The size of a metric screw or bolt is specified as diameter, pitch and length, in millimeters (millimeters is abbreviated “mm”). For nuts, size will appear as diameter and pitch. … In the example above, a pitch of 1.0 means that from one thread to the next thread, the distance is 1.0 millimeter.
How are metric bolts identified?
The metric screw thread is identified by the capital letter M, followed by the nominal diameter. Metric threads are measured by the distance between two adjacent threads in millimeters (pitch). Threads on a standard (inch based) fastener are measured by counting the number of threads per inch.
How are standard and metric bolts marked?
Systems of Bolt Grades
Bolts are made of different grades of steel. … The SAE marking system uses raised dashes on the bolt head to indicate strength. Metric Bolt Grades—Metric grades are set according to rules set by the ISO (International Standards Organization). The grades consist of two numbers separated by a dot.
How do you specify bolts?
The size of a metric bolt is specified using pitch, diameter, and length in millimeters. For example, in M8-1.0*20, the “M” means the Metric thread designation, the digit 8 refers to the Nominal diameter (in millimeters), 1.0 refers to the pitch, and 20 refers to the length.
How can you tell the difference between metric and SAE bolts?
Metric and SAE fasteners are measured differently and with different vocabulary. SAE nuts, bolts and screws are measured by their thread count, or TPI (threads per inch) and their length. Metric fasteners are measured by length and pitch, or the distance between threads.
What do the numbers mean on metric bolts?
In addition, most metric bolts are identified by a number stamped on the bolt head, such as 4.6, 5.8 or 10.9. The number has nothing to do with the size, but does indicate the relative strength of the bolt. The higher the number, the stronger the bolt. … A metric fastener could be designated M12 x 2, for example.
How can you tell the difference between metric and imperial bolts?
Telling the difference between a metric and imperial bolt is easy. If the bolt has lines on the head its standard or imperial. If the bolt has numbers on the head then its metric.
How are bolt sizes measured UK?
To measure the diameter of screws and bolts, you measure the distance from the outer thread on one side to the outer thread on the other side. This is called the major diameter and will usually be the proper size of the bolt.
What is the standard pitch for metric thread?
ISO 724 specifies basic dimensions of metric threads in accordance with ISO 261. Dimensions refer to the basic profile in accordance with ISO 68. The pitch varies from coarse to extra fine with up to 5 different pitches for some dimensions. The thread angle is 60o and the thread depth is 0.614 x pitch.
Do metric bolts have different threads?
Metric fasteners are specified with a thread pitch instead of a thread count. … For example a thread pitch of 1.5 means that the distance between one thread and the next is 1.5mm. In general smaller fasteners have finer thread so they have lower thread pitch.
How do you tell the difference between metric and standard sockets?
SAE sockets are sized in inches and fractions of inches. Metric and SAE wrenches have different systems of measurement. Metric sockets and wrenches use the metric measurement system. This is when millimeters are used to describe the size.
How are metric threads measured?
For Metric parallel threads, taking a caliper reading of the threads outer diameter in millimetres (mm) will give a reading of the exact thread size but not the thread pitch. For example, a caliper reading of 12.03mm indicates it is very likely a 12mm thread.
How do I choose a bolt size?
A typical rule of thumb . . . Use a bolt diameter that is 1.5 – 2.5 times (up to three times) the thickness of the thinner material you are bolting together. So, for 1/8″ material, a 1/4″ diameter is often a good bolt choice. For 1/4″ thick material, perhaps a 3/8″ or 1/2″ bolt.