Do I really want my neck straight?

johmica

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So, in my never-ending quest to achieve basic competency in guitar set-up and maintenance, I purchased a straight edge. Seems like the bare minimum, right?

Anyway, when I started taking a look at all of my guitars, I found that all of them, without exception, had a bit of relief in them. I'm talking about a gap between 1/32" and 1/16" at the fifth-to-seventh frets between the straight edge and those frets.

Some of these guitars have been set-up by extremely reputable guitar techs, and at least two of them have been recently Plek'ed. All of them share this relief in the neck tension.

Is this the way that it should be? I've always assumed that I wanted the necks to be perfectly straight. Is this not the case?
 

Marc Morfei

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This question has been asked every so often over the years and I am always interested. Generally I’d estimate that responses run 50-50 between flat and a little relief. I’ve been to several different techs over the years, and their opinions are split down the middle too. I was always confused about what measurements like “0.010” mean. 0.010 what? Inches? Millimeters? How do you even measure that? Finally someone told me “about the thickness of a business card.” That I can understand. So now that’s how I set mine up. Seems to work out fine.
 

KokoTele

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Lots and lots of misconceptions and old wives' tales have been passed down over the years, and neck relief is one of the biggies. Unless you like high action and a guitar that fights you, you are going to be happiest with a neck that is as close to dead flat straight as you can manage.

Fender's .010" spec is on the very high end, and I've long speculated that it's more about making sure that necks in stores don't have backbow than it is about making them play right.

I'd be surprised if you really had 1/32" of relief. That's .032", more than 3 times what Fender recommends. 1/16" is how high your action should measure at the 12th fret for an unfretted string. Most guitars don't have enough truss rod adjustment to get a neck straight from .065" of relief.

If you're eyeballing it, (and I'm guessing that you are), it's better to measure. A sheet of standard paper would make a good feeler gauge for this application. Or you could skip the measurement. Tighten the truss rod until the neck is straight, and then loosen a tiny bit at a time until you can juuuuuuussst see daylight between the top of the 8th fret and the bottom of the string.

And if you want some visual help, here's my video on the subject:

 

darkwaters

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Pick up a feeler gauge from the local hardware store. Clamp your capo at the first fret and hold down the low E string at the fret just before the neck meets the body. Start measuring and adjusting. A relief of about .008 works for me (about the thickness of a single sheet of paper). Once you’ve got the relief sorted, you can adjust your action to your preferred height.
 

Fretting out

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Dang… I like mine between .012 to .014

It’s all personal preference

On stew macs site there’s a log of famous players guitars that Dan and friends worked on and it gives all of the relief measurements
 
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KokoTele

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Perfect example today... A few weeks ago I repaired a broken headstock on a Les Paul for a customer, then did a setup. Action a hair lower than 4/64", almost no neck relief. The customer loved the way it played when he picked it up, but called me today. The guitar didn't feel right and was harder to play, like it was fighting him. He'd tried adjusting things himself, including raising the tailpiece and lowering the action, but it was getting worse instead of better.

What changed? The neck relief. It was 40° and damp the say he picked it up. It's 5° and dry today. The relative humidity in his house is probably 20%

Sure enough, the neck had about .015" of relief. Tightening the truss rod and setting the action back where he wanted it fixed it up.
 

gregulator450

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I always shoot for 0.004" to 0.008", but am willing to allow as much relief as 0.012" if the playing style and condition of the frets require it. Occasionally I get get a guitar to about a thousandth of relief with really nice low action; usually an Ibanez or Jackson will do that, and I'll set it up straight and low if the player is a shredder with a light touch. On my personal guitars, I like to get the neck as close to straight as I can with medium-low/medium action. The strings seem to ring out better at all locations on the neck and the action feels more consistent from the first to the last fret.
 

Quexoz

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What changed? The neck relief. It was 40° and damp the say he picked it up. It's 5° and dry today. The relative humidity in his house is probably 20%

Sure enough, the neck had about .015" of relief. Tightening the truss rod and setting the action back where he wanted it fixed it up.
Good point about climate change...not that kind! I like to just eyeball mine and going from dead flat at the time of leveling frets, string it up, and then check. Usually, depending on the neck wood, thickness, etc., string tension just puts a little relief, a little too much. I do the 1st fret and @the body "capo" and adjust until there is just a hair (~.003-.008 over the seasons?) width of bounce in the string at the middle. Then check often for a year as the seasons change, until it never gets totally flat and sometimes is a tad more than a hair of bounce. Most guitars it barely feels like I am tightening the truss rod at all. It will be just a quater turn or so beyond the point you feel it engage, or slight resistance in the turn.

