Something to Fret About

Frets on Early C. F. Martin Guitars

Early Martin guitars have bar frets, which were made of a simple straight length of nickel silver with a rectangular cross section.  The top was "crowned" to create a slight curvature to soften the sharp right angles, while the side facing the fretboard was nicked slightly to create small burrs that helped to keep them from coming loose. 

Martin changed to "T" frets in 1934, at the same time as the introduction of the steel rod, also in the shape of a "T".

Some folks find the bar frets to be a bit rougher on the fingers, with their tall squarer profile, than T frets, which have a wide area on top with a softer, more rounded contour.  Those with experience generally find they adapt to bar frets with time, and appreciate their more precise fingering and sound.

Early Martins had no fingerboard reinforcement.  An ebony rod was added in the 1920's until the steel "T" rod, similar in construction to the blade of a snow sled, appeared in 1934.  The "T" bar was replaced by a square tube in 1967.

Luthiers have often unknowingly replaced worn bar frets with T frets, not knowing that the bar frets,
exerting a sideways pressure when wedged into the fingerboard, are a necessary part of a system that keeps the neck straight without the use of a reinforcing bar.

In about 1977, Matt Umanov, in New York City, suggested something innovative - "shimming the frets" to correct the neck of my 1930 OM-28, which was not only curved, but "wavy".
  Since new bar fret material was no longer available at the time, it was common for luthiers to add shims underneath the frets, to raise them enough to give them a bit more life when the height of the frets were worn down.  Matt suggested something different.  He explained to me that by adding extremely thin shims to the sides of the frets, adding width to the fret material would exert a pressure on the adjacent fingerboard which will push the adjacent area of the neck downwards to selectively affect areas of curvature of the neck.

In the years since, as bar fret material has become available once again, a number of skilled luthiers have begun to keep a supply of bar fret material in various widths which they can carefully select for a "compression re-fret" to correct the curvature of the neck.

1840's Martin Alternative X Spanish Guitar

T Frets

 T frets are also made of nickel silver, although brass frets were used at times in 1945 when the wartime effort limited supplies.

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