The dimensions and the table of values \u200b\u200bof the metric thread allows you to perform high-quality cutting without resorting to complex mathematical calculations. The table provides the necessary information regarding the diameter of the holes, the applied pitch, drill, etc. All parameters are standardized, which allows you to get a high-quality and reliable threaded connection with your own hands.

Photo metric thread table

• The vast majority of fasteners are based on metric threads in our country;
• The angle of the triangular profile of the metric thread is 60 degrees;
• All dimensions are in millimeters;
• Metric cutting is divided into products with large and small steps;
• A large pitch is relevant for diameters of 1-68 mm, and a small pitch - for diameters of 1-600 mm;
• Large-scale cutting is used in joints that are subjected to shock loads;
• Fine-threading is relevant for thin-walled parts and for imparting tightness to joints;
• Small-thread cutting has become widespread in installation and adjustment fasteners. This is due to the fact that with their help it is easy to adjust the parameters with high accuracy;
• All modern machines are designed using only metric cuts.

Characteristics and designations

Photo of the table of the main sizes

There is metric, inch, pipe cutting. Each of them is classified according to several criteria:

• The direction of the turns is left and right;
• Profile shape - round, persistent, triangular, etc .;
• Location - external, internal;
• The nature of the surface and function - inch, metric, conical, etc .;
• The number of entries is single-entry and multi-entry.

At the same time, inch and pipe cutting is not as common as metric. In this regard, leaving inch and pipe threads, and consider metric in more detail.

Thread has two main characteristics.

1. Nominal diameter They are called the conventional dimensions used in the notation. The nominal diameter is equal to the outer diameter of the nut and bolt, which are equal to each other.
2. Thread pitch. The dimensions of the thread pitch equals the distance between two identical points of the nearest profiles, which are located in the same plane. The definition is quite complicated, but in practice, finding these sizes is very simple. To determine the dimensions, you need to roll a bolt on a sheet of high-density paper at its core and measure what step is between the nearest grooves located. This is a step. To determine such dimensions in this way is not a high-precision method. But to make sure that the dimensions are calculated correctly, there is a special table. This table allows you to check with your calculations, or determine the required parameters without resorting to measurements or mathematical calculations.

Inch, pipe and our metric cuts have certain designations of sizes and other parameters. So that the table does not cause a lot of unnecessary questions, we will try to talk about all the nuances of the notation presented in it.

Letters and numbers are used to indicate threads. As an example, M40 thread. Here:

• The letter M means the type of cut. M is metric. She's not an inch, a pipe. Everything is very clear here;
• 40 are nominal diameters. The number after the letter indicates what nominal diameters the thread is characterized. In our case, it is 40 mm;
• If the thread pitch is large, this is not displayed in the designation. It can be determined according to GOST.

As an alternative, consider an example with a small step - M30x2.

• Here the situation is similar in diameters - this figure is 30;
• Metric cutting, as the letter M tells us;
• 2 means the pitch is 2 millimeters.

And a couple of important points.

1. A thread can have different steps and can be left-handed or right-handed.
2. Right-hand thread in the designations is not indicated.
3. If you see something like the M20 LH, this indicates the left-hand direction of the thread.
4. The number of visits. For a single-thread, the number is not indicated, since it is always 1. If it is a multi-thread, then the designation looks something like this - M30x3 (P2). Here, in parentheses indicate the thread pitch, and 2 is the number of entries.

Tap selection

The tap is the main working tool with which the internal cutting of future threaded connections. Because to make different kinds   threads with a certain step, you will need to correctly select a tap to complete the tasks.

• First of all, the master should choose the type of tap that is suitable for the planned thread. In our case, we are talking about taps for metric cutting;
• Next, the purpose is determined - step, tolerances, profile form;
• Depending on the accuracy class, the master decides whether it is possible to do with a single tap, or to complete the operation you need to get a kit - a draft and final tap;
• The material on which the cutting is performed. The main material where the thread is made is metal. Moreover, it can be different in terms of strength, which directly determines the choice of tap characteristics;
• The front angle of sharpening the teeth. For each type of metal there is a certain value. If it is steel, the angle is from 5 to 10 degrees, for copper - from 0 to 5 degrees, and in the case of aluminum - from 25 to 30 degrees;
• Taps can be made from ordinary, high strength steel   or from ordinary metal, but with solders of increased strength. The latter option allows you to reduce the cost of the production of taps, but maintain their high reliability;
• The key to choosing a tap is the diameter of the hole. It is on it that the cutting of the internal thread will be carried out;
• In this case, the diameter of the tool must be slightly smaller than the diameter of the hole. If you require a metric type of thread type M20, that is, the diameter of the tap is 20 mm, then the diameter of the hole will be 19 mm. All required parameters are determined by a special standardized table;
• If the thread does not have special requirements, the standard step specified in the table is applied.