Some guitars just have a sticky, nasty truss rod and it feels like it's always tight and sticky in all directions...I do not like that! Probably all gummed up with wood filler, splinters, Chinese sweat, and and saw dust.
 
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Wallaby

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With the guitar in playing position I hold a straight-edge alongside one of the strings with one hand, without squeezing, and slip a feeler gauge between the 8th or 9th fret and the bottom of the straight-edge with the other hand.

It's important for the straight-edge to be correctly parallel when doing this, to avoid a false measurement caused by crossing the arc of the radius.

I prefer this over using one of the strings because I can feel the gap better. The straight-edge is rigid and doesn't flex.

How are you measuring.
 
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Quexoz

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With the guitar in playing position I hold a straight-edge alongside one of the strings with one hand, without squeezing, and slip a feeler gauge between the 8th or 9th fret and the bottom of the straight-edge with the other hand.

It's important for the straight-edge to be correctly parallel when doing this.
That seems like a good way to do it too. *goes to get his notched straight edge and a guitar...wonders if his cheapo str8 edge is all that straight*
 

Wallaby

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I hear that. The one I use for this is a so-called "precision" straight-edge that can cover the entire length of a guitar neck. I try to protect it and store it safely to keep it true.

wonders if his cheapo straight edge is all that straight*
 

ghostchord

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It's hard to imagine anyone can feel a minor amount of relief vs. flat in terms of playability. So assuming you could set the same action (nut and bridge) on a flat neck or a neck with some relief I would claim that from a player's perspective they should feel identical.

So the remaining question is which method lets you get the action lower. At least if your goal is to get low action. Presumably most people are running their action somewhat higher than the minimal possible and also depending on how aggressive you play the guitar you might still get some minor buzzing.

I'm a bit too lazy to sketch the geometry on paper and actually figure it out completely but what is clear is that with a little bit of relief you get some minor amount of additional clearance while fretting the lower frets (sort of obvious) and then some minor amount of reduced clearance fretting further down than the lowest point (also sort of obvious). So if your goal is to get the lowest possible action at the nut (which helps playability) and you're willing to tolerate a slightly higher action down the neck (which IMO is not a big deal playability-wise) then a little relief makes sense. At least that's my intuition. If you sketched the geometry and did some math you could say precisely what the impact of a given relief is on any given fret...

Another thought is that it provides a little bit of safety margin if there is some minor movement, since if the neck "inverted" it could really start buzzing... You could get that margin via setting a higher action but this gives you margin and somewhat lower action at the nut...
 

KokoTele

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It's hard to imagine anyone can feel a minor amount of relief vs. flat in terms of playability. So assuming you could set the same action (nut and bridge) on a flat neck or a neck with some relief I would claim that from a player's perspective they should feel identical.

So the remaining question is which method lets you get the action lower. At least if your goal is to get low action. Presumably most people are running their action somewhat higher than the minimal possible and also depending on how aggressive you play the guitar you might still get some minor buzzing.

I'm a bit too lazy to sketch the geometry on paper and actually figure it out completely but what is clear is that with a little bit of relief you get some minor amount of additional clearance while fretting the lower frets (sort of obvious) and then some minor amount of reduced clearance fretting further down than the lowest point (also sort of obvious). So if your goal is to get the lowest possible action at the nut (which helps playability) and you're willing to tolerate a slightly higher action down the neck (which IMO is not a big deal playability-wise) then a little relief makes sense. At least that's my intuition. If you sketched the geometry and did some math you could say precisely what the impact of a given relief is on any given fret...

Another thought is that it provides a little bit of safety margin if there is some minor movement, since if the neck "inverted" it could really start buzzing... You could get that margin via setting a higher action but this gives you margin and somewhat lower action at the nut...

Two things here:

1. Players can indeed feel very small differences in things like neck relief. Our fingers are much more sensitive than people realize. Think of this: The biggest frets available are .058" tall. Typical frets labeled "medium jumbo" are around .047" tall. Just that .011" difference makes those big frets feel like railroad ties to some people.

2. Let's say you like your action at the factory standard 4/64" at the 12th fret and the neck is flat. The action at the 19th fret is about 5/64". (I just measured a Strat I had handy.)

Now let's add .010" of relief. The action at the 12th fret comes up to just a hair over 5/46". So we lower it back to 4/64". Guess what the action at the 19th fret is: 4/64" (I measured this too).

Seems good, right? But... Where is the widest part of the arc of the string's vibration? It's halfway between the fretted note and the saddle, or at the octave. And that's where we need the greatest distance between the string and the fret. Adding relief actually made that distance smaller, though.

People think that you need to add relief so the curve of the neck matches the arc of the vibrating string, but it doesn't work that way. The two curves are not parallel. Adding relief actually has the opposite of the intended affect, and increases buzzing in the upper registers.
 




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