How to cut internal threads

How to cut threads

Threads are one of the most convenient detachable connections, and therefore information on how to cut threads may be useful in the household. There are inch and metric threads, so it happens that a screw that seems suitable at first glance turns out to be unsuitable - the diameter is not the same and the thread pitch is different. Even the profiles of metric and inch threads are different: the apex angle in a metric thread is 60 degrees, and in an inch thread it is 55 degrees.

Any threaded connection consists of two parts, one of which has an internal thread in the hole, and the second has an external thread on a cylindrical surface. Mostly they use right-handed threads, in which rotation occurs clockwise, but sometimes left-handed threads with counterclockwise rotation are also found.

For a thread, the main dimensions are the pitch - the distance between its turns) and the outer diameter. They are interconnected and are standard. Both internal and external threads are determined by the size of the diameter of the rod, that is, if an M10 thread is indicated, then this thread is metric, right-handed, with a screw diameter of 10 mm and a thread pitch of 1.5 mm.

Sometimes non-standardized threads are used, for example, camera lenses are mounted on threads with a diameter of 42 mm. According to the standard, the pitch for this thread is 4.5 mm, but for an optical device this is too large a parameter, so a pitch of 1 mm is used. There are special standards for small threads.

Basic thread sizes can be found in reference books and standards.

Any threads are cut using special tools and machines, and at home you can cut internal and external threads on fasteners with a diameter of up to ten millimeters. To do this, use a simple tool such as sets of dies (for external threads) or taps (1) (for internal threads). The dies (2) are a carbide tool, similar to a nut with cutting grooves.

Taps (1) are also made of carbide; this tool is similar to a screw with cutting grooves. Typically, not one tap is used, but a set of two or three tools that are used for roughing and finishing passes, and have different depths for cutting thread grooves. When cutting threads, both taps and dies are clamped into special devices - cranks (3), the size of which must be suitable for the tool used.

Tools for cutting threads must be of high quality and sharp. It will be impossible to cut a good thread with a dull rusty tap, and there is a high probability that it will break in the first hole, and in this case there will be more problems with its removal from the workpiece. Low quality metal taps are only suitable for working with plastic. As for dies, a blunt tool will cut uneven threads, and then the nut can only be screwed on with great effort.

External thread cutting

A round metal rod with a diameter equal to the diameter of the required thread is firmly clamped in a vice in a vertical position. At the end of the workpiece, use a file or a velvet file to chamfer the tool and generously lubricate the workpiece with machine oil to facilitate thread cutting.

A suitable die is secured in a special driver and begins to be put on the end of the workpiece. The tool is screwed onto the workpiece, making sure that there are no distortions. With a right-hand thread, after one or one and a half turns clockwise, the die must be turned half a turn in the opposite direction.

This is how the entire required thread length is passed until the work is completed.

Internal thread cutting

First, a hole of the required diameter is drilled in the workpiece and a chamfer is removed to allow the tool to fit in. The drill diameter is selected according to reference data. The holes in the workpiece can be through (throughout the entire thickness of the part) or blind. If a hole with an internal thread of a short length is required, then in this case a hole of a greater length than the thread is drilled, since the taper of the tap in the lower part must be taken into account. Allowances for drilling depth should also be taken into account.

For greater profile cleanliness, internal threads are formed using three taps. The first of them forms a preliminary passage; it is indicated by a mark in the upper smooth part of the tool. The second tap from the set completes the thread formation (it is indicated by two marks), and the third tool finally forms the thread profile, it is indicated by three marks. In this way, the thread is cut gradually, resulting in a clear profile.

For holes up to three millimeters in diameter, use a set of two taps. The process of cutting threads is the same as when working with dies - repeating forward and backward movements to break chips from the tool using lubricant. If the thread is cut in blind holes, then it is advisable to periodically turn the tap out to completely remove metal filings from its surface.

They are removed with an old toothbrush or cloth, and then you need to lubricate the tool again and continue cutting the thread until it stops.

Adviсe

• If the thread accidentally becomes dented during work, it can be restored by holding the part in a vice and driving the thread again with a tap or die.
• If you need to further lengthen the surface of a threaded screw, you must ensure that the die easily fits along the existing threads and does not spoil its profile.
• To prevent the thread from corrosion, it can be lubricated with petroleum jelly.
• If during cutting there is a skew and the external thread “goes” to the side, then you can cut off a piece of the rod and start the process again.
• If the tap breaks in a hole, and it is not possible to drill another hole nearby, you can remove the broken tool in several ways. If part of the tap remains sticking out, then its end is ground into the shape of a spatula and turned out with pliers. And if part of the tap remains inside, then use nitric acid and a wooden stick: a drop of acid is applied to the broken tap and wait until the acid destroys its cutting edges. Then the fragment is pulled out with tweezers or knocked out from the other side of the hole (if it is through).

Evaluate the manufacturing method:

Source: http://sdelai-sam.pp.ua/?p=8375

Cutting external and internal threads on pipes: tools, technologies

Threading a pipe is the processing of its internal or external surface to produce alternating helical grooves and protrusions. Threads are formed on pipes, fasteners, and equipment parts.

Main characteristics of threads

To determine the thread size, the following parameters are used:

• Profile – rectangular, triangular, trapezoidal. The triangular profile is used when installing sanitary systems.
• Profile angle – formed by the side edges of the turns.
• Direction – right or left. With the left one, the nut is screwed onto the bolt counterclockwise, with the right one - clockwise. The right one is much more common.
• Pitch is the distance between the tops or bases of adjacent turns.
• Depth is the length of the segment from the top to the deepest point.
• Internal diameter is the distance between the thread bases located at opposite points of the cross-section of a rod or hole.
• Outer diameter is the distance between the thread tips located on opposite sides.
• The average diameter is the size of the segment between the top and the base, lying on opposite sides.

According to the system of measures, triangular threads are divided into metric and inch.

Metric

They have the shape of an equilateral triangle with angles of 60°. The internal and external diameters are indicated in millimeters, the pitch - in millimeters and their fractions.

