How To Determine The Bolt Size

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How To Determine The Bolt Size
How To Determine The Bolt Size
Video: How To Determine The Bolt Size
Video: How to Measure and identify Bolts 2023, February

Without fasteners, a master is like no hands: you have to deal with a fixed connection of parts of various structures all the time. Bolts, screws, nuts, screws, washers are the most common fasteners. It is often important to know the size of the bolt in advance in your work.

How to determine the bolt size
How to determine the bolt size


  • - Vernier caliper;
  • - ruler.


Step 1

Bolts and nuts, similar to modern ones, appeared around the middle of the 15th century. They were exclusively handcrafted and therefore each nut-bolt combination was unique. The classic version of the connection of these two parts has been improved over the years.

Among the latest industrial advances is the development of special electronic devices capable of automatically controlling the tightening forces of this type of fastener.

Step 2

The modern bolt is a highly sought after fastener. Together with the nut, it is intended for detachable connection of parts and is a cylindrical rod with an external thread at one end and a head at the other. The head can be of different shapes: square, oval, cylindrical, conical, six or four faces.

Step 3

Most of the state standards for fasteners, including bolts, provide for the possibility of producing similar products (by general appearance, by purpose). The only difference will be in the type of bolts and their design.

Step 4

The size of the bolt depends on the application and is primarily related to the outer diameter of the thread, since a bolt is a threaded fastener. To determine the diameter of the bolt, measure its threaded outer diameter with a vernier caliper. If the thread is not applied along the entire length of the rod, then the diameter of the bolt in its "bald" part is approximately the same as the diameter of the thread when measured at the tops of the turns.

Step 5

What is considered the length of the bolt? As a rule, when designating a product, the length of its rod is indicated. Thus, the head height is not taken into account. Measure the length of the rod - get the length of the bolt. If you order a M14x140 bolt in metric measurement, it means that you need a bolt with a thread diameter of 14 mm, a rod length of 140 mm. In this case, the total overall length of the product, taking into account the height of the bolt head, for example, 8 mm will be 148 mm.

Step 6

Another parameter is the bolt thread pitch. Measure the distance between two adjacent (adjacent) thread vertices and you will get the desired size. For example, a M14x1.5 bolt is a bolt with a diameter of 14 mm and a thread pitch of 1.5 mm.

Step 7

Another dimension characteristic of some bolt types is the length of the threaded end. To find out, measure the part of the rod that is intended for screwing on the nut.

Step 8

There are many standards that set out the technical requirements for fasteners. For example, for flange connections (namely, with them bolts are used), they are set out in GOST 20700-75. Both the design and the dimensions of the fasteners are regulated by GOST 9064-75, 9065-75, 9066-75.

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