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Details Category: Long products

Internal thread cutting

Internal threads (threads in a hole) are cut tap(picture on the right). Taps are made from tool carbon, alloy or high-speed steel. The tap consists of shank And working part .

Shank the tap is attached to collar or machine chuck.

Working part A tap is a screw with longitudinal or helical grooves for cutting threads. As with dies, the working part of the tap has a chamfer to facilitate the entry of the tool into the hole. Helical grooves, similar to longitudinal holes in the die, form cutting edges. The shavings go down them.
Hand taps for cutting metric threads are produced in a set that includes two taps for threads with a diameter of up to 3 mm and three ( № 1 -rough , № 2 - average And № 3 - finishing ) for threads with a diameter greater than 3 mm. Rough tap performs the main work and cuts off up to 60% of the metal layer to be removed. Medium tap cuts off up to 30% of the metal layer. Finishing tap gives the thread its final shape and dimensions and cuts off the remaining 10% of the metal layer. The taps included in the kit have different diameters of the thread-cutting part and different shape profiles. Circular marks are stamped on the tail of all the taps in the kit ( 1,2,3 ) or tap numbers are indicated, and thread sizes are indicated - diameter And step.

To rotate the tap when cutting threads manually use the device - knob(picture on the left). There are collars - unregulated(rice. A) And adjustable(rice. b).

Before you start cutting threads in the hole, mark the location of the hole and make sure it is by piercing. Taking into account the dimensions of the future thread according to the table (see table below), the diameter of the drill is selected.

Thread diameter	Drill diameter		Thread diameter	Drill diameter
	Cast iron	Steel		Cast iron	Steel
2	1,6	1,5	3,0	4,1	4,2
2,3	1,9	1,9	6,0	4,9	5,0
2,6	2,15	2,15	8,0	6,6	6,7
3,0	2,5	2,5	10,0	8,3	8,4
4,0	3,4	3,5	12,0	10,0	10,1

Sometimes you can use in a simple way- to find out the diameter of the hole for the desired thread, subtract the pitch from the thread diameter and get the hole diameter.

The diameter of the threaded hole can be calculated using the formula D=d-1.6t,
where D is the hole diameter, mm;
d - diameter of the thread being cut, mm; t - thread depth, mm.

The dimensions of the driver for securing the tap when cutting threads are selected depending on the diameter of the thread being cut. The approximate length of the knob can be determined by the formula
L=20D+100 mm,
where D is the thread diameter.

When cutting an internal thread, the metal is squeezed out, reducing the diameter of the hole. Therefore, the diameter of the drill should be slightly larger than the internal diameter and smaller than the external diameter of the thread. If the hole diameter is smaller than required, the tap will break, and if it is larger, the thread will be incomplete and weakened.
The drilled hole is processed countersink. The use of this tool allows you to improve the quality, reduce the taper, and the ovality of the side surface of the hole. A countersink works in the same way as a drill.

For high-quality thread cutting, it is important to correctly secure the part in a vice and install the first tap in the hole (Fig. above A). The part is fixed so that the surface with the hole is parallel to the planes of the vice jaws, and the tap is perpendicular to the plane of the part and the jaws. Perpendicularity (angle 90°) is checked with a square (Fig. b).
Cut the thread as follows (Fig. V). First, install tap No. 1. First, its threaded part is lubricated with oil. Pressing the crank against the tap with your left hand, smoothly rotate it to the right with your right hand until the tap cuts into 1-2 threads. At the same time, they monitor the conservation right angle, guiding the tap if necessary. After the tap has taken the correct stable position and threading has begun, the driver is taken with both hands and rotated with light pressure, intercepting every half turn. In order for the chips to break and go into the grooves of the tap, it is rotated back and forth: one and a half turns forward and half a turn back.
Having completed the passage with tap No. 1, it is unscrewed, tap No. 2 is inserted, tucked into the thread, a knob is installed and cut. The thread is finally finished using tap No. 3 and the thread is checked (Fig. d).
Blind holes for threads are drilled to a depth slightly greater than the length of the thread.
The quality of the thread can be checked in a workshop by screwing the appropriate bolt into the hole.

When cutting threads, the following defects sometimes occur and should be avoided:
1) rough or torn cuts- this happens if there is no lubrication, as well as due to a misalignment of the tap or die;
2) partial profile thread- if the hole diameter is larger than normal or the diameter of the rod less than normal;
3) thread distortion or tap breakage- if the diameter of the hole is less than the norm or the diameter of the rod is more than the norm.

