Tips for luthiers |
Depending on the design, instruments are easy or difficult to intonate. In some cases intonation has been impossible because of poor design. Here are a few thoughts and ideas based upon the problem I had to overcome while intonating different instruments. |
Adjustable neck is not necessary - if it's stiff enough
The way I see it, it is unnecessary
to make the relief adjustable by a truss rod. An instrument neck varies
in width and thickness, so the effect of a truss rod is greatest where the
neck is thinnest. Also a truss rod has no effect at all on the part of the fretboard that extends over the instrument body.
With suitable materials (steel, carbon fibres...) an instrument neck could be rigid enough to withstand the pulling force from the strings and altering humidity. There would be significant advantages:
* In this context I will recommend heavy fret wire. Big frets can be planed and crowned more times when they are worn. If you want relief it is way easier to grind it on the frets than to try to bend it with a truss rod. But above all, the instrument becomes much easier and faster to play! With thin frets you press the fingers against the fretboard as the strings dig into the soft fingertips. When the finger is stopped by the fretboard, you must press a bit more to get good contact between the string and the fret to get a clear note. With heavy frets you don't need to press that hard because the finger is not stopped by the fretboard. And there is no friction against the fretboard while sliding on the strings. |
A heavy neck absorbs less energy from the strings
An instrument neck is a bad
membrane. Therefore as much as possible of the strings vibrations should
be channeled through the bridge to the membrane. The obvious way to do
this is to make the neck heavy and rigid, preventing it from vibrating
with the strings (= stealing energy from the strings).
On the banjos I've built, the necks have glued in steel bars instead of truss rods. Some would think the necks are heavy, but I'm used to it and I don't regret it. The instruments feel very stable. When making a nut extending over the fretboard, the extension should be supported by the hard wood in the fretboard. This makes the nut more silent and less energy is stolen from the strings. |
Tilt the bridge bone backwards
On all acoustic guitars I've seen, the bridge bone
is seated at a straight angle to the guitar top. This is bad design:
Far more better would be to tilt the bridge bone backwards when the groove is routed. Advantages:
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Leave enough room for the compensations
The compensation needed is often longer than one
would imagine. In two cases (both on expensive Martin-guitars) the
compensation needed for the low E-string at the bridge exceeded the space between the bridge
bone and the bridge pin! As the bridge bone is slanted the room for
compensation is shorter on the bass side - where the most compensation
often is needed. Longer distance to the pins will also reduce the breaking
force on the bridge. Cracks between pin holes are also less likely if the
row of pin holes are slanted across the grain of the bridge. Bridge pins should be cylindrical In this context I should point out that conical bridge pins is a bad idea. They function as a row of wedges that want to split the bridge between the bridge pin holes. The bride pins should be cylindrical! That would radically lessen the risk of splitting the bridge, and manufacturing would be simpler. There is no risk that the pins will fall out or rattle, as they are fixated by the pressure of the ball end of the strings. |
Seat the nut on the same plane as the fretboard
On some guitars the bottom of the nut has the same
angle as the peghead. This complicates the making of a new nut. Also the
force from the strings may press the nut away from the fingerboard.
The nut should be seated on the same plane as the fretboard!
Why should the nut to press harder at the end of the fretboard? The wood in the fretboard is most often harder than the wood in the neck. If the nut is harder fixated against the fretboard, less energy from the vibrating strings is lost than if the nut is seated on softer wood (compare with the reasoning above about heavy neck). |
Copyright © Anders Sterner
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