hand tools are more common, they are easy to use and inexpensive.

Electric are characterized by high performance. Klupp is installed in a different position, but most often in a vertical position.

Cutting with a hand screw

  1. The working part is installed in a special holder made in the form of a ratchet. It greatly simplifies the process of cutting coils on the surface of the pipe.
  2. You can start work by cleaning the pipe. It should be borne in mind that when cutting turns, it is possible only in the absence of strong defects.
  3. Surface cleaning is carried out to the metal until it begins to shine.
  4. The outer edge is machined to obtain a chamfer. This ensures the entry of the tool.
  5. The surface is treated with technical vaseline. It reduces the degree of friction, makes the tool run smoother.
  6. The pipe is fixed in a vice, you can hold it with a gas wrench. It is important to exclude the possibility of tilting or displacement of the pipe when a high load is applied to it.

The work involves making several turns clockwise, and then in the opposite direction. This is done in order to remove chips from the cutting zone.

Cutting with an electric screw

In addition to hand tools, electric tools are also widely used. The advantage of this embodiment can be called high performance. Work with its application has the following features:

  1. The part to be processed is carefully prepared.
  2. Provides reliable fastening of the workpiece.
  3. The mechanism is fixed at the starting point.
  4. The free movement of the guides and the direction of rotation of the cutting part are checked.
  5. The first turns are cut in jog mode.

On the tool, you can set the basic parameters, for example, the length of the cut. Application features depend on its functionality and other performance characteristics.

The procedure for cutting external threads on a water pipe

Water pipes are found in almost every residential and commercial building. The sequence of actions for threading is as follows:

  1. Training. At the preparatory stage, the main thing is to remove all dirt and possible rust, as well as remove all defects. Otherwise, it may be difficult to carry out the work.
  2. Workpiece installation. The pipe must be located strictly vertically, otherwise the die may move to the side.
  3. Cutting. At this stage, it is necessary to monitor the strictly vertical arrangement of the mechanism used, since even a slight displacement can lead to significant problems.
  4. Quality checking. This stage involves screwing the nut, due to which the cleanliness of the turns and the accuracy of their location are checked.

When using a lathe, it is possible to create turns in one longitudinal pass. However, screw-cutting lathes are not the best suited for the task at hand.

On stainless pipe

Often, stainless steel is used in the manufacture of pipes. It is characterized by high strength and corrosion resistance. However, the presence of a large amount of alloying elements leads to a decrease in the degree of machinability. That is why there can be quite a few difficulties with threading.

You can simplify the cutting process with the abundant use of a lubricant. In addition, you need to choose a die or tap made of wear-resistant material that will not dull during processing.

In conclusion, we note that it is not necessary to have any skills or have special tools to obtain threads on the surface of pipes. It is important to use the selected threading mechanism correctly, as well as monitor the presence of lubricant. It should be borne in mind that an insufficient amount of lubricant can lead to jamming of the die or tap.

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