When cutting threads in tough and soft metals, it is necessary to periodically unscrew the tap and clean the grooves from chips.
Threads should be cut sequentially using a complete set of taps.
Care must be taken to ensure that the tap is not skewed.
Particular care must be taken when cutting threads in blind holes.
Be sure to periodically lubricate the thread being cut with oil.

A threaded connection is the main method of connecting parts. When making any metal device with your own hands, the need arises to cut threads yourself. Tapping allows you to create threads in various holes with your own hands.

In practice, we have to deal with various materials that differ in their properties. Cutting should take into account the characteristics of the material. There are certain rules, developed over the years, that allow you to perform quality thread cutting different sizes and types.

Features of the structure of taps

A tap belonging to the group of metalworking and turning tools cutting tools, has the shape of a rod on which the cutting element is made. It is intended for cutting internal threads, that is, inside the hole in various materials, as well as for restoring damaged internal threads.

Kit metal cutting tools: a - drills, b - countersinks, c - reamers, d - taps, d - dies.

The tools consist of a working and a tail part. In turn, the working part is divided into an intake (cutting) and calibrating section. The cutting section is responsible for the main function of the tap - cutting threads, and, most often, has cone shape. It has teeth in the form of incisors placed around a circle. The calibrating section performs the task of final formation. It is made in the form of a cylinder with teeth that are a continuation of the teeth of the cutting section. This section is much longer than the fence. The working part is cut in the longitudinal direction with grooves, which are designed to form cutters and remove chips. Taps with a diameter of up to 22 mm have three grooves. Devices special purpose can be manufactured without grooves. The grooves can be straight or helical.

The tail part has the shape of a cylinder. At the end of the section there is a square for installation in the fastening tool. In this part the diameter marking is stamped out. Using a shank, the tool is fixed in a hand holder or machine chuck.

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Main types of taps

According to the method of use, taps are divided into two types - manual and machine. The first ones are installed in manual holders (knobs) and are designed for cutting internal threads manually. Machine ones are mounted in special holders for lathe chucks.

Based on the type of thread cut with a tap, they are divided into several types. Metric is designed for cutting the most common metric threads. Pipe forms internal threads on pipes, as well as reinforced threads in holes metal parts. Inch is a device for special inch threads, as well as cone-shaped ones. Specialized nut taps are made of very strong steel (R6M5) and have a special shank shape.

In addition, taps are divided into single and complete. Complete ones are used to cut in several passes. The set may contain two taps - finishing and rough; or three taps - roughing, medium finishing and finishing. Completeness is indicated on the tail of the instrument. The taps included in the set differ in the shape of the tooth: the roughing one has a trapezoidal tooth; the middle one has a triangle with a rounded top; the finishing one has a triangle with a sharp apex.

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Main settings

In general, cutting a thread means making a protrusion on inner surface holes so that it forms a helix. Such a protrusion, like all threads, is characterized by the following basic parameters: the helix angle, pitch, type of protrusion profile and profile elevation angle, outer and inner diameter. In addition, it is customary to distinguish another depth, determined by the outer and inner diameters.

In direction, the thread can be right-handed, when the helical protrusion rises counterclockwise, and left-handed, when the direction of rise of the protrusion coincides with the clockwise movement. Based on the shape of the protrusion profile, there are two main types: threads with a rectangular profile and with a triangular profile. There are also special profile forms, but they are living conditions are practically not used.

The main thread is metric. This profile is a triangle with a profile angle of 60º. According to the pitch, metric is divided into threads with a large pitch and with a fine pitch. An example of the full designation of a metric thread is M10x1-6N. The designation should be understood as follows:

• M - metric thread;
• 10 - nominal diameter;
• 1 - thread pitch;
• 6H - tolerance limits for dimensional deviations.

With a normal (large step) the designation is abbreviated (for example, M10). In the case of a left-hand thread, the designation LH is entered.

The second most common type in everyday life is the cylindrical pipe type. The profile is a triangle with an apex angle of 55º. This type is used when connecting pipes and cylinders, where increased tightness of the connection is required. Straight pipe threads are designated by the letter G, indicating the diameter in inches.

The thrust thread is based on a trapezoidal profile with inclination angles of 3º on one side and 30º on the other. The designation includes the letter S, diameter and pitch.

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Choosing the right tap

First, the type of tap is selected based on the type of thread and its purpose (profile shape, thread pitch, tolerances). According to the accuracy requirements (class), it is determined whether a single tap should be used or a set is required. In addition, taps are produced with different finishes of their cutting element, which affects the accuracy of cutting the thread profile.

