# What does 6H mean on metric threads?

## What does 6H mean on metric threads?

The metric thread 8mm of ISO standard is referred to as m8 and the tolerance of threaded hole is referred to as 6H.

What are standard metric thread sizes?

ISO Metric Machine Screw Thread Dimensions

M5 5.0 0.80
M6 6.0 1.00
M7 7.0 1.00
M8 8.0 1.25

Metric thread callouts are fundamentally different because the thread pitch (distance between each thread, in mm) is specified instead of threads per inch or per mm. For example, an M10x1. 5 (coarse) thread has a 1.5mm pitch, while an M10x1. 25 (fine) thread has a 1.25mm pitch.

### How do I know my metric thread size?

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.

What does 6H mean in thread callout?

m8 means metric thread 8mm of ISO standard and 6H refers to tolerance of threaded hole (know more about it in ISO 2768)

What is a 6H thread class?

Bolt threads usually have a gap between the basic and actual thread profiles. For example: M12 x 1 – 6H/5g6g indicates a tolerance class of 6H for the nut (female) thread and a 5g tolerance class for the pitch diameter with a 6g tolerance class for the major diameter.

## What does M3 mean in screws?

The stated size of the thread M3 , M4 etc is the major diameter. I av been in engineering (37 years). The size of the drilled hole for the tap is always 10% less. So for M6 threadthe hole would be 5.4mm etc. Always important to drill the correct hole diameter or else the bolt can fail in the hole.

What is metric pitch?

Metric fasteners are specified with a thread pitch instead of a thread count. The thread pitch is the distance between threads expressed in millimetres (measured along the length of the fastener). For example a thread pitch of 1.5 means that the distance between one thread and the next is 1.5mm.

Is UNF thread the same as BSP?

UNF or fine screws have a smaller pitch, making them stronger and more resistant to damage, such as from vibration. You may also see a J, like UNJC or UNJF….Use the first number to figure out the diameter of the threads.

1. For example, on a #4-40 UNC-3A x .
2. The diameter is sometimes listed as a fraction, such as ¼.

How big is an external metric thread chart?

Standard External Metric Thread and Fastener Sizes M 0.25 – M 1.4; Metric External Table Chart Thread Sizes M 20 – M 55; Metric External Table Chart Thread Sizes M 56 – M 78 ; Metric External Table Chart Thread Sizes M 80 – M 100 ; Metric External Table Chart Thread Sizes M 105 – M 135; Metric External Table Chart Thread Sizes M 140 to M 175

How are metric threads defined in ISO 68-1?

The design principles of ISO general-purpose metric screw threads (“M” series threads) are defined in international standard ISO 68-1. Each thread is characterized by its major diameter and its pitch. ISO metric threads consist of a symmetric V-shaped thread. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other.

## What are the thread sizes of external screws?

The following are metric external thread size table chart for sizes M20 to M55 per. ANSI/ASME B1.13M-1995. These thread sizes and classes represent bolts and screws, as well, as other standard external threads.

Which is thread pitch does a metric fastener use?