Bolts are typically used in conjunction with nuts to secure the joint.The head of a bolt is usually larger and provides a bearing surface for applying torque during installation or removal. The threaded portion of the bolt allows it to engage with the internal threads of a nut or a threaded hole in a component. By tightening the bolt and nut combination, the clamping force is generated, holding the connected components together.
What Are Bolts?
Bolts are mechanical fasteners designed to join two or more components together by creating a clamping force. They consist of a threaded cylindrical shaft with a head at one end and a threaded portion at the other end.
Bolts are widely used in industries such as construction, automotive, machinery, and manufacturing, where secure and reliable fastening is required. They are essential for creating strong and durable connections in various structural and mechanical applications.
Bolts come in various shapes, sizes, and designs to suit different applications. Some common types of bolts include hex bolts (with a hexagonal head), carriage bolts (with a rounded head and square neck), and eye bolts (with a looped head for attaching ropes or cables).
In this article, we’ll go through a complete guide of bolts, which involves bolts definition, types, dimensions explain, and the standard bolt sizes chart in metric and imperial.
The Different Types Of Bolts And Their Uses
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1.Hex Bolts
Hex bolts, also known as hexagon head bolts or hex cap screws, have a hexagonal head and a threaded shaft. They are widely used in construction, machinery, and automotive applications.
2.Carriage Bolts
Carriage bolts have a round, domed head and a square neck under the head. They are often used in woodworking, furniture assembly, and outdoor structures like fences and decks.
3.Eye Bolts
Eye bolts have a looped head, making them suitable for applications where cables, ropes, or hooks need to be attached. They are commonly used in lifting and rigging operations.
4.Lag Bolts
Lag bolts, also called lag screws, have a hexagonal head and a sharp, pointed tip. They are primarily used for fastening wood to wood or wood to other materials.
5.U-Bolts
U-bolts have a U-shaped bend and threaded arms on each end. They are commonly used to secure pipes, conduit, and other cylindrical objects to surfaces or structures.
6.Anchor Bolts
Anchor bolts are designed for securing heavy equipment, machinery, or structures to concrete or masonry surfaces. They have an embedded portion that provides stability and resistance to forces.
7.Stud Bolts
Stud bolts have threads on both ends and are typically used in applications where a nut is required on both ends for a secure connection. They are often used in flange connections.
8.Shoulder Bolts
Shoulder bolts, also known as stripper bolts, have a shoulder section between the head and the threaded shaft. They are commonly used in rotating or pivoting applications.
9.T-Bolts
T-bolts have a T-shaped head that fits into T-slots in machinery or fixtures. They are frequently used in milling machines, drill presses, and other industrial equipment.
10.Flange Bolts
Flange bolts have a flange under the head that provides a larger bearing surface. They are commonly used in automotive and plumbing applications.
Bolt Dimensions Explained – Metric Bolt Sizes/Dimensions
Metric bolt sizes/dimensions are standardized according to the ISO (International Organization for Standardization) metric thread standard. The dimensions of a metric bolt are typically expressed as follows:
- Diameter: The diameter of a metric bolt is specified in millimeters (mm) and refers to the major diameter of the bolt thread. Common metric bolt diameters include M4, M5, M6, M8, M10, M12, M16, M20, and so on.
- Thread Pitch: The thread pitch represents the distance between adjacent threads and is also specified in millimeters (mm). It indicates the number of threads per unit of length. For example, M8-1.25 means the bolt has a diameter of 8mm and a thread pitch of 1.25mm.
- Length: The length of a metric bolt refers to the overall length, including the threaded and unthreaded portions. It is usually measured from under the head to the end of the bolt. Lengths can vary widely depending on the specific application and requirements.
- Head Type: Metric bolts can have different head types, such as hex head (hexagonal), flange head, button head, countersunk head, or pan head. The head type determines the shape and profile of the bolt’s top surface.
- Strength Grade: Metric bolts are often designated with a strength grade, indicated by numbers or alphanumeric symbols such as 8.8, 10.9, or 12.9. The strength grade represents the bolt’s tensile strength and hardness.
When specifying or selecting a metric bolt, it’s essential to consider the diameter, thread pitch, length, head type, and strength grade to ensure proper fit, compatibility, and strength for the intended application.
It’s important to consult specific engineering references or standards for precise dimensions, tolerances, and specifications, as there can be variations and specific requirements depending on the specific metric bolt standard, such as ISO 898 or DIN 933.
Related Read: Nail Size Chart
Bolt Size Chart – Metric & Imperial Bolt Dimensions Chart
Check out the standard bolts size chart in metric or imperial below.
1.Metric Bolt Dimensions Chart
Here’s a reference chart showing common metric bolt dimensions based on the ISO metric thread standard:
| Metric Bolt Size (Diameter x Thread Pitch) | Head Diameter (mm) | Head Height (mm) | Shank Diameter (mm) | Length (mm) |
|---|---|---|---|---|
| M3 x 0.5 | 5.50 | 2.40 | 3.00 | Varies |
| M4 x 0.7 | 7.00 | 3.20 | 4.00 | Varies |
| M5 x 0.8 | 8.00 | 4.00 | 5.00 | Varies |
| M6 x 1.0 | 10.00 | 5.00 | 6.00 | Varies |
| M8 x 1.25 | 13.00 | 6.50 | 8.00 | Varies |
| M10 x 1.5 | 16.00 | 8.00 | 10.00 | Varies |
| M12 x 1.75 | 18.00 | 9.00 | 12.00 | Varies |
| M16 x 2.0 | 24.00 | 12.00 | 16.00 | Varies |
| M20 x 2.5 | 30.00 | 15.00 | 20.00 | Varies |
| M24 x 3.0 | 36.00 | 18.00 | 24.00 | Varies |
When selecting metric bolts, it’s important to consult specific engineering references, standards, or manufacturers’ catalogs for precise dimensions, tolerances, and specifications. These references will provide detailed information on the dimensions and properties of metric bolts to ensure proper fit, compatibility, and strength for your specific application.
2.Imperial Bolt Dimensions Chart
Here’s a reference chart showing common imperial (inch) bolt dimensions:
| Imperial Bolt Size (Diameter x Thread Count) | Head Diameter (inches) | Head Height (inches) | Shank Diameter (inches) | Length (inches) |
|---|---|---|---|---|
| #6-32 | 0.217 | 0.090 | 0.138 | Varies |
| #8-32 | 0.250 | 0.104 | 0.164 | Varies |
| #10-24 | 0.312 | 0.130 | 0.190 | Varies |
| 1/4″-20 | 0.375 | 0.156 | 0.250 | Varies |
| 5/16″-18 | 0.438 | 0.182 | 0.312 | Varies |
| 3/8″-16 | 0.500 | 0.208 | 0.375 | Varies |
| 1/2″-13 | 0.688 | 0.273 | 0.500 | Varies |
| 5/8″-11 | 0.812 | 0.325 | 0.625 | Varies |
| 3/4″-10 | 0.938 | 0.390 | 0.750 | Varies |
| 1″-8 | 1.250 | 0.520 | 1.000 | Varies |
When selecting imperial bolts, it’s important to consult specific engineering references, standards, or manufacturers’ catalogs for precise dimensions, tolerances, and specifications. These references will provide detailed information on the dimensions and properties of imperial bolts to ensure proper fit, compatibility, and strength for your specific application.