The material in which the thread must be cut influences the choice of tap. So, you should take into account the front angle of sharpening the teeth. It is for steel - 5-10º, for copper alloys - 0-5º, for aluminum and alloys - 25-30º. Devices can be made from ordinary steels, high-strength steels or high-strength brazed steels, which must be taken into account when considering what strength of material is being processed.

The main choice is made based on the diameter of the hole in which the internal thread is cut. The diameter of the tap should be slightly smaller than the diameter of the hole. So, for a metric M20 thread (tap diameter 20 mm), the hole diameter is 19 mm. With metric thread, if not special requirements, then the standard step is executed. For example, M4 thread - pitch 0.7 mm; M5 - 0.8 mm; M10 - 1.5 mm; M12 - 1.75 mm, etc.

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Fastening tool

In order to ensure thread cutting, the tap must be given a rotational movement with the application of force. This function is performed by a manual holder - a knob. It provides vertical mount tool and the ability to apply significant loads using levers. Standard design The driver contains a tap fastening unit and elongated handles, with which you can rotate the device manually with force.

The device is mounted in two ways. One of the knob designs consists of two parts. When these parts are joined, a hole is formed inside for installing the tap. Both parts come together at an adjustable distance, which is set with screws. The second option provides a single knob design with a hole in the center. The tap is inserted into this hole and clamped with 3-4 locking screws. The handles of the knob are made on both sides. Handle lengths can be 15-25 cm.

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Preparing for slicing

Cutting internal threads begins with drilling the desired hole - through or blind. The main condition: the hole must be smaller than the thread diameter. When drilling a hole, it is recommended to select a drill from the following condition:

• for M3 thread - drill diameter 2.5 mm;
• at M4 - 3.4 mm;
• at M5 - 4.2 mm;
• at M6 - 5 mm;
• at M8 - 6.7 mm;
• at M10 - 8.4 mm.

If it is necessary to cut a large thread, the hole diameter is determined by approximately multiplying the thread diameter by 0.8.

The hole for cutting internal threads is made on drilling machine or an electric drill. In the latter case, the workpiece is clamped in a vice. It is necessary to ensure that the drill is directed strictly vertically. The top edge of the hole is chamfered to facilitate entry of the tap. It can be done with a larger diameter drill or file. After drilling, the hole is thoroughly cleaned of chips, which is especially important for blind holes.

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Tapping threads

The part in which the hole for the internal thread is drilled is secured in a vice so that the chamfer on the hole is at the top. The axis of the hole should be strictly perpendicular to the table. The tap is securely fixed in the driver socket and inserted vertically into the chamfer of the workpiece hole. Holding the handles of the driver with both hands, the tap is pressed against the part and rotated clockwise. Rotation is smooth and even with light pressure. This is done two times forward. Then turn it half a turn back (counterclockwise). The entire hole is drilled in this sequence.

When cutting threads, the bolt must be secured.

When cutting threads, it is necessary to periodically cool the tool. It is recommended to use the following substances: when working with aluminum and its alloys - kerosene, with copper - turpentine, with steel parts - emulsion. For metals such as bronze or cast iron, cooling lubricants may not be used.

It is best to use complete taps for cutting internal threads with a tap. First, the rough thread is cut. Then the middle tap is passed in the same way, and only then the thread is finally formed using a finishing tap. Excluding any tap from the process will not significantly speed up the process, but will significantly degrade the quality of work.

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. Most wide application received a 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 - internal 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 external thread with a round die is made in this order:
at the upper end of the rod, a chamfer is removed, 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.

Tapping internal threads begins with choosing the right tool. Then the first step is to drill the hole. In fact, this stage is the most important, since if you make a mistake with the selection of the diameter, then either the bolt will hang loose, or the tap will break due to overload when cutting a thread. It is best to determine the hole diameter using tables, but you can also make a rough estimate: by subtracting its pitch from the thread diameter, you can get an approximate value of the required hole diameter.

For example, if the outer diameter of the thread is 18 mm and the pitch is 1 mm, then you need to drill a hole of 17 mm. It is necessary to drill strictly perpendicular to the surface of the part (due to deviations, defects in cutting are possible). It is advisable to make a small chamfer at the drilled hole. For blind holes, the depth must be greater than the length of the part being cut so that the tool, when cutting, goes beyond the required thread length. If this margin is not provided, the thread will be incomplete.

