Extended use of portamento figures on guitars without locking nuts can cause the strings to be pulled out of tune.

Machinists also use the cape chisel to lock nuts and bolts so they will not loosen.

Floyd Rose introduced one of the first improvements on the vibrato system in many years when, in the late 1970s, he experimented with "locking" nuts and bridges that prevent the guitar from losing tuning, even under heavy vibrato bar use.

Specialist locking nuts exist to prevent this problem, but sometimes it is sufficient to add a second nut.

In the London Gazette of 14 April 1876 Ley was granted a patent for "improvements in apparatus for locking and fastening nuts on fish plate and other bolts".

The "box" is a cylindrical assembly, typically of bronze, comprising a sleeve threaded on one end to accept adjusting and locking nuts.

FENDER Stratocaster, '57 reissue, EMG pickups, Floyd Rose with locking nuts, beautiful mint guitar, £475.

These have since been replaced by two-part locking nuts instead of the main nuts having half-size locking nuts to hold them in place.

The PBI range of rigging screws were selected because of their bronze inserts and large surface area locking nuts, giving the maintenance staff the ability to adjust the tensions when needed.

In addition, there are locking nuts for the jazzy aluminum wheels, and the doors have mechanisms that are all but impossible to open with "slim jims," thin steel shafts that are a thief's favorite tool.