1982 Fleta bridge that required filling and routing to
correct intonation.
Router running in the jig to produce slot. |
Setup of fretted instruments seems simple compared to orchestral
setup, at least it is “by the numbers.” Fretted instruments
warp, dip, and do all manner of contortions that shift the neck
or warp the fingerboard due to being pulled rather than pushed downward
by the strings. The principles are the same though: proper relief
to allow string swing from equilibrium and the lowest possible string
height that will play cleanly for a given player’s technique.
As always, it is neck angle to the body that is critical, so the
tops of the frets are in alignment with the top edge of the bridge.
This will give a saddle height (approximately 4mm) that will allow
adjustment for both summer and winter for many years of play as
the instrument continues to collapse.
Neck angle may be step one, but well-installed frets, leveled or
shaped into a relief because the truss rod moves the neck in the
wrong place make the difference between a clean sound or a lot of
fret noise. That also determines how high you have to set the action
to play cleanly. Correct relief coupled with the correct string
slot height at the nut enables the saddle to be set so the string
is as close as possible, depending on the player’s power of
stroke.
Intonation is the next step in the process. An old instrument’s
scale will shorten as the body collapses. Many new instruments don’t
have the saddle placed properly. They need their bridge slots filled
or may need even a new bridge in order to rout a slot in the correct
position to set the exact string length for a given string gauge.
Math may tell us to put the saddle in a particular spot, but hearing
is the true test for a given action and gauge of string. That is
why we put down our bridges with no slot and determine the exact
intonation spot with string brand and gauge with a movable saddle
and then rout the slot. Small back and forth beveling, then we set
each string to its correct intonation point.
New frets after truing a fingerboard.
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1928 Martin Triple-0-28 with new pyramid bridge, neck
set, and custom intonation.
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