Note: If you have a bolt-on neck design instrument whose adjustment nut is concealed by the body, loosen the bolts and strings as little as possible to tilt the neck heel upwards and access the adjustment nut.

Note: Some necks do not respond instantly to truss rod adjustments. The wood may take a little time to respond to the altered tension. If you made significant rod adjustments and do not see a change in relief, set the instrument aside for up to 24 hours then re-check.

Optimizing Neck Relief

The optimal neck profile for most guitars and basses is not dead flat. Strings vibrate in an elliptical shape, thus most guitars and basses benefit from a neck that has a very slight amount of relief, which will match the elliptical shape of the strings' vibrations. Read the relief of your instrument by fretting an outside string at the first and twelfth frets simultaneously. Generally, an optimized neck will have about a business cards' thickness worth of space between the string and the sixth/seventh frets. There are exceptions to this rule however; some instruments require more relief than described and some work perfectly with no relief at all (flat neck).

If your instrument's neck has more than a business card's thickness worth of relief, you may need to tighten the truss rod. If the instrument develops fret buzz from this adjustment, loosen the rod back to its starting position; it may already be optimized. If your instrument's neck has less than a business card's thickness worth of relief, but does not have fret buzz, it may already be optimized. If your instrument has less relief than the business card's thickness and the frets do buzz, you may need to loosen the truss rod to optimize the relief. An optimized neck will have better tone, sustain and action and will be less prone to warping over time.

While the business card method is a good standard for setting relief and improving the playability of most instruments, it does not take into account the unique characteristics of the individual instrument. The next Xylem article will cover how to fine-tune a truss rod and eliminate some fret buzzes using the truss rod. It will also present specific examples of how to correct upbowed, backbowed, flat and twisted necks by adjusting the truss rod.

Copyright © Anthony Olinger, Xylem Handmade Basses and Guitars 2008.