page_title: Machine head
section_title: Varieties
hierarchical_section_title: Machine head / Varieties
caption_attribution_description: reverse of the head of a folk guitar (c) 2004 David Monniaux
context_page_description: A machine head is a geared apparatus for tuning stringed musical instruments by adjusting string tension. Machine heads are used on mandolins, guitars, double basses, and others, and are usually located on the instrument's headstock. Other names for guitar tuners include pegs, gears, machines, cranks, knobs, tensioners, and tighteners.
  Non-geared tuning devices as used on violins, violas, cellos, lutes, older Flamenco guitars, and ukuleles are known as friction pegs, which hold the string to tension by way of friction caused by their tapered shape and by the string pull created by the tight string.
context_section_description: Several kinds of machine head apparatus exist:
  on classical guitars (with nylon strings), the worm gears are generally exposed; the strings are wound on the pins inside grooves in the head;
  on modern steel-string guitars, including "folk" acoustic and electric guitars, 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. Vintage and vintage-reproduction guitars frequently have individual open-gear tuners, enclosed tuners not having become common until after WWII. 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 guitars, 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.
  On some guitars, such as those with Floyd Rose bridge, string tuning may be also conducted using microtuning tuners incorporated into the guitar bridge.
  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. Steinbergers and Hohners require specialist double-ball end strings, whereas the Washburn Bantam can take regular strings.
  Presently, most worm-gear tuners provide a gear ratio of 14:1. In older designs, 12:1 was common, and lower ratios as well. Lower ratios allow a replacement string to be brought more quickly up to pitch, though with less precision for fine-tuning. Lower ratios are also more forgiving of imperfect machining, and of factors that might compromise the gear surfaces (corrosion, grit, poor lubrication).
  As increased precision of milling became more cost-effective, higher ratios appeared on the market, with 14:1 being the modern standard, trading accuracy against slower initial string winding. More recently, versions with an 18:1 gear ratio are available (particularly from Grover), and the Gotoh 510 offers 21:1.
caption: The reverse of the machine heads on a "folk" steel-string acoustic guitar. Note the enclosed gears.
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