Action vs. relief

[marciero]

Originally Posted by DDW

The consensus and logically correct sequence should be:

1) Check and set relief - this is unaffected by nut or saddle heights
2) Check and set nut height - this is unaffected by saddle height (or relief)
3) Check and set saddle height - This is affected by both nut height and relief

1 and 2 might be interchanged, but 3 has to come after the other two.

Good rationale for doing in this order. As a clarification though, there is some interplay among all three adjustments. While it is true that the nut height is unaffected by saddle height, the nut height is really a proxy for the height at at the first fret, which is affected by saddle height, though not much. It can make a difference though if you are right at the borderline of string buzz at the first fret, which you want to be for proper intonation and playability.

Adjusting relief changes string height at all the frets, with the affect tapering off on the lower frets and probably negligeable at the first fret.

[ljguitar]

Originally Posted by Jimi2

Stupid question question of the day!

If string height at the nut or first fret is fine, but it’s high at the twelfth, that would probably indicate a truss rod adjustment is necessary, rather than a setup, right?

My Breedlove’s strings are pretty high up the neck and I want them to come down, but they seem fine at the nut. Holding them them down at the second fret leaves little to no room over the first fret, but I think (I don’t have the guitar with me) the measurement was around 7/64 at the twelfth frets. They feel really high to me there. Would you say I just have too much relief?

Hi Jimi2
If the nut is slotted properly, and the relief is set (just slightly curved up at the headstock end), then the saddle is altered to achieve the proper height…unless there is a neck problem (very rare).

Your relief is high for me - but I'm a moderately playing fingerstyler. If you are a string bashing flat picker it may be proper.

Here's a video which will be worth the 23 minutes invested (using a guitar 'puppet')…best presentation of how adjustments affect the action.

Why is my guitar playing like crap? (Original title of the video)
Setting Action - Driftwood Guitars



https://www.youtube.com/watch?v=t_4eHPgrpmk&t=1s

Hope this adds to your knowledge of these things.

[Br1ck]

You have to start by understanding a truss rod is in and of itself, not there to adjust action. It's just part of the process.

I had a friend check out a guitar with high action. The seller told him all it needed was a truss rod adjustment. It really needed that and a neck reset, new saddle and nut. It is depressing how many people think the truss rod is how you adjust action. Dangerous as it is about 20% of the process.

[warfrat73]

Originally Posted by Br1ck

I had a friend check out a guitar with high action. The seller told him all it needed was a truss rod adjustment. It really needed that and a neck reset, new saddle and nut. It is depressing how many people think the truss rod is how you adjust action. Dangerous as it is about 20% of the process.

On the other hand, I had a friend who had been playing for years, that had guitar that he was ready to get rid of, and ALL it needed was a truss rod adjustment. He'd never even heard of a truss rod.

[fazool]

Originally Posted by JayBee1404

@Fazool - could you explain what is gained by setting the neck flat, setting 12th fret action, and only then setting relief? Surely, having set the 12th fret action, then adjusting neck relief will change the 12th fret action, perhaps only slightly, but it’s still changed?.

I think a lot of people tweak the truss rod because it does adjust the action a little. The curvature of the neck is solely intended to allow for clearance when you press the string down to the fret.

The the neck was perfectly flat and perfectly parallel to the string you would get buzzing. So you need some neck angle to create a tapering gap.

The neck curves as it bends under string tension. The truss rod counteracts that. So you want the action set independently.

But changing the relief will adjust the action a little.

I find it easier and more precise, to adjust one variable at a time.

This 4-step process is pretty well accepted

[stephenT]

Originally Posted by Jimi2

Stupid question question of the day!

If string height at the nut or first fret is fine, but it’s high at the twelfth, that would probably indicate a truss rod adjustment is necessary, rather than a setup, right?

Well, no. Check neck angle and saddle height first. Then check neck relief.

I do get a chuckle when folks swear the truss rod isn't used to adjust action. Neck relief has a direct effect on string height off the fingerboard. Of course all the other elements I've mentioned need to be correct, nut, neck angle and saddle.

I've seen guitars that were unplayable due to bad neck angle where a truss rod adjustment made them playable in the first four frets, good enough for beginners to play cowboy chords.

[davenumber2]

Originally Posted by stephenT

Well, no. Check neck angle and saddle height first. Then check neck relief.

I do get a chuckle when folks swear the truss rod isn't used to adjust action. Neck relief has a direct effect on string height off the fingerboard. Of course all the other elements I've mentioned need to be correct, nut, neck angle and saddle.