Detail with drilled hole secured in a vice. The tap is fixed in the driver (if not available, use an adjustable wrench) or in the machine chuck. The quality of the thread, cutting speed and tool life are significantly influenced by the correct selection of cutting fluid (coolant). In order not to damage the tool, and to obtain a clean thread with the correct profile, it is necessary to use the following coolant:

diluted emulsion (one part emulsion mixed with 160 parts water);

for parts made of brass and steel, you can use linseed oil;

For aluminum products– kerosene;

for parts made of red copper - you can use turpentine;

In products made of cast iron and bronze, cutting should be carried out dry.

Mineral and machine oils should not be used - they contribute to a significant increase in the resistance that the tool overcomes during operation, have a negative effect on the roughness of the thread and lead to rapid wear of the tap.

1.2. Rules for cutting internal threads with a tap

When manually cutting threads, the tool is inserted into the hole vertically (without distortion). The driver is not rotated in the desired direction (clockwise for right-hand threads) all the time, but is periodically made 1-2 turns in the opposite direction.

With such a rotational-return movement of the tap, the cut chips break, become short (crushed) and are easier to remove from working area, and the process of thread formation is greatly facilitated. After cutting is completed, the tool is turned out by turning the knob in the opposite direction, then it is driven along the finished thread through or until it stops for blind holes. You must also adhere to the following rules:

When forming threads in tough and soft metals (aluminum, copper, babbitts and others), as well as in deep holes, the tool should be periodically unscrewed from the hole to clean the grooves from chips.

When using a tap kit, all tools in the kit must be used. Cutting immediately with a finishing tap or a medium one, and then finishing without a roughing pass does not speed up, but only slows down and complicates the cutting process. In addition, the thread turns out to be of poor quality, and the tool may break. The finishing and middle taps are screwed into the hole by hand (without a driver) until the tool follows the thread correctly, and only after that the driver is installed and work continues.

During the cutting process, it is necessary to carefully monitor the correct insertion of the tool so that it does not become distorted. To do this, it is necessary to check the position of the tap relative to the upper plane of the part using a square after every newly cut 2-3 threads of chips. Particular care should be taken when working with blind and small holes.

Tap design

Tap(Fig. 1) is a hardened screw on which several straight or helical grooves are cut, forming the cutting edges of the tool. The grooves also provide accommodation for chips generated during cutting; chips can be removed from the cutting zone.

The tap consists of two parts- a working shaft and a shank, at the end of which there is a square (for hand taps). The working part of the tap includes: a cutting (taking) part, which ensures the removal of the main part of the processing allowance; a calibrating part that performs final processing of the thread; chip flutes; feathers (thread turns separated by chip grooves) and a core, which provides the tap with sufficient strength and rigidity for processing. The tail part of the tap serves to secure it in the driver, which is used to carry out working and idle movements of the tap.

The working part of the tap is made from tool carbon steels of grades U11, U11A, high-speed steel or hard alloy. The choice of material for the working part depends on the physical and mechanical properties of the workpiece being processed. For solid taps, the material of the tail part is the same, but for taps consisting of two parts connected by welding, the tail part is made of structural steel grades 45 and 40X: The number of chip grooves made on the tap depends on its diameter (three grooves for taps with a diameter up to 20 mm and four - for taps with a diameter over 20 mm).

The main work when cutting threads is performed by the cutting edges formed by the intersection of the front surfaces of the groove with the rear (backed, made in an Archimedean spiral) surfaces of the working part. Relieving the back surface of the cutting teeth allows them to maintain a constant profile after regrinding, which is carried out centrally in sharpening shops.

As a rule, taps are made with straight flutes, but to improve cutting conditions and obtain accurate and clean threads, taps with helical grooves are used. The angle of inclination of such a groove to the axis of the tap is 8... 15°. To obtain precise and clean threaded surfaces in through holes When processing soft and viscous materials, grooveless taps are used.

Rice. 1 Tap:

a – design: 1 – thread (turn); 2 – square; 3 – tail; 4 – groove; 5 – cutting feather; b – geometric parameters: 1 – front surface; 2 – cutting edge; 3 – backed surface; 4 – back surface; 5 – cutting feather; α – clearance angle; β – cutting angle;δ – sharpening angle;γ – front angle; c – with a helical flute: 1 – groove; g - cutting blind threads; ω – angle of inclination of the helical groove.

We can talk for a very long time about how to cut threads correctly. Entire books and monographs are devoted to this. But, the vast majority of threads used do not require special cutting skills, and we will focus our attention on the basic methods.

