Nuts, truss rods and machine heads

Often overlooked, the nut is a critical piece of your instrument - if this is cut wrong or less than perfect it can lead to all kinds of issues, such as poor intonation, poor note quality and tuning instability. A nut with too deep slots can cause binding, where the string effectively gets 'stuck' in its slot - if you've ever heard your guitar 'ping' when tuning, it's a sign that the nut needs attention! The break angle of the string in the nut can also be a source of intonation problems - if the string is supported on a high point anywhere behind the front face of the nut (due to poor factory installation) the guitar will be very difficult to intonate properly - this means that it's in tune at the first few frets, but gets progressively more and more out of tune as you go up the neck… Ideally, the nut ought to hold the string a fret's height above the fingerboard - in practice most nuts are cut too high and will always benefit from a fine-tune. Simply, a correctly fitted and adjusted nut is essential to get the best from your guitar.


Also, the pointy end of your guitar is where you'll find the truss rod adjustment nut, usually lurking about under a plastic cover. (The truss rod is a curve-adjustable steel rod that goes up the middle of your neck to counteract the force exerted by the strings - this can be over 200lbs/sq. inch, so you can see how significant this hidden bit of metal is!) The neck usually has a shallow forward bow to accommodate the vibrating strings and is a critical factor in the overall set-up and feel of your instrument - this curve interacts with the height the bridge is set at the other end of the string and requires a delicate balancing of several factors to 'get right', bearing in mind the gauge of string, the playing style of the individual and the condition of the frets. You may notice that your guitar changes on its own when the seasons move from summer to winter and vice-versa, as the changes in relative humidity affect the neck woods. This is particularly noticeable if your guitar has a very low action.

truss rod

Lastly, the pointy end is where we'll find the machine heads - not too much can go wrong with these as they are based on a simple worm-gear mechanism. I've often heard people blaming poor tuning stability on 'crappy' machine heads - the reality is probably more to do with poor string-winding technique and an imperfectly cut nut… There are many types of machine head available - from vintage style split posts to locking tuners and everything in-between. There are many legitimate reasons for wanting to change out machine heads on a guitar - some neck-heavy instruments benefit from a change to light weight tuners, whilst traditional strat-style tremolo systems just love to be coupled with locking tuners.