Bolt-on neck is a method of guitar (or similar stringed instrument)
construction that involves joining a guitar neck and
body using wood screws as opposed to glue as with
set neck joints. The term is a misnomer, introduced
mostly by Fender whose guitars traditionally had
"bolt-on necks". Real bolted joints (i.e. using bolt
coupled with a nut) are uncommon in guitar
production. However, some aftermarket manufacturers
offer a replacement for Fender neckplates and screws
which uses captive nuts — embedded in the guitar
body by means of an external self-tapping thread —
and M4 bolts. This is claimed to permit a higher
fastening torque than ordinary woodscrews, and hence
a better coupling between neck and body.
This method is used frequently on solid body
electric guitars and on acoustic flattop guitars. In
the typical electric guitar bolt-on neck joint, the
body and neck cross in horizontal plane, the neck is
inserted in a pre-routed "pocket" in the body, and
they are joined usually using 4 screws. As screw
heads damage the wood and could put extra stress on
it, typically a rectangular metal plate or a pair of
metal plates are used to secure the joint and
re-distribute the screw pressure evenly. Such a
plate is usually criticized for making playing on
top frets uncomfortable, so, manufacturers sometimes
employ some kind of more intricate method to hide a
metal plate, smooth the angles and make access to
top frets easier. However, a visible metal plate is
usually considered as a part of "vintage" style and
they are a popular place to emboss manufacturer's
logos, stamp out serial numbers and put other
artwork.
The typical acoustic guitar bolt-on neck as
popularized by Taylor guitars is not as advantageous
as on an electric guitar. Electric guitars tend to
sound better when they are bolted together using
threaded inserts and providing for a very tight neck
joint. Acoustic guitars don't sound as good because
it makes them too bright and sometimes tinny
sounding.
Luthiers and guitar players cite both advantages
and disadvantages of bolt-on neck construction. Note
that most of these views are highly subjective and
relative. It is not easy to measure most of the
claims objectively or even compare objective
factors, as guitars differ considerably