Internal threading

To cut internal threads, taps are used - tools like a screw with cutting grooves. Typically, cutting requires two taps for rough and finishing passes. The difference is in the depth of cutting the grooves. There are also three-pass taps and other cutting options. To work with them, special wrenches are required, which can be different in design, but must be suitable in size for the working tool.

Before cutting a thread, it is very important to prepare a hole of the required diameter. Otherwise, you will either break the tap (with a hole diameter less than required) or get a poor-quality thread. So, if an M10 internal thread is required, i.e. 10 mm in groove diameter, then the hole diameter should be 8.5 mm. This is determined based on the thread pitch. For M10 it is 1.5 mm and, accordingly, the required hole diameter will be 10-1.5 = 8.5 mm. Thread pitches can be found using special formulas, although more simple option will not calculate the diameter, but find out its value from the table.

After preparing the hole, we proceed directly to considering the issue of how to properly cut the thread. We attach the tap to the holder and slowly begin to screw it into the hole, paying special attention to maintaining the accuracy of the direction. Cutting is done clockwise with the application of certain forces.

For successful cutting, the tap must be sharp and of high quality. The duration of its operation and the likelihood of breakdown depend on the use of lubricant. A few drops of oil will not only make cutting easier, but will also improve the quality of the carving. This is especially important for cutting blind holes. Naturally, it doesn’t hurt to have certain skills that come with practice. However, this operation is relatively simple and skills are acquired after 3-4 threads.

How to properly cut threads on a bolt or stud

Bolts, studs and other similar fasteners have an external thread and, accordingly, you will need a die (die) or die. The first ones are used for metric threads, clamps - for pipes. Cutting with clamps is a little easier - they have special pipe fittings (put them on and start cutting) and ratchet holders. To work with a die, it is very important to make the first turns evenly, so it is strongly recommended to first make a small chamfer with a file.

Unlike internal threads, there are no difficulties with diameters. So, for an M10 thread you will need a workpiece with a diameter of 10 mm. The basic rules of cutting differ little from working with a tap. The dies must be sharp and of high quality, and lubricant must be used when cutting. Sometimes it is more difficult to start carving and if a distortion is noticeable, then it is necessary to cut off the defective section and start again. For any type of thread, the workpiece must be tightly secured in a vice.

Finally…

In conclusion, I would like to warn you that there is another formula for determining the diameter of a hole for an internal thread - tap diameter x 0.8. But it is only relevant for manual three-pass taps. For all other cases, it is better to use the appropriate tables.

And, of course, the success of cutting and the quality of the carving largely depend on the quality of the tool itself. However, this problem can be easily solved - after all, in the Mecca of Tools online store you will find any tool you need at an attractive price.

Table 1. Recommended diameters of rods for threads cut with dies

Thread diameter in mm	M 6	M 8	M 10	M 12	M 14	M 16	M 18	M 20
Rod diameter in mm	5,8	7,8	9,8	11,8	13,7	15,7	17,7	19,8

Table 2. Hole diameters for metric threads.

Designation	holes, mm
M1.0	0,75
M1,2	0,95
M1.4	1,1
M1.7	1,35
M2.0	1,6
M2,3	1,9
M2.6	2,15
M3x0.5	2,5
M3.5	2,9
M4x0.7	3,3
M5x0.8	4,2
M6x1	4,96
M7	6,0
M8	6,7
M9	7,7
M10x1.5	8,45
M11	9,4
M12x1.75	10,18
M14	11,8
M16	13,8
M18	15,3
M20	17,3

Table 3. Hole diameters for inch threads.

Thread designation, inch	Nar. diameter, mm	Thread pitch		Hole diameter, mm
		Threads per inch	mm
1/8"	2,095	24	1,058	0,74
3/16"	4,762	24	1,058	3,41
1/4"	6,350	29	1,270	4,72
5/16"	7,938	18	1,411	6,13
3/8"	9,525	16	1,588	7,49
7/16"	11,112	14	1,814	8,79

Table 4. Pipe inch threads.

Designation	Outer diameter, mm		Thread pitch		Interior holes.mm
	pipes	threads	threads per inch	mm
pipes 1/4"	13,5	13,158	19	1,337	11,8
pipes 3/8"	17,0	16,663	19	1,337	15,2
pipes 1/2"	21,25	20,956	14	1,814	18,9
pipes 3/4"	26,75	26,442	14	1.814	24,3
pipes 1"	33,5	33.250	11	2,399	30,5