ACTION !
Aloha again… Raven is ranting once more, this time about the most important of all things to get right when you build a guitar family instrument; and that is Action! Action! is always spelled like this, at least when I write it. The exclamation point is well deserved, and without it, you could easily forget the fact that without great Action!, your new axe is just an axe… a crude bludgeon to beat the notes into submission.
Action! is well defined within a single instrument’s realm and anticipated playing proceedures, but is harder to define correctly in a much broader perspective. For instance, a Hawaiian steel guitar has exceptionally high Action!, and is used with a metal bar to slide the notes through the melody. But to push the strings down onto the frets with such high Action! would be finger torture at it’s absolute worst. On the other hand, most well made electric guitars have exceptionally low Action!, and the finger pressure to fret out is very low indeed; small wonder that the Hendrix wannabees use them to their best potential. A well set up guitar is a pure pleasure to play. Somewhere in the middle, I am told that playing a cello can be a very serious workout for the hands and fingers, and that great Action! is everything.
Action! might be defined as the height of the strings above a certain fret on a group of similar instruments. Let’s take ukulele, as that is my broadest background, and we see that most ukes enjoy about one hundred thousandths of an inch free space between the top of the fretwire, and the bottom of the ‘C’ string, over the 12th fret. I think that’s 2.5mm, if you need translation… This is space set aside for the string to vibrate freely. The very last thing you want is to have the string set so low that in the act of striking the string, it hits the fret and loses it’s attack, grinding to a halt, being stifled by low Action! So, as a standard strategy for maintaining that free space to vibrate an .032 wound string on a 15 to 17 inch scale length ‘C’ string on an ukulele, I have never had a buzzing string whose Action! was .100 in. or higher. I use that as my benchmark for Tenor and Concert ukes. It just got more interesting, did you notice?
String Theory, musically… gets very complicated very quickly, just like it’s scientific cousin ( defining sub atomic particles). I had to learn what I needed to know about it, and find it fascinating. Of course, some folks have extensive experience with strings, gauges, wraps, cores, synthetics and even metals, but I had a lot to learn. The basics get to be repeatable pretty quick. With a given pitch that you want to hit, like middle ‘C’ on my tenor uke, a thinner string takes less force to tighten up. Makes sense, a thicker one would have to be pulled a lot tighter. In a similar way, over that distance of scale length ( Tenors are 17 inch), a smaller diameter string would oscillate less than a heavier, thicker one. When you pluck a thicker string at a higher tension, the mass vibrates bigger and wider than ol’ skinny jeans, the slim alternative. Starting from these basics, you learn how many things affect the performance of strings, and it can be a real awakening!
If you want to change the sound of your instrument, the quickest, easiest, and cheapest way to do it is to change strings. Experiment. Dive in and see how challenging it can be to develop a good set of strings that satisfy all the criteria you are looking for in a great set. They have to have balance across the spectrum, both as a standard of power and playability. Not too hard or too soft… not with a booming ‘G’ and a wimpy "E’…They need to be very closely matched to intonate correctly on a bridge that you like. If one intonates correctly a half inch away from the next string in line, then a single, thin saddle is out of the question. For any given note you plan on tuning to, let’s say our ‘C’, you can get there many ways. You could go for a silver wound .032 that takes 9 lbs. of pull or an .030 that takes 8.2 lbs.. Or .028, or .026. or .038… You could also go with a .038 Nylon that takes 9.2 lbs. of pull, or it’s slightly bigger or smaller cousin. You have several choices of diameters, brands, materials and manufacturers to severely confuse yourself with. So, enjoy the experimenting.