Inch

The profile is similar to metric threads, but the apex angle is not 60°, but 55°. The size is expressed in inches, the pitch differs from its metric counterparts. Threads are divided into pipe and fastening threads; they are in demand when installing plumbing systems. The fastener has a large pitch, is used for nuts, bolts, studs, holes, and guarantees reliable joining of parts. Pipe has a smaller pitch and is used to connect pipes.

Basic rules for cutting pipe threads by hand

A thread-cutting set is designed for cutting external threads manually. It consists of:

• dies or die - frames, which are a cylinder made of tool steel, equipped with durable cutters;
• holder with or without ratchet;
• pliers, clamps and other auxiliary tools.

Taps are used to make internal threads.

Basic requirements that must be met when cutting threads by hand:

• surface cleaning;
• the working surfaces of the tool and the processed elements are lubricated with special liquids;
• the instrument must be in full working order.

How to choose a tool for cutting external threads at home?

To make external threads on a pipe, a die is used - a piece made of tool steel that has a rounded shape. There are cutting edges inside it. Using a special holder, a double handle is attached to it, providing convenient rotation. The pipe die is an improved version of the die.

Its feature is the saving of expensive steel grades, since the working element is placed in a holder made of cheaper metal. An additional plus is the single handle, which allows you to cut threads in hard-to-reach places. The cutters in the die are replaceable parts that can be purchased separately as they wear out.

Advice! It is recommended to purchase cutters from the same manufacturer as the tool. If this is not possible, then you should take the holder with you to the store to make sure that the body and cutting parts fit together accurately.

The type of clamp is chosen depending on the amount of work and personal preferences.

• The simplest hand tool consists of a holder with cutters fixed in it and a handle, which in the cheapest models is not included in the basic kit. To rotate the clamp without a handle, you will need a pipe wrench. The handles can be rotated with two hands or with one. The second option is more convenient for working in cramped conditions. With this compact and inexpensive tool you can carry out work in small quantities.
• Manual clamp with ratchet. The tool is convenient in that it is not necessary to remove the handle after each turn of the holder. This option is more financially expensive compared to the previous one, but more convenient, reliable and productive.
• Electric models are easy to use and allow you to carry out large-scale work. Significant disadvantages are: inability to use in hard-to-reach places, the need for a nearby power source, dependence on weather conditions when working outdoors.

To simplify the process of making threads, apply a little diesel fuel or grease to the contacting surfaces.

Approximate scheme of work

• The clamp is put on the pipe and fixed.
• Rotate the handle while pressing simultaneously.
• When working with old pipelines, in order to avoid breaking off part of the pipe, the stress from rotational movements is compensated using a pipe wrench.

Features of cutting internal threads on a pipe using a tap

To make internal threads on a pipe, a tap shaped like a rod with a cutting element is used. Inserted into the collar. Structural parts of the tool:

• fence - has the shape of a cone, produces cutting (cutting teeth are incisors located in a circle);
• calibrating - has the form of a cylinder with teeth, which are a continuation of the teeth of the intake part;
• tail with a square head - holds the tap in the gate or chuck of the machine.

Recommended Cooling Media:

• for aluminum and alloys based on it - kerosene;
• for copper - turpentine;
• for steel – emulsion.

If there is no or insufficient amount of coolant, a rough or uneven profile may form.

Source: https://www.navigator-beton.ru/articles/narezka-rezby-na-trubah.html

How to cut a thread with a die or tap, incl. on pipes

A threaded connection is one of the most common methods 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 threads yourself, for example, in a hole made in metal or on a metal water pipe.

There are several tools and thread cutting methods for this, let's look at them.

:
1. Types of thread.
2. Educational program: what you need to know when cutting threads by hand.
3. How to cut external threads using a die.
3.1 The principle of cutting threads with a die.
3.

3 Cut the thread with a die with your own hands (video).
4. Cutting internal threads with a tap.
4.1 Manual cutting of internal threads with a tap (video).
5. Cutting threads on a metal pipe with your own hands.
5.1 Cutting external threads on a pipe using a die (die).
5.2 What is a clamp and how to use it (video).

5.3 Cutting internal threads on a pipe with a tap.

Types of thread

The carving is:

• Metric
• Inch
• Pipe inch

How they differ can be seen in the picture below; the only thing worth noting is that metric threads are mainly used.

Types of thread

There is also a difference between right and left threads.

How to cut external threads using a die

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

Die holder with dies for different diameters

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

Selection of dies

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

To make the die cut better into the rod, a chamfer is cut off from its end.

Principle of thread cutting with a die

To secure the workpiece you will need a vice. The workpiece is firmly fixed in a vice and lubricated with machine oil for easier movement of the die, reducing friction and tool wear.

When cutting threads with a die, you must avoid large accumulations of chips in the chip removal holes.

The die is installed on the end of the part perpendicularly. With slight pressure, they begin to rotate the die holder clockwise if the thread is right-handed, respectively, if it is 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, using a syringe.
4. Etc.

Source: https://chonemuzhik.ru/kak-narezat-rezbu-plashkoj-ili-metchikom-vt-ch-na-trubax.html

How to cut a thread manually with a tap correctly: tool classification and basic recommendations - Machine

Lathes or drilling machines have been used for cutting threads for quite a long period. They are designed to rotate a workpiece or tool. In almost all cases, the working tool is a tap.

The classification of such a tool is carried out according to a number of different characteristics:

1. Depending on the method of driving them into rotation, they can be divided into machine or machine-hand taps. A special feature of the machine-manual variety of the tool is the presence of a square shank, which is suitable for a holder with two handles. Thanks to such a holder, you can rotate the tool and cut threads. As for the machine variety of the tool in question, it is installed in the chuck of various machines and can have a shank of various shapes and sizes.
2. There are universal and complete taps based on characteristics related to the specific application. The universal version has a working part, which is divided into several sections. They differ from each other in geometric shape, the first is intended for roughing, the second and subsequent ones are for bringing the surface to a suitable state. The complete version is designed for the phased use of several taps. As a rule, a set for cutting threads in ordinary metal is represented by three tools, and for processing hard alloys - five.
3. Taps are classified based on the type of hole being machined: blind or through. To work with through holes, a tool with an elongated conical tip is used, which is a continuation of the working part. Universal taps often have this type of shape. If you need to cut a thread in a blind hole, then use a tool that has a cut tip resembling a milling cutter. Due to this shape, it is possible to cut threads along the entire length of the hole.
4. Thread cutting tools are also classified according to the type of working surface. Examples include helical, straight or shortened grooves. On sale you can find a version that also has a combined surface. It is suitable for processing metals with low hardness. For hard alloys, a tool with cutting elements arranged in a checkerboard pattern is used.

