I’m sure you must’ve wondered, as I once did, if levelling frets is nothing but a well thought out plot to get you to spend your hard earned cash at your local luthiers workshop. After all, frets are made of metal and are much thicker than the average guitar string (a fat b-string on a bass is, of course, a whole other story) ,so how much wear is there really and what contributes to how much wear we cause to the frets?
Another point you’ve surely asked yourself is “I can see there is some wear but that can’t surely affect my instruments performance?”. But what if it did and what would happen if I wouldn’t do anything about it or would the problem just take care of itself over time?
First of all, yes, the frets are made out of metal but the the type of metal can vary and with it it’s hardness. So depending on what fret material was used your frets can wear down faster or slower (for example stainless steel frets are very tough). But also your choice of strings will make a difference, again, a steel string will be tougher than a nylon string for example. And I shouldn’t forget to mention that the way we play also has it’s affect on fret wear, some of us like to really dig in when we play and bend the strings a lot, some have favourite chords or scales, like an open D or the A pentatonic, etc. And to be honest some seem to be able to corrode metal with their sweat even an Alien would get jealous… and sometimes a fret job is needed, not because of wear, but because of a raised fret or movements in the neck.
So does some wear affect on how well an instrument performs? The short answer is yes, but exactly how it will perform can vary. The most common complaint is that the instrument no longer plays in tune. One might not notice it when playing single notes but certain chords might sound awful. In this case the wear is causing the string to stretch more than it should (as well as shifting the break angle of the string to the front edge of a flattened fret) causing it play a bit sharp. Some open chords are particularly prone to this since open strings are not affected by fret wear.
Another scenario might be that you no longer can bend a note because a fret is too bumpy. It might not matter so much if you only wanted some slight vibrato but it definitely would stop whole note bends from sounding clean.
Finally, if a guitar has too much wear on certain frets it might buzz if the fret next to it has less wear and the string won’t clear it. One could always raise the bridge to get rid of the problem but at the expense of comfort.
When would it be the right time then to do something about it and can you do it yourself? It really depends on when it starts to bother you enough, you might go on for years and when you finally decide to do it you probably wonder what took you so long.
As far as who should do the job, I would strongly advice a qualified luthier. It’s not rocket science by any means but some specialist tools are needed and having done it several times before will guarantee a job well done and a smooth feeling neck.
Having spotless frets on a otherwise well setup guitar is a bit like putting new tires on your motorcycle, it’s only then when you realise what you were missing and how it made you feel on your first ride.