Short bolting is a term frequently used to describe the situation when a bolt is installed and the thread does not fully protrude through the nut.
In order that the full strength of the nut is to be realised, it is vital that the bolt thread protrude through the nut. Failure to do so runs the risk that thread stripping will occur.
It is common practice to specify that two thread pitches
must protrude. Typically the first few pitches of the thread
can only be partially formed because of a chamfer etc. Nut
thickness standards have been drawn up on the basis that the
bolt will always sustain tensile fracture before the nut or
bolt thread will strip. If the bolt breaks on tightening,
it is obvious that a replacement is required. Thread stripping
tends to be gradual in nature. If the thread stripping mode
can occur, assemblies may enter into service which are partially
failed, this may have disastrous consequences. Hence, the
potential of thread stripping of both the internal and external
threads must be avoided if a reliable design is to be achieved.
When specifying nuts and bolts it must always be ensured that
the appropriate grade of nut is matched to the bolt grade.
In cases of when a threaded fastener is tapped into a plate or a block
it is usually the case that the fastener and block materials will be of
different strengths. If the criteria is adopted that the bolt must
sustain tensile fracture before the female thread strips, the length of
thread engagement required can be excessive and can become unrealistic
for low strength plate/block materials. Tolerances and pitch errors
between the threads can make the engagement of long threads
In summary the full height of the nut is to be used if you are to avoid
thread stripping - that is - ensure that the thread protrudes through the nut.
Also use a standard height nut as this is designed so that the bolt will break before the threads start to strip.