: Gray color in the interior - let's analyze it thoroughly

Drill selection

An electric drill is necessary to perform internal threading work.

Before cutting a thread with a tap, you must first drill a hole for it. It is absolutely clear that the diameter of the hole should be smaller than the size of the tap, but how much? There is a universal way to calculate this difference. Any thread is characterized by two parameters:

• diameter, indicated on instruments with a capital letter M in front, for example, M6;
• The pitch of turns is written as a number after the first parameter, for example, M6x1.

By looking at the markings on the tap, it is easy to select the drill for the job. It is necessary to subtract the thread pitch from the diameter value; in the given example, M6x1, you will need a hole measuring 6 - 1 = 5 mm.

The drill should be a regular cylindrical one; for metal processing, these are made from high-speed steel R6M5.

In order to facilitate the selection of sizes, Table 1 presents the recommended diameters for the holes of the most common metric profile threads.

Table 1

Marking	M3	M4	M5	M6	M8	M10
Hole D, mm	2,5	3,3	4,2	5	6,75	8,5

Since we are talking about manual metal processing, one feature should be taken into account when selecting drills.

When working with an electric drill, no matter how hard you try to keep it level and motionless, the hole will break and its size will be slightly larger than necessary. As a result, after passing with a tap, the thread turns will have a cut profile.

When the bolt is screwed in, there will be some play, and if the tightening torque is high, the coils may simply become deformed. The size of the hole depends on two factors:

Countersinks are needed for chamfering when cutting internal threads.

1. The larger the diameter, the more the hole unfolds. For example, with D = 5 mm there is an increase of 0.08 mm, and with D = 10 mm there is already an increase of 0.12 mm.
2. Working conditions. The mechanic may be in an awkward position or at a height, this will cause increased hole breakdown, which will then affect the quality of the connection.

The problem is solved as follows: to make the internal thread full-profile, you must initially take a drill whose diameter is 0.1 mm less than the required one. It is possible that in some cases it will be difficult to rotate the tap, but usually no difficulties arise.

Preparation of tools

To perform internal thread cutting you will need:

• marking tools (tape measure, ruler, pencil);
• electric drill with a set of drills;
• countersink for chamfering;
• set of taps with hand crank;
• hammer;
• core

Drills should be threaded (sharpened) in accordance with the hardness of the material being processed. The harder it is, the greater the sharpening angle needs to be maintained. During drilling and cutting, the working parts of drills and taps must be lubricated. The choice of lubricant type depends on the viscosity of the steel. For regular and carbon steel, old lard or grease is suitable, for stainless steel - machine oil.

Marking of taps

Taps for cutting internal metric threads are marked with the letter “M”. In this case, the letter “M” is followed by the value of the diameter of the thread being cut. In addition to the diameter, the thread pitch is also indicated on the tool.

For example, the marking M4 × 1 means that the tool can make threads in a hole with a diameter of 4 mm in increments of 1 mm. In the case of a cutting tool for left-hand threads, the tool is marked LH.

The diameter and pitch of the thread are indicated in a manner similar to that described above.

Preparing to cut internal threads

In order for the process of cutting internal threads using a tap to not cause any particular difficulties and result in a high-quality result, it is necessary to properly prepare for this technological operation.

All methods of cutting threads using a tap assume that a hole with the appropriate diameter has already been made in the workpiece.

If the internal thread that needs to be cut has a standard size, then a special table with data in accordance with GOST can be used to determine the diameter of the preparation hole.

Table 1. Diameters of holes drilled for standard metric threads

If the thread that needs to be cut does not belong to the standard category, you can calculate the diameter of the hole to make it using a universal formula. First of all, it is necessary to study the marking of the tap, which must indicate the type of thread being cut, its diameter and pitch, measured in millimeters (for metric).

Then, to determine the cross-sectional size of the hole that needs 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 preparation hole is calculated as follows: 6 – 0.75 = 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 carry out the preparatory work.

Table 2. Diameters of holes drilled for inch threads

An important question to obtain a high-quality result is not only the question of what is used to cut the thread, but also what drill to use to make the preparation hole. When choosing a drill, you need 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 runout.

The sharpening angle of the cutting part is selected depending on the hardness of the material that needs 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°.

When drilling blind holes, control the drilling depth

How to cut threads correctly? First you need to select tools and consumables:

1. an electric drill or drilling machine capable of operating at low speeds;
2. a drill whose diameter is calculated or selected using reference tables;
3. a drill or countersink, with the help of 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 (drives);
6. bench vice (if the product in which the thread needs to be cut needs to be fixed);
7. core;
8. hammer;
9. machine oil or other composition, which during the processing process must be used to lubricate both the tap and the thread section being cut by it;
10. rags.

Diagram of thread cutting with a tap

How to cut a thread with a tap?

Tapping internal threads is a precise technological process that is carried out in a certain sequence.

Preparation

Initially, you need to prepare tools and additional devices for the work:

1. Small vice.
2. Electric drill with speed controller, metal drills.
3. Set of taps.
4. Metal brush.
5. Core with a hammer.

• Thread cutting with a tap is carried out manually at low speeds of the power tool.
• Tapping internal threads

Slicing process

Step-by-step thread cutting instructions:

1. Drill the hole with a core and a hammer.
2. Drill a hole with an electric drill. Hold the equipment exactly perpendicular to the surface being processed. Additionally, lubricate the drill with special oil.
3. Chamfer 1 mm in depth. To do this, use a drill of a larger diameter.
4. Secure the equipment in the collar. Perform two movements forward, one movement back. This way the metal shavings will come out of the hole and there will be no problems with cutting. Movements should be smooth.

