Action vs. relief

[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?

[zmf]

The best way for you to answer your question is to measure the relief.

If string height at the nut works for you, and your relief is is within the correct range, then you should turn your attention to saddle height.

I confess that it's always tempting (because it's quick and easy) to tweak the truss rod to see if you can dial in a bit more back bow without making the strings buzz. But this isn't going to lower the action at the 12th fret as much as you want. Geometry is working against you.

I vote for checking with a luthier/tech for the best path forward. It could be that there's something else going on with the guitar that needs to be addressed.

[warfrat73]

Originally Posted by Jimi2

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?

Not necessarily. The truss rod has its biggest effect in the middle of the neck, which is closer to the 7th fret. If the action is ok at the 7th but too high at the 12th it's more likely an issue at the bridge... too tall of a saddle, bellying, etc.

But, rather than speculating, should probably just measure the relief. Hold down the low e string at the 1st fret (can use a capo for this) and at the neck/body joint (usually the 14th fret). Then measure the distance between the 7th fret and the low e string... you're looking for a very small gap there, like about .004-.006".

Once you've figured that out, it'll be easier to figure out where the problem is.

[Bob Womack]

Agreeing with warfrat73 and zmf, relief is a precursor to checking the string height at the 12th fret... and at the nut. You need to get the relief set right as described by warfrat73 before you can get an idea of whether the height is right at either end of the fretboard. Once you have the neck relief set, you can then move on to those measurements.

Bob

[Seb_274]

Originally Posted by warfrat73

Not necessarily. The truss rod has its biggest effect in the middle of the neck, which is closer to the 7th fret. If the action is ok at the 7th but too high at the 12th it's more likely an issue at the bridge... too tall of a saddle, bellying, etc.

But, rather than speculating, should probably just measure the relief. Hold down the low e string at the 1st fret (can use a capo for this) and at the neck/body joint (usually the 14th fret). Then measure the distance between the 7th fret and the low e string... you're looking for a very small gap there, like about .004-.006".

Once you've figured that out, it'll be easier to figure out where the problem is.

If I understand correctly, if I put capo on 1st fret and am more or less equally high on 7th and 14th fret, it calls for truss rod adjustment?

[fazool]

Action is the height above the frets - how high the (orange line) string is
This is set by the nut height at the left end and the saddle height at the right end. This is usually measured at the 12th fret (the red line distance) but should also be considered at the first fret as well for a proper setup.



Relief is how much curvature is in the (brown line) neck.
This is set with the truss rod and measured at the middle of the neck against a straight line - usually using the string itself (the blue line distance)

[zmf]

Originally