I've seen guitars that were unplayable due to bad neck angle where a truss rod adjustment made them playable in the first four frets, good enough for beginners to play cowboy chords.

A side effect of adjusting the truss rod is that it will change the action some, depending on how much you're adjusting it. It does not adjust action evenly. Adjust it too far one way, you will have buzzing in the middle of the neck. Adjust it too far the other way, you will get buzzing on higher and lower frets because the neck curve is too concave. See how that's problematic?
You set the truss rod to establish the relief you want in the neck, then adjust the nut and saddle to set the action.

[DDW]

Originally Posted by marciero

Good rationale for doing in this order. As a clarification though, there is some interplay among all three adjustments. While it is true that the nut height is unaffected by saddle height, the nut height is really a proxy for the height at at the first fret, which is affected by saddle height, though not much. It can make a difference though if you are right at the borderline of string buzz at the first fret, which you want to be for proper intonation and playability.

Adjusting relief changes string height at all the frets, with the affect tapering off on the lower frets and probably negligeable at the first fret.

My understanding of the correct way to check the nut slots was to fret the string at the second fret, and check the clearance under the first fret, which should be in the zero to a few thousandths range. If that is done, the saddle height has no relevance. It is true that when you are actually playing an open string, increasing the saddle height will increase the clearance over the first fret. In that sense they interplay. But if you have first fret buzz, correcting it at the saddle will take about 25x the change compared to correcting it at the nut, most likely with great effect on everything. Of course, as soon as you fret a string, the nut no longer matters.

[stephenT]

Originally Posted by davenumber2

A side effect of adjusting the truss rod is that it will change the action some, depending on how much you're adjusting it. It does not adjust action evenly. Adjust it too far one way, you will have buzzing in the middle of the neck. Adjust it too far the other way, you will get buzzing on higher and lower frets because the neck curve is too concave. See how that's problematic?
You set the truss rod to establish the relief you want in the neck, then adjust the nut and saddle to set the action.

Kinda goes without saying that when adjusted incorrectly, it can be problematic.

But I guess it needs to be said,... if you don't know what you're doing, don't do it or do a bit of studying on the matter before you engage.

An eighth or quarter turn at a time is a wise approach.

[nikpearson]

Originally Posted by DDW

My understanding of the correct way to check the nut slots was to fret the string at the second fret, and check the clearance under the first fret, which should be in the zero to a few thousandths range. If that is done, the saddle height has no relevance. It is true that when you are actually playing an open string, increasing the saddle height will increase the clearance over the first fret. In that sense they interplay. But if you have first fret buzz, correcting it at the saddle will take about 25x the change compared to correcting it at the nut, most likely with great effect on everything. Of course, as soon as you fret a string, the nut no longer matters.

I’ve not got a guitar in front of me, but to check the string height at the nut I always fret the string between the 2nd and 3rd fret before measuring the gap between the string and first fret. Wouldn’t fretting at the second fret always result in the string touching the first? Below are the figures I use to which seem to work well for most players.

Low E: 0.15 mm
A: 0.1 mm
D: 0.1 mm
G: 0.1 mm
B: 0.1 mm
High E: 0.05 mm

[rschultz]

Originally Posted by DDW

The consensus and logically correct sequence should be:

1) Check and set relief - this is unaffected by nut or saddle heights
2) Check and set nut height - this is unaffected by saddle height (or relief)
3) Check and set saddle height - This is affected by both nut height and relief

1 and 2 might be interchanged, but 3 has to come after the other two.

Yes, this is the correct way to think about this. Although you can lower the nut after the action is adjusted. Lowering the nut X mils will lower the action by X/2 (it's all geometry).

See below diagram. If you lower the Saddle by X, then you lower the action by 1/2 as much. Similarly, if you lower the nut slots by X, then you lower the action by 1/2 as much. You probably aren't lowerring the nut slots by more than 5-10 mils, which then lowers the action by 1/2 that. Small changes.

[rschultz]

Originally Posted by KevinH

Just depends on how much relief you want. It's easy to measure. You can use a set of inexpensive thickness gauges. Or you can do a pretty good job using a piece of paper, which is typically 0.004" (0.1mm) thick. As described by warfrat, put a capo on fret 1, hold the string down at the 14th (or 12th). If the gap at the 7th (or 6th) fret is about 1 or two thicknesses of paper the relief is in about the usual range.

Yes, you are correct about the 6th fret. Most people count frets to find the middle between the 1st and 14th... but in fact it should be the middle distance which is closer to the 6th fret. Distance between 1st and 14th is 12.7", 1/2 of that puts it at the 6th fret.