Nuances of slicing

When the diameters and other parameters of the required thread are determined and the tap itself selected, a cutting operation should be performed.

1. The workpiece on which the cutting is performed is fixed in a vice.
2. The axis of the hole should be positioned as perpendicularly as possible relative to the desktop.
3. The tap is installed in the socket of the collar, in a vertical position it starts into the chamfer under the hole in the workpiece.
4. With two hands, the master holds the knob, pressing the tap to the part and rotating clockwise.
5. The tool should be rotated gently, smoothly and evenly, with a little pressure.
6. Two full turns are made, after which a half turn is made backwards, counterclockwise.
7. In the process of manufacturing the thread, the tool is necessarily cooled. If it is aluminum, kerosene is used, turpentine acts as a cooler for copper, and an emulsion for steel products. Cast iron and bronze do not need cooling.
8. The internal thread is carried out by a set of taps.
9. First, a rough tool is used, then the middle one, and the finishing work finishes. Excluding one of the taps, you will not speed up the cutting process, but the thread itself will turn out to be much worse in quality.

Run metric cut   not difficult if you use the appropriate tools and rely on the standardized parameters of specialized tables.

Table of diameters of threaded holes

Thread   represents a helical groove of constant cross-section, made on the external (external thread) and internal (internal thread) cylindrical or conical surface. It is used to connect parts, as well as to convert rotational motion to translational or vice versa, in mechanisms and machines.

Thread   there are single-run, formed by one helix (thread), or multi-run, formed by two or more lines.

In the direction of the helix thread   subdivided into right and left.

Depending on size system thread   there are metric, inch, pipe.

In metric carving   the angle of the triangular profile is 60 °, the outer, middle and inner diameters and pitch thread   expressed in millimeters. Metric threads with a large pitch are indicated by a letter and a number expressing the outer diameter in millimeters: M10, M16, and so on. To indicate thread   with a small step (the distance between the turns), a number expressing the step is added to this data thread   in millimeters: M6 × 0.6, M20 × 1.5 and the like.

In inch carving   the angle of the triangular profile is 55 °, the diameter of the thread is expressed in inches (1 inch \u003d 2.54 cm), and the pitch is the number of threads per inch.
Designation example: 1 1/4 ″ (outer diameter thread   in inches).

Pipe thread   differs from the inch in that its initial size is not the outer diameter, but the diameter of the pipe hole, on the outer surface of which is cut thread.

Designation example: 3/4 ″ pipe. (numbers indicate the inner diameter of the pipe in inches).

Cutting thread   carried out on drilling, turning and special thread-cutting (profile-knurling) machines, as well as manually. In manual processing of metals, the inner thread   cut with taps, and the outer one with dies.

Accordingly, depending on the profile of the cut thread   taps are divided into three types: for metric, inch and pipe.

Manual (locksmith) taps are usually performed in a set of three or two pieces. First and second taps thread pre-cut, and the third give it the final size and shape. Usually, the number of each taps of the kit is marked by the number of patterns on the tail. There are kits consisting of two taps: preliminary (draft) and fair. The first and second. Taps are made of carbon and alloy steel of high strength.

Dies or faceplates designed to cut the outside thread, depending on the design, are divided into round and prismatic (sliding).

When cutting threads, round dies are fixed in a special screw - die holder.

Internal threading

For cutting the inside thread   a hole is first prepared with a tap. The drill take a slightly larger diameter than the inner diameter of the required thread: if these diameters are equal, then the material extruded during cutting will strongly press on the teeth of the tool. As a result, the teeth heat up and metal particles stick to them, thread   it will turn out with torn scallops (threads), and a tap breakdown is possible.

The figure shows the cutting of the inner thread:
a - tap, b - cutting thread.

Tap design
1 - intake part;
2 - calibrating part;
3 - flute groove;
4 - shank;
5 is a square.

The following figure shows the cutting of the outer thread:
a - round die, b - prismatic (sliding) die, c - cutting thread.

Key designations:

d1 - inner diameter thread   bolts.

D2 - average diameter thread   bolts.

D1 - inner diameter thread   nuts.

D2 - average diameter thread   nuts.

P - step thread.

H1 - profile height.

d holes - diameter of the hole for cutting thread.

In order not to calculate the diameter of the hole under

thread, you can use the table.