During manual cutting, you must not apply pressure or continue to rotate the tool after it gets stuck. If it breaks, you need to drill out the tap using a drill or various metal drills. Another option for removing the fragment is to grind the area around the hole using a grinding machine. Then you need to remove it with pliers.

To create threaded connections, you need to buy the appropriate documents and learn how to work with them. By carrying out the work carefully, without haste, you can get a reliable connection in a short period of time.

Source: https://regionvtormet.ru/prochee/kak-narezat-rezbu-metchikom-vruchnuyu-pravilno-klassifikatsiya-instrumenta-i-osnovnye-rekomendatsii.html

Thread cutting. Tools, thread cutting methods

Threaded connections are very widely used in mechanical engineering, so the tool for making threads is one of the most common.

Threads are distinguished:

• according to the location of the turns - external and internal;
• in the direction of the helix - right and left;
• according to the shape of the groove profile - triangular, trapezoidal, rectangular, thrust and special;
• in the direction of the generatrix - cylindrical and conical;
• according to the size system - metric and inch.

Depending on the size of the thread, the type of production and the design of the parts, different types of thread-cutting tools are used:

• thread cutters (rod and shaped single-thread and multi-thread);
• taps (hand, machine, nut, machine, tool, master, etc.);
• round dies;
• threading heads;
• thread cutters.

1. Thread cutting tool

An axial multi-edged tool for forming and processing internal threads is called a tap, and external threads are called a die.

Hand taps are used for cutting internal threads.

The working part of the tap with length f is divided into cutting (taking) and guiding (calibrating) parts with lengths l1 and l2, respectively (Fig. 1, a). The cutters of the cutting part have main edges located on the conical surface and auxiliary edges that are part of the threaded profile (Fig. 1, b).

The guide part serves to guide the tap and self-feed by screwing in, and also serves as a reserve for regrinding. The cone angle of the cutting part depends on the angle φ, which is set equal to 5° for hand taps, 3°30′ for nut taps and 6°30′ for machine taps.

The guide part has a reverse taper to reduce friction and eliminate dangerous jamming of the tap in the hole.

Rice. 1. Structural elements (a), thread profile (b) and geometric parameters (c) of the tap

The length of the tap portion of the tap is taken to be 45 S for a rough tap, 2.55 S for a medium tap, and (1.5–2.0) S for a finishing tap, where S is the pitch of the thread being cut. Machine taps are made with a short taper equal to (1.5–2) S.

The rake angles of the taps are selected depending on the material being processed according to the following data:

• for soft steel γ = 12–15°;
• steel of medium hardness γ = 8–10°;
• hard steel γ = 5°;
• cast iron and bronze γ = 0–5°;
• light alloys γ = 25–30° (Fig. 1, c).

The tail part of the tap is designed to secure it in a driver or chuck and to transmit torque.

Hand taps are produced in sets. The kit includes three taps, which are divided according to their purpose into rough, medium and finishing. Chernovoy cuts the thread, removing up to 60% of the metal; the middle one gives more accurate threads, removing up to 30% of the metal; the third (finishing) tap performs final cutting and calibration of the thread, removing up to 10% of the metal.

For cutting pipe and small metric threads, use a set of two taps.

The taps included in the set differ from each other in thread profile and length of the intake part.

According to the design of the cutting part, two types of taps are distinguished - cylindrical and conical (Fig. 2; a, b).

Rice. 2. Formation of a cutting surface in a set of taps: a – cylindrical design, b – conical design

With a cylindrical tap design, all three tools in the set have different diameters. The finishing tap has a full thread profile. The diameter of the average tap is less than normal by 0.6 of the cutting depth, and the diameter of the rough tap is less than the thread diameter by the full cutting depth.

The length of the intake part, taking into account the distribution of thread cutting work between the three taps of the set, is set in the ratio 4:2:1. Thus, for a rough tap, the length of the intake part is 6–7 threads, for a medium tap – 3–3.5, and for a finishing tap – 1.5–2 threads.

The cylindrical design of the tap ensures that the tips of the teeth cut chips in the form of wide platforms.

With a tapered tap design, all three tools in the set have the same diameter and full thread profile with varying tap lengths.

The thread within the intake part is made conical and additionally cut along the tops of the teeth into a cone.

For conical taps, the cutting part is equal: for a rough tap - the entire length of the working part, for a medium tap - half of this length, for a finishing tap - two threads.

Tapered taps are usually used when cutting through holes. Blind holes are cut with cylindrical taps.

The rear (back) surface (Fig. 1, c) of the cutting teeth is backed up in a spiral, which allows maintaining a constant profile of the teeth after they have been sharpened.

Collars and clamps . Threading with hand taps is carried out using cranks that fit onto the square ends of the shanks.

The most common are simple double-sided knobs (Fig. 3).

Rice. 3. Double-sided driver: a, a1, a2 – holes for tap shanks

Universal gates (Fig. 4) are a frame 1 with two crackers - movable 3 and fixed 4, forming a square hole. One of the handles 2 ends with a screw for clamping the square of the tap.

Rice. 4. Universal driver: a – hole for the tap shank

Another version of the universal driver is shown in Fig. 5. This driver allows you to work with taps whose square sizes range from 5x5 to 25x25 mm.

Rice. 5. Universal wrench

Round dies are used for cutting fastening threads on bolts, screws and studs when working manually and on machines (revolving, automatic, etc.).

The round die on each tooth 2 (Fig. 6, a) has a rear 1 and front 5 surface, a back of the tooth 3 and a cutting edge 6 formed by a chip hole 4. The round die has a cutting and guide part with lengths l1 and l2, respectively (Fig. 6 , b). The length of the cutting part is equal to one and a half threads of thread, and the thickness of the die is seven to eight threads.

