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Machine Head




A machine head, also called a tuner, tuning peg, or tuning machine, is part of a string instrument ranging from violins to guitars to double basses, an apparatus for tensioning and thereby tuning a string, usually located at the Headstock . A headstock has several machine heads, one per string.


CONSTRUCTION AND ACTION


Traditionally, a single machine head consists of a pin, mounted at the center of a Pinion gear, a knob or "button" and a Worm Gear that links them. The pin has a hole through the far end from the gear, and the string is made to go through that hole, and is wrapped around the pin. To complete the string installation, the string is tightened by turning the pin using the tuning knob. The worm gear ensures that the pin cannot turn without a movement on the knob; it also allows precise tuning.

The guitarist adjusts the tension of the various strings using the knobs so that they are correctly (23.3  Lbf , 103 N ) to 13.8 kgf (30.2 lbf, 135 N).


VARIETIES


Normally, worm gears provide a Gear Ratio of 14:1, though versions with 18:1 gear ratio also exist. They provide better accuracy in fine tuning, though are somewhat slower for initial string winding.

Several kinds of machine head apparatus exist:
  • on Classical Guitar s (with nylon strings), the worm gears are generally exposed; the strings are wound on the pins inside grooves in the head;

  • on steel-string guitars, including "folk" Acoustic Guitar s and Electric Guitar s, the worm gears are generally placed in individual sealed enclosures with permanent Lubrication , although budget models may have exposed gears fixed on plates housing a row of gears; several machine head placements are possible, depending on the shape of the Headstock :

  • --- rectangular head, 2 rows of 3 pins (or 6 pins for 12-string guitars): found on most "Folk" and "Jazz" guitars and on Gibson Les Paul guitars;

  • --- a single diagonal row of 6 pins: found on Fender Telecaster and Stratocaster guitars;

  • --- one diagonal row of four pins and one diagonal row of two pins: found on Music Man guitars;

  • on Bass Guitar s, where string tension is extremely high, larger, heavier-duty machine heads than those used on guitars are used. Bass tuners generally feature larger knobs than guitar tuners as well; often these are distinctively shaped, and known as "elephant ears." Gear ratios of 20:1 are used often. Exposed gears are much more common in premium bass guitars than in six string non-bass instruments.



Since , locking ones are about 50% more expensive than original. Many break strings when tension is increased while the mechanism is locked and later unlocked, which frequently happens in music stores.

Note that on some guitars, such as those with Floyd Rose bridge, string tuning may be also conducted using ''microtuning'' tuners located at guitar bridge. In this case, main machine heads at headstock may be missing entirely, as well as the headstock itself.

Likewise, 'headless' guitars and basses, notably those designed by Steinberger and their licensed imitations, such as the Hohner Jack Bass, and unlicensed imitations such as the Washburn Bantam, have the machine heads at the body end. Steinberger s and Hohner s require specialist double-ball end strings, whereas the Washburn Bantam can take regular strings.


NOTABLE DESIGNS


Several manufacturers established well-known designs of knobs and whole machine heads. These designs are subject to copy and reference:


REFERENCES


There are several US patents on machine heads, mostly covering various aspects of locking:

  Number 5285709
  Y 1994m=02d=15
  Inventor John D Grant


  Number D388817
  Y 1998m=01d=06
  Inventor Han Soo Kang


  Number D389508
  Y 1998m=01d=20
  Inventor Han Soo Kang


  Number 6078001
  Y 2000m=06d=20
  Inventor Han Soo Kang


  Number 6580022
  Y 2003m=06d=17
  Inventor Han Soo Kang