Why does my action suck, or why is my action so high?

Action is the distance between the bottom of your string and the top of the fret. Sounds simple, right? WRONG! (If what's actually bugging you is buzz rather than raw string height, start with What is fret buzz and how do I fix it? instead.) Listen up. Especially you, truss rod ranger, cranking away on your Jesus handle like it’s a magic freakin’ wand. You got some learnin’ to do.

You’ve got your handy-dandy string gauge ready, ok? But where are you measuring, genius? There are 132 different locations on a 6 string, 22 fret guitar where you could check. All are gonna be different numbers. Now what? Don’t start throwing around "high action" and "low action" like you know what you’re talking about. I’d bet good money you don’t. But you will! Just keep reading, and you will amaze your buddies. Secret levels now unlocking…

Tension and termination points

Guitar work is science, not art. Action is math, not voodoo. It all starts with some basic physics. You stretch this metal wire tight enough to cut cheese and suspend it across two “points of termination”, known lovingly as the nut and the saddle. The closer you get to those points, the more tension you experience on the wire – the harder you have to push for tone. The closer to the center, the more pliable – the lighter you can push for tone.

But wait, there’s more! Your string has a vibrational arc.

See how it’s wide over the frets but get tighter as it approaches the bridge (AKA the termination point)? The string needs more room to waggle in the middle. Frets 1-3 are super close to the nut. Frets 12 and up are right in the middle. Your strings cannot be the same distance from the frets in these two locations. If they were, and you removed the buzz, you’d have a sky-high nut and callouses like hardened elephant hide from the vice-like pressure you’ll have to apply to play your cowboy chords. Not good.

Golden ratio of action

Hopefully you’re still with me. It’s not rocket science, keep up. We’ve established that the space between the string and frets needs to be smaller at the 1st fret and bigger at the 12th. Great. So, how much? In math, that relationship is a ratio – and to solve it, we need to talk about what “good action” actually means, and what it’s supposed to feel like and do for you.

I have a very clear opinion on this, and my customers have all agreed with me. Good action is balanced action. Action that feels the same everywhere. FEELS the same. Not IS the same. Why? We just talked about that, so if you’re not following, go back and re-read. I’ll be here.

So what does “feels the same everywhere” actually mean? Your fingers perceive an equal amount of pressure (not distance) everywhere. The first fret and the 12th fret should feel the same to your fingers, despite the difference in distance and relative tension. Come play my guitars, and you’ll feel it for yourself.

The golden ratio of perfect action is 1:4. That’s roughly 0.020” at the 1st fret and 0.080” at the 12th, measured in thousandths of an inch. Or, for electric guitar, it’s the 15th, because of the deep cutaway urging you to rock out above the 12th. How often do I see this in guitars that arrive on my bench? Rarely. More typically I see like 1:8, 1:10 or even 1:12. Yikes!

Sometimes, I see guitars that look pretty close to right, from a ratio standpoint, but still play like crap. Good down in the cowboy chord zone, good up in the cheap seats, but terrible between 4 and 10, where a lot of your core playing really happens. This spongy zone is a clear sign that someone put way too much relief on the neck with the truss rod, and tried to compensate by lowering the saddles. Bad juju.

Nut slot problems

Nut slots are vastly overlooked and under-serviced. It’s not surprising. The price of entry into cutting them properly is $150+ in tools, plus a lot of patience and practice. It’s not really a DIY job, and most guitar techs in box stores just don’t mess with it. In a pinch, you can adjust the truss rod for more relief and kill off a little stubborn nut buzz, but that’s not a good long-term solution to a bad nut-cut.

Here’s a visual. The top diagram is your nut.

The black line represents the curvature of your fingerboard, which can vary from 7.25” to 20” with several common measurements in between: 9.5”, 10”, 12”, etc. This is super subtle, but more impactful than you might imagine. We’re looking for EVEN action, and funky-ass slots like the top diagram don’t give you that experience.

Notice how some are too high and some are too low? This is where it gets tough. You gotta cut, you gotta fill, and you gotta not screw it up. Or sometimes, you just need to make a new nut. All of these require a level of precision well beyond most people’s access to tools and patience.

Truss rod adjustments

Finally, the magic stick. In order to fully understand the truss rod, you gotta look at some basic geometry first — or for the plain-language version, see How do truss rods work?. Check this out.

At the top, the straightedge is completely parallel to the cylinder, and so it touches everywhere evenly. At the bottom, the straightedge is turned at a slight angle – not tilted up, just rotated so one end sits a little closer to you – so it’s no longer parallel to the cylinder, and as a result, it only touches in the center. You get a “high center” effect. Come to my shop – this is better in person.

Now look at your guitar neck. The strings are splayed wider at the bridge, narrower at the nut. BUT! And this is a big but. The radius of the fingerboard, the roundness, remains the same. In other words, the center of the neck is artificially closer to the strings. Again, come see me and I’ll show you. It really is better in person, with live props.

If you’re following me, this is big stuff. It defines the truss rod setting for your guitar. The rounder your fingerboard, the more your neck needs a little relief (AKA bend) to overcome that high center. Based on my experiments, the ENTIRE RANGE of possibility for truss rod adjustment is between 0.003” and 0.012” of relief. That’s a total range of 9 thousandths of an inch. Eyeball that shit, I dare you.

Putting it together

Action is a process of measure, adjust, repeat. It goes truss rod, saddle, and nut – in that order. Then, based on the live conditions of the guitar, you finagle it until it feels good. That’s it. Mathematical perfection is within reach for most guitars. Come see me, and get your guitar playing the way it’s supposed to.

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