Rice. 6. Structural elements (a), main parts (b) and shapes of chip holes (c) of a round die

Rake angles are taken for hard materials being processed γ = 10–12°; for materials of medium hardness γ = 15–20°; for soft materials γ = 22–50°.

Dies are used (Fig. 7) solid (a), split (b) and sliding.

Rice. 7. Dies

When cutting manually, round and sliding dies are installed in special cranks and clamps.

The collars for round dies are made of a frame into the hole of which the die is placed (Fig. 8).

Rice. 8. Driver for a round die

The die is kept from turning by three locking screws (1, 2 and 3), the conical ends of which fit into recesses on the side surface of the die. The fourth screw fits into the slot of the adjustable die and secures the correct thread size.

The clamps for sliding dies (Fig. 9, a) are an oblique frame with two handles. In the central hole of the frame with dimensions A and C, sliding dies are installed and centered. Installation of the sliding dies to the required size is carried out using a pressure screw 1 acting on the movable part of the sliding dies.

Clusters for cutting threads on pipes differ from conventional ones in that four steel combs 2 fit into the slots of the clamp holder (Fig. 9, b).

Rice. 9. Dies: a – for sliding dies; b – for cutting threads on pipes

By turning the upper handle 1, you can bring the dies closer together or move apart, and thanks to this, use the same die for cutting threads on pipes of different diameters. The pipe die is equipped with guides 3, which are adjusted in the same way as the dies, by a lower handle 4. This ensures the correct position of the die on the pipe when cutting threads.

2. Technology and techniques for manual thread cutting

When cutting threads with taps and dies, part of the metal is not removed along with the chips, but is squeezed out along the cutting edges of the tool, forming a thread profile on the part. Taking this into account, the diameters of holes and threaded rods should not be made according to the nominal thread size, but slightly lower than it. For metric threads with a diameter of 6–10 mm, this difference is 0.1–0.2 mm; with a diameter of 11–18 mm – 0.12–0.24 mm; with a diameter of 20–30 mm – 0.14–0.28 mm.

The diameters of holes for the most common metric thread sizes are given in table. 1.

To form a thread entry at the end of the part, it is necessary to chamfer according to the height of the thread profile.

Table 1. Diameters of holes for cutting metric threads

Material	Metric thread diameter, mm
5	6	8	10	12	16	20	24
Steel and brass	4,2	5,0	6,7	8,4	10,1	13,8	17,3	20,7
Cast iron and bronze	4,1	4,9	6,6	8,3	10,0	13,7	17,1	20,5

A tap lubricated with grease is inserted into the drilled hole and, lightly pressing it against the part with the left hand, carefully turn the driver with the right hand until the tap grips the metal and its position in the hole becomes stable. After this, the knob is taken with both hands and rotated with the hands intercepted every half turn (Fig. 10, a).

Rice. 10. Movements when cutting threads: a – with a tap, b – with a die, c – with a die

After one to one and a half turns, the tap, shaking in a horizontal plane, is rotated in the opposite direction by about a quarter or half a turn. This is necessary so that the chips break and move out of the hole along the grooves of the tap without jamming the tap. Having finished cutting, pass it through or turn the knob in the opposite direction to unscrew the tap from the hole.

The second and third taps are lubricated with oil and inserted into the hole without a driver; Only after the tap is correctly installed on the thread, apply the driver and continue threading.

Thread cutting with dies should be done in the same way. Here, however, in addition to circular movements along arrow a (Fig. 10, b), the knob should also apply some downward pressure along arrow c. During the cutting process, it is necessary to ensure that the pressure on both handles is the same.

At the first stage of thread cutting, you should ensure the correct position of the tap and die in relation to the axes of the hole and the rod. The non-parallelism of the axes and their non-perpendicularity to the end of the part are controlled by a square and are eliminated by changing the position of the tool.

It is necessary to cut threads in small and blind holes of small diameter especially carefully, without overloading the tap and often clearing it of chips.

When cutting threads in deep holes, remove the tap from the hole for cleaning (2-3 times).

If it is necessary to obtain accurate and clean threads on rods, then cutting them should be done with roughing and finishing dies.

If thread cutting is performed with dies with sliding dies, then their compression (feed) should be done only at the beginning of the pass. After each pass along the entire length of the threaded rod, the die is driven in the opposite direction and then the dies are again tightened with a screw and the thread is again cut along the entire length of the rod to be cut until the desired thread diameter is obtained. You should not press the dies in the middle of the rod. Using sliding dies, threads are cut in several passes.

To cut pipe threads with a clamp, the pipe must be securely secured in a special pipe clamp (Fig. 10, c).

The cut end of the pipe is lubricated with oil (linseed oil), and then a die is installed at a length of no more than 2–3 threads, bringing the dies closer together so that the thread is cut to the full depth in 2–3 passes. For diameters up to 1” are limited to two passes; with diameters greater than 1”, a good thread can be obtained in only 3–4 passes. Before each repeated pass, the surface of the thread being cut and the thread of the dies must be thoroughly cleaned with a brush from chips and re-lubricated with oil.

The rotation of the clamp around the pipe is usually carried out with a rocking motion in four steps; For each step you need to turn the clamp 1/4 turn.

Threads up to 1½” in ​​diameter are cut by one mechanic; For large thread diameters, two people work together. When working in tandem, a full rotation of the die must also be done in four steps.

