British Standard Fine

A bolt ( or nut ) with fine thread has compared to the regular thread a narrower thread profile. To distinguish it in addition to the outer diameter of the measure of its - in slope - also smaller. For example, the rule thread M 20 has a pitch of 2.5 mm. Fine threads with the same outer diameter of 20 mm x 20 M 2; M 20 x 1.5 ( see figure); M 20 x 1 or even smaller slope ( in question are all normalized pitch dimensions).

Fine thread can be found at metric ISO thread and the Whitworth thread, as well as the American Unified Thread Standard.

Applications

Use cases for fine-pitch threads:

• Screws, for example, of measuring instruments, as they allow a more precise adjustment for the smaller hubs (they are sensitive ).
• When there is little space for the thread is available in the radial direction, such as when the thread needs to be mounted on a hollow component with low wall thickness, so that the gears of a standard thread would cut too deep.
• In order to increase the load capacity. A fine thread has a higher capacity than a standard thread, partly because of the larger core diameter (load-bearing cross-section of the bolt ).

Because of the lower slope of the self-locking is better than regular thread. One can dispense with a screw lock under certain circumstances.

On the basis of two other figures, the Fühligkeit and self-locking is explained in threads. The thread Imagine only settled.

Extract from DIN 13-2

Dimensions in mm.

Unlike the standard thread

The standards ( for metric threads ISO 261 ) specifies not only the rule threads, so-called fine threads, which are characterized by a lower slope ( height of a thread turn):