GOST 8724- (ISO 261

INTERSTATE STAND

METRIC THREAD

Diameters and steps

Official Edition

INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION

ISS 21.040.10 Group G13

to GOST 8724-2004 (ISO 261-98) Basic norms of interchangeability. Thread metric. Diameters and steps

(ICS No. 10 of 2004)

Foreword

1 DEVELOPED by the Scientific Research and Design Institute of Measuring Instruments in Mechanical Engineering (OJSC “Research Institute of Measurements”)

2 INTRODUCED by the State Standard of Russia

3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 22 of November 6, 2002)

4 This standard is the identical text of ISO 261-98, General Purpose Threads of ISO. Diameters and steps in the range of diameters from 1 to 300 mm ”and contains additional requirements reflecting the needs of the country's economy

5 Decree of the State Committee Russian Federation   on standardization and metrology dated June 23, 2003 No. ° 201-st interstate standard GOST 8724-2002 (ISO 261-98) was put into effect directly as a state standard of the Russian Federation on January 1, 2004

6 REPLACEMENT GOST 8724-81

© IPK Standards Publishing House, 2003

This Standard cannot be fully or partially reproduced, duplicated and distributed as an official publication on the territory of the Russian Federation without the permission of the State Standard of Russia

1 area of \u200b\u200buse............................................... ......... 1

3 Definitions ................................................ .............. 1

4 Choosing diameters and steps ............................................. ....... 1

5 Thread designations ............................................... ......... 7

GOST 8724-2002 (ISO 261-98)

INTERSTATE STANDARD

Basic Interchangeability Standards

METRIC THREAD

Diameters and steps

Basic norms of interchangeability. Metric screw threads. General plan

Introduction Date 2004-01-01

1 area of \u200b\u200buse

This standard applies to general-purpose metric threads with a profile according to GOST 9150 and sets their diameters from 0.25 to 600 mm and steps from 0.075 to 8 mm.

The main dimensions of metric threads are in accordance with GOST 24705.

Thread tolerances are in accordance with GOST 9000 and GOST 16093.

Additional requirements that reflect the needs of the country's economy are shown in italics.

GOST 9000-81 Basic norms of interchangeability. Metric thread for diameters less than 1 mm. Tolerances

GOST 9150-2002 Basic norms of interchangeability. Thread metric. Profile

GOST 11708-82 Basic norms of interchangeability. Thread. Terms and Definitions

GOST 16093-70 Basic norms of interchangeability. Thread metric. Tolerances. Clearance Landings

GOST 24705-81 Basic norms of interchangeability. Thread metric. Main dimensions

3 Definitions

Terms and definitions - according to GOST 11708.

4 Choosing diameters and steps

4.1 Diameters and thread steps should correspond to those indicated in table 1.

When choosing thread diameters, the first row should be preferred to the second, and the second to the third.

Official Edition

5 Thread designations

5.1 The symbol for the thread size should include: the letter M, the nominal diameter of the thread and the pitch of the thread, expressed in millimeters and separated by an x.

Example: M8x1.25

A major step in the thread designation may be omitted.

Example: M8.

5.2 The symbol for the left-hand thread shall be supplemented by the letters LH.

Example M8x1 - LH

5.3 Multiple threads shall be indicated by the letter M, the nominal diameter of the thread, the sign x, the letters Ph, the value of the stroke, the letter P and the value of the pitch.

An example of a conventional designation of a double-thread with a nominal diameter of 16 mm, a stroke of 3 mm and a pitch of 1.5 mm:

The same for the left thread:

M16xRMP1.5 - LH

For clarity, in parentheses, the text can indicate the number of times the thread starts.

Example: М16хРМ1.5 (two approaches)

5.4. The full designation of the thread includes the designation of the size and tolerance fields of the thread according to GOST 9000 or GOST 16093.

UDC 621.882.082.1:006.354 ISS 21.040.10 G13 OKSTU 0071

Keywords: thread, metric thread, diameters, steps, conventions

Editor R.G. Goverdovskaya Technical Editor V.N. Prusakova Corrector M.S. Kabashova Computer layout S.V. Ryabovoy

Ed. persons. No. 02354 dated July 14, 2000. Put in the kit on 12.08.2003. Signed for publication on September 15, 2003. Service Print 1.40. Academic Publishing 0.65.

Circulation 1150 copies. C 11890.3ac. 786.

IPK Standards Publishing House, 107076 Moscow, Kolodezny per., 14. http://www.standards.ru e-mail: [email protected]

Typed at the Publishing House on a PC Branch IPK Publishing House of Standards - type. “Moscow printer”, 105062 Moscow, Lyalin per., 6.