Source: https://extxe.com/19086/narezanie-rezby-instrumenty-sposoby-narezanija-rezby/

How to properly cut a thread with a tap: algorithm, recommendations, size tables

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

Manual cutting of internal threads is performed using metalworking taps complete with a wrench

Types and areas of application of taps

Internal thread cutting can be done manually or using various types of machines (drilling, lathe, 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 rotation, a distinction is made between machine-manual and machine taps, with the help of which internal threads are cut. Machine-hand taps equipped with a square shank are used in conjunction with a special device with two handles (this is the so-called tap holder). With the help of such a device, the tap is rotated and cuts the thread. Thread cutting with a machine tap is carried out on metal-cutting machines of various types, in the chuck of which such a tool is fixed.
2. Based on the method by which internal threads are cut, a distinction is made between universal (through) taps and complete taps. 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 that first begins to interact with the surface being processed performs rough processing, the second - intermediate, and the third, located closer to the shank - finishing. Cutting threads 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 of particularly hard material are processed, sets consisting of five tools can be used.
3. Based on the type of hole on the inner surface of which it is necessary to cut a thread, taps for through and blind holes are distinguished. A tool for processing through holes is characterized by an elongated conical tip (approach), which smoothly passes into the working part. Universal type taps most often have this design. The process of cutting internal threads in blind holes is carried out using taps, the conical tip of which is cut off and performs the function of a simple milling cutter. This design of the tap allows it to cut threads to the full depth of a blind hole. To cut a thread of this type, as a rule, a set of taps is used, driven manually using a wrench.
4. According to the design of the working part, taps can have 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. If threads need to be cut in parts made of very hard or viscous materials (stainless, heat-resistant steels, etc.), then for these purposes taps are used, the cutting elements of which are arranged in a checkerboard pattern.

A good tap is made of high-quality tool steel, looks neat and has smoothly machined turns and grooves

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

Features of the technology

When cutting internal threads 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 regular hammer. The drill is fixed in the chuck of an electric drill or drilling machine, on which low rotation speeds of the tool are set. Before starting drilling, the cutting part of the drill must be treated with a lubricating compound: a lubricated tool enters more easily into the structure of the material being processed 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 these purposes.
• If it is necessary to cut threads in small parts, they should first be fixed using a bench vice. When starting drilling, the tool fixed in the equipment chuck must be positioned strictly perpendicular to the surface of the workpiece. You should lubricate the tap regularly and ensure that it does not warp and moves strictly in the given direction.
• At the entrance to the hole, as mentioned above, it is necessary to remove the 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, installing them in the chuck of drilling equipment.
• The process of cutting internal threads begins with tap No. 1, which is the first to be installed in the driver. 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 being machined must be set at the very beginning of the work, since later, when the tool is already inside the hole, this will not be possible. When cutting a thread with a tap, you must adhere to the following rule: 2 turns of the tap are made in the direction of cutting the thread, 1 - against the direction. When the tap makes one revolution back, chips are thrown off its cutting part and the load on it is reduced. Thread cutting with a die is performed using a similar technique.
• After cutting the thread with tap No. 1, tool No. 2 is installed in the driver, and after it – No. 3. They are processed according to the method described above. When cutting threads with taps and dies, you need to feel when the tool begins to rotate with force. As soon as such a moment occurs, you should turn the knob in the opposite direction to throw the chips off the cutting part of the tool.

The harder the material being processed, the more abundantly the tap must be lubricated during the thread cutting process.

Before making internal threads with a tap or cutting threads with a die on external surfaces, you should thoroughly study these procedures and strictly follow the rules for their implementation. Only in this case can you count on the result satisfying you with its quality and accuracy.

Source: http://met-all.org/obrabotka/prochie/kak-narezat-rezbu-metchikom-tablitsa.html

How to cut a thread with a tap

The drilled hole in which the thread is cut with a tap must be machined or processed with a countersink. The diameter of the drill should be larger than the internal diameter of the thread, since when cutting a thread the material is slightly “squeezed out”. 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 thread, then the teeth of the tap will overheat due to high friction and build up metal due to the material squeezed out during cutting. As a result, 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.

We have already written how to choose a drill for tapping threads in another article.

2. Internal thread cutting

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

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

In order to facilitate the work, the driver with the tap is rotated not all the time in a clockwise direction, but one or two turns to the right and half a turn to the left, etc. Thanks to this reciprocal rotational movement of the tap, the chips break, they turn out short (crushed), and the process cutting becomes much easier.

Having finished cutting, turn the knob in the opposite direction to unscrew the tap from the hole, then drive it through.

Cutting fluids for thread cutting

Processed material	Lubricant
Carbon steel	Emulsion. Sulfurized oil
Structural steel	Sulfurized oil with kerosene
Tool steel	Mixed oils
Malleable cast iron	3-5% emulsion
Iron casting	B/o. 3-5% emulsion. Kerosene
Bronze	B/o. Mixed oils
Zinc	Emulsion
Brass	B/o. 3-5% emulsion
Copper	Emulsion. Mixed oils
Nickel	Emulsion
Aluminum and its alloys	B/o. Emulsion. Blended oils. Kerosene.
Stainless, heat-resistant alloys	50% sulphurized oil, 30% kerosene, 20% oleic acid (80% sulforesol, 20% oleic acid)
Fiberglass, vinyl plastic, plexiglass	3-5% emulsion
Textolite, getinaks	Blowing with compressed air

3. Rules for tapping threads

1. When cutting threads in deep holes, in soft and tough metals (copper, aluminum, bronze, etc.), the tap must be periodically unscrewed from the hole and the grooves must be cleared of chips;
2. Threads should be cut using a complete set of taps;
3. Cutting a thread immediately with a medium tap without a roughing pass and then a finishing one does not speed up, but, on the contrary, makes the work more difficult. In this case, the thread turns out to be of poor quality, and the tap may break. The middle and finishing taps are inserted into the hole without a driver, and only after the tap passes correctly along the thread, a driver is put on the head and threading continues;
4. The blind hole for the thread must be made to a depth slightly greater than the length of the part being cut, so that the working part of the tap extends slightly beyond the part being cut. If there is no such reserve, the thread will be incomplete;
5. During the cutting process, it is necessary to carefully ensure that there is no misalignment of the tap; To do this, every 2-3 cut threads you need to check the position of the tap in relation to the upper plane of the product using a square. Particular care must be taken when cutting threads in small and blind holes;
6. The quality of the thread and tool life are affected by the correct choice of cutting fluid.

Source: https://sverla.info/articles/kak-narezat-rezbu-metchikom/

How to cut a thread manually with a tap correctly: tool classification and basic recommendations

A variety of tools can be used for cutting threads, 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 and ease of use determined the widespread use of the hand tool in question. Let's take a closer look at how to properly cut a thread with a tap at home.