Then, from my perspective, you have to make it work. Action! is a big part of playability, but there are a few contributing factors to consider also. Relief is the first to come to mind. As I understand it, relief is the amount of concave bow that one might build into the fretboard, or ask a truss rod to introduce to the fretboard. This is done because the middle (half of total vibrating length) of a string will have it’s widest oscillations, and need the most space. Contrary to somewhat popular belief, truss rods are not intended to influence Action! beyond this simple principle of making way for the strings. On old time ukulele, a flat fretboard worked just fine. On a modern Stratocaster, one would expect to see some relief. If you had a capo on the first fret, and then fretted at the 18th or 20th, then used the bottom of the string as a straight edge between the first and 20th, the neck would not be flat. You would be able to fit a thin shim in between fret top and straight edge at about the 8th fret, posibbly .009 in. , or what they would call 9 thousandths. Not much… but all the difference in the world.
Another major contributing factor to playability would have to be depth of the nut slots, or Action! over first fret. Finger torture ensues when the slots are not brought down to a safe minimum. In fact, fretting on the first couple can be very unpleasant if you don’t own the several sizes of nut slotting files that an experienced luthier would collect. Each string size needs a round bottomed file of an appropriate diameter to file the slot correctly. I have about 15 of them, from .008 in. to about .056. This is how and when I use them, and the strategy I employ.
Practical: Action! starts at the saddle, on the bridge. Take the nut out of the picture, and the slots with it. Put a capo on fret one. Measure the Action! above the 12th fret for any string. Find a way to adjust the saddle to get the results you want. If it’s ‘C’ on an uke, and you’re shooting for a hundred thousands like I suggested, either carve down the saddle, the bridge, or the feet until you get there, or build it up if you are low. Do it for all strings. Don’t know what number to shoot for? Online research can be very helpful. There are chat rooms for lots of building discussions, and luthiers share pretty well. So, on my Tenor uke I might shoot for .100 in. Action! at the 12th fret for my thick strings, C and G, and less for my thinner ones. maybe .080 or even less if I was a soft and highly skilled player. On a guitar, there would be a steady declination of Action! gaps and spacing. The thick strings getting more space, the thinner ones needing less than half. Guitars with adjustable saddles are the rock stars of the group. Rotate a screw to raise or lower the string, do the same to move the saddle for proper intonation.
A string height gauge is a precise measuring tool, but feeler gauges work just as well.
When I am happy with saddle height, with a capo on the first, I then take it off to do my nut slots. I have a fancy metered little gauge that I get to read precisely what that height above the frets is, one string at a time. For my ukes, the number I look for is .012 or .013 in. for Nylon strings. I could use automotive feeler gauges like I used to, but it is the same… measure top of first fret to bottom of string. Pull out the correct size nut slot file, remove the string from it’s slot and file in a parallel plane to the headstock, down to the best height, moving slowly and carefully. Repeat as needed. The penalty for being aggressive is having to discard the entire nut and to begin again, because low nut slots make for a buzzing string, and filling in those low ones with something, anything…is not usually a good thing. On a guitar, you get six chances to mess up the nut slots, with six different files and six unique heights above first frets, and that doesn’t even broach the subject of the many ways to lay out those slots; exactly how do you want them, a very deep subject. On my mandolins, I get to file eight precise slots into each nut. Oh, the Joy!
When someone you want to impress is playing your guitar and takes time to smile and say “ Hey, nice Action!”, it is a good day. When they continue to play it and begin to put it through a rigorous workout because they are genuinely enjoying themselves, it is a great day. Without a careful attention to the concept of Action!, that might never happen. The biggest let down ever, from a builder’s point of view, is the quick rejection, and the short explanation… “It’s just not set up the way I like to play it… the Action! is too… ”. Great players demand great Action! And it has to suit their style. Maybe they have a unique attack, and need plenty of space; the Action requirements can be hard to guess. But for most of us, we want no buzzing strings and full volume when we dig in a little. We want the lowest action we can get by with, and the lightest finger pressure needed to get the job done. The numbers themselves are not as important as the outcome from a playability perspective. We won’t even get into those that are going to be bending their notes with slinky strings and whammy bars… I mean, it is impossible to cover all the faces of this very interesting topic. From string theory to nut slots, it has been a pleasure rambling on about the importance of Action!. Aloha, Raven