Lathes or drilling machines have been used for cutting threads for quite a long period. They are designed to rotate a workpiece or tool. In almost all cases, the working tool is a tap.

The classification of such a tool is carried out according to a number of different characteristics:

1. Depending on the method of driving them into rotation, they can be divided into machine or machine-hand taps. A special feature of the machine-manual variety of the tool is the presence of a square shank, which is suitable for a holder with two handles. Thanks to such a holder, you can rotate the tool and cut threads. As for the machine variety of the tool in question, it is installed in the chuck of various machines and can have a shank of various shapes and sizes.
2. There are universal and complete taps based on characteristics related to the specific application. The universal version has a working part, which is divided into several sections. They differ from each other in geometric shape, the first is intended for roughing, the second and subsequent ones are for bringing the surface to a suitable state. The complete version is designed for the phased use of several taps. As a rule, a set for cutting threads in ordinary metal is represented by three tools, and for processing hard alloys - five.
3. Taps are classified based on the type of hole being machined: blind or through. To work with through holes, a tool with an elongated conical tip is used, which is a continuation of the working part. Universal taps often have this type of shape. If you need to cut a thread in a blind hole, then use a tool that has a cut tip resembling a milling cutter. Due to this shape, it is possible to cut threads along the entire length of the hole.
4. Thread cutting tools are also classified according to the type of working surface. Examples include helical, straight or shortened grooves. On sale you can find a version that also has a combined surface. It is suitable for processing metals with low hardness. For hard alloys, a tool with cutting elements arranged in a checkerboard pattern is used.

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

Preparatory stage

To ensure that the work of obtaining threads does not cause many difficulties, careful preparation should be made for such a technological operation. All methods used related to cutting internal threads assume that a hole of the required diameter has already been obtained in advance. You can obtain the 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.

There is often a situation where it is necessary to obtain a thread of a non-standard size. In this case, the required hole diameter is calculated using a universal formula. Calculations are carried out as follows:

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

The easiest way to carry out the 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 runout during operation. When choosing a drill, it is worth remembering that it must have high-quality sharpening.

Experts recommend selecting the sharpening angle depending on the hardness of the material being processed.

As the hardness increases, the recommended sharpening angle also increases, but it should not exceed 140 degrees.

Manual tapping is only possible with the following tools:

1. An electric drill that can operate at low speeds.
2. A high-quality drill, the diameter and sharpening angle of which is selected from table values ​​or calculated.
3. To chamfer the edges of the hole, you will need a countersink or large diameter drill.
4. One or a whole set (depending on the type) of taps of the appropriate size.
5. A hand holder that is suitable for the tool used.
6. A bench vise in which the product will be fixed. When cutting a thread, a certain layer of metal is removed, which is only possible when a lot of force is applied. If the workpiece or finished product is poorly fixed, the quality of processing will be low.
7. Core and hammer.
8. In order to simplify the task, it is recommended to use machine oil to lubricate both the tool itself and the surface being processed. If you do not use machine oil or another substance with similar properties, the process may be significantly delayed.
9. Rags.

After finding everything you need, you can begin the actual work.

Features of the technology used

carry out the work in question with your own hands at home. To do this, you need to consider the recommendations below:

1. Before creating a hole, it is recommended to make a small recess, which will ensure the correct entry of the drill. You can use a core for this. When drilling through metal, it is recommended to set the drill speed to low, which will allow you to achieve high quality processing. Before drilling, you can treat the cutting edge with a special compound, which will make it easier for the tool to enter the metal.
2. At the time of creating the hole, the drill with the drill bit must be positioned strictly perpendicular to the surface being processed. When using the tap, the cutting edge should be constantly lubricated with engine oil, and you should also ensure that the tool is positioned strictly parallel to the axis of the hole created.
3. In almost all cases, chamfering is carried out at the entrance of the hole, the size of which is 0.5-1 mm. To do this, you can use a countersink or a larger diameter drill.
4. When using a set of taps, thread cutting should begin with tool No. 1. The direction of the thread should be strictly controlled at the very beginning of the work, since in the future it will be almost impossible to change the inclination of the tool used.
5. To obtain high-quality grooves, it is recommended to make two turns along the thread and one in the opposite direction. The reverse rotation is done in order to remove chips from the cutting edge, due to which the stroke becomes smoother.
6. After using tool No. 1, the second one is installed, and after a complete passage, the third one is installed. It is worth considering that with great force it is recommended to make one or several revolutions in the opposite direction, due to which the chips are removed from the cutting zone.

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

Source: https://tokar.guru/hochu-vse-znat/kak-pravilno-narezat-rezbu-metchikom-vruchnuyu.html

How to cut a thread. Internal and external thread cutting

Threaded connections are simple, reliable, and make it possible to adjust the tightening, as well as disassemble and assemble parts and mechanisms. They are widely used in various mechanisms, devices, and devices.

 Threads can be external (screw) or internal (nut). There are cylindrical triangular (sawtooth), conical triangular, rectangular, trapezoidal, thrust, and round threads. The most widely used is the cylindrical triangular or, as it is also called, fastening thread, figure No. 1.

Figure No. 1 – Thread elements on a bolt

1 - depth;

2 - top; 3 - step;

4 — depression;

5 - outer diameter;

6—inner diameter.

Internal thread cutting:

First of all, you need to choose the right drill bit for drilling the hole.

You should know that if you drill a hole for a thread with a diameter that exactly matches the internal diameter of the thread, then the metal squeezed out during cutting will put pressure on the teeth of the tap, which can cause the thread to end up with torn threads, and the tap may break.

If you drill a hole that is too large in diameter, the thread depth will be incomplete and the connection will be weak.
When drilling a blind hole for a thread, its depth must be made slightly larger than the part being cut, otherwise the thread will be incomplete in length.

Thread cutting is carried out in the following sequence: mark the drilling location with a center punch; secure the part in a vice; drill a hole; insert the tap into the hole (Figure 2) strictly vertically (along the square); put a crank on the tap, press it against the tap with your left hand, and turn it to the right with your right hand until the tap cuts into the metal on several threads and takes a stable position; take the knob by the handles with both hands and rotate it with the hands intercepted every 1-2 turns. Thread cutting is greatly facilitated if you use a tap to make 1-2 working turns to the right and 1-2 turns to the left; Having finished cutting, the tap is unscrewed from the hole, then once again driven along the resulting thread.

Figure No. 2 - Cutting internal threads with a tap:

a — installation of the tap in the hole;

b - thread cutting.

Rules for working with taps:

When cutting threads in deep holes, in soft and tough metals (copper, aluminum, bronze, etc.), the tap must be periodically unscrewed from the hole and the grooves must be cleared of chips; You need to cut a thread with a full set of taps - rough, medium and finishing.

The middle and finishing taps are inserted into the hole without a driver and only after the tap follows the thread correctly, a driver is put on the head and threading continues;
during the cutting process, you need to use a square to carefully ensure that there is no skew of the tap; The thread cutting area should be lubricated with oil.

External thread cutting:

At home, it is done with dies by hand.
The diameter of the rod for external threads should be 0.3-0.4 mm less than the outer diameter of the thread being cut. Deviations from this rule are not permitted.

Cutting an external thread with a round die is done in the following order:
a chamfer is removed at the upper end of the rod, which ensures that the die cuts into the metal;

The rod is clamped vertically in a vice so that its protruding end is 20-25 mm longer than the length of the part being cut (Figure No. 3); Place a die fixed in a knob on the rod and rotate it with slight pressure so that the die cuts into about 1-2 threads without distortion. After this, lubricate the rod with oil and smoothly rotate the knob 1-2 turns to the right and 1/2 turn to the left.

Thread cutting with sliding prismatic dies (Figure No. 3) is performed as follows: a chamfer is filed at the end of the rod; install dies into the die; clamp the rod in a vice; put the clamp on the rod and move the nuts tightly with a clamping screw; lubricate the dies and the rod with oil; The die is turned 1 - 1.5 turns clockwise, then 1-4, 1-2 turns back, and so on until the end of the thread; Having cut the thread, screw the die to the end of the rod, tighten the dies with a screw and pass the thread a second time; check the thread with a nut of the appropriate diameter; at the end of the work, the dies are removed from the die, cleaned of chips, wiped and lubricated with oil; wipe the clutch.

Figure No. 3 - Cutting threads using a die

a — Cutting threads with a round die
b — Cutting threads with prismatic dies

Source: https://bip-mip.com/narezanie-rezby.html

How to cut a thread with a tap or die. Learning a specialized tool

Currently, it is difficult to imagine carrying out metalwork work without a special thread-cutting tool.

This tool can cut threads on products made of non-ferrous metals and steel.

Taps

The internal threads on the parts are cut using taps.

Taps for cutting inch and metric threads are usually manufactured in sets of two.

Taps for inch threads (less than 2 inches) and for metric threads from 32 to 54 mm with a pitch of more than 3 mm are manufactured in sets of three pieces. Such sets include the first (rough), second (medium) and third (finishing).

There is one circular mark on the tail of the first tap, two on the tail of the second, and three on the tail of the third.

The thread size is also indicated on the tail of the tap.

When cutting threads by hand, a special driver is used for the tap.

More details about video tags at the end of the article.

How to cut a thread with a tap

At first glance, cutting a thread with a tap looks simple, but this does not mean that it will be easy the first time. Pay special attention to choosing a quality tool. A dull tap has every chance of breaking. Getting the fragment out of the hole is still a hassle.

When cutting threads, follow the rule: 1 - 2 turns forward (cutting threads) - 0.5 - 1 turn back.

When cutting threads in blind holes, chips will inevitably accumulate; it is necessary to unscrew the tap and remove metal waste from the hole and from the tap.

If the tap has been removed completely, be careful when screwing it in again or when passing the next number. It is necessary to hit the already cut thread and not cut it.

The diameter of the drilled hole must correspond to the diameter of the thread (Table 1):

Thread diameter	Hole diameter	Thread diameter	Hole diameter
1	0,75	2,6	2,15
1,2	0,95	3	2,5
1,4	1,15	3,5	3
1,7	1,35	4	3,3
2	1,6	5	4,1
2,3	1,9	6	4,9
2,5	2	8	6,7

Deviations from the specified values ​​will lead to poor-quality threads.

And of course, don’t forget about lubricants (oil, kerosene, grease, etc.).

Dies

External threads are cut using dies.

The dies are produced as sliding (prismatic), rolling and round. Round lerks are divided into cut and solid.

Solid round blades are used for cutting metric threads on parts with a diameter from one to 76 millimeters. For cutting inch threads, dies with a diameter of 1/4 to 2 inches are used.

When manually cutting threads, the dies are clamped into a specially designed driver called a handle holder.

It is necessary to use lubricating fluids and comply with the dimensions in Table 2:

Thread diameter	Rod diameter	Thread diameter	Rod diameter
1	0,98	2,6	2,54
1,2	1,17	3	2,94
1,4	1,37	3,3	3,23
1,7	1,66	4	3,92
2	1,96	5	4,89
2,3	2,25	6	5,86
2,5	2,45	8	7,83

The process of cutting external threads is clearly presented in the video:

Pay attention to the reverse rotations (opposite to the main working stroke of the tool).

Special dies and taps

Special dies and taps are tools that are manufactured with various deviations from DIN, ISO, ANSI and other standards. Changes may affect the degree of accuracy, the length and shape of the shank, the number of threads per inch, thread pitch, diameter of the thread being cut and other parameters.

Standard tools and taps are made from HSS grade high-speed steel, as well as from improved high-speed steel with the addition of vanadium and cobalt grade HSS-E. Various wear-resistant coatings are also applied to special taps.

Thread gauge

To control the profile shape, diameter and thread pitch, special and universal tools are used.

A thread gauge is used to check the thread profile.

For precise control, special microscopes are sometimes used. The diameter of the thread can also be measured with a caliper.

Source: http://bydom.ru/news/read/kak-narezat-rezbu-metchikom-ili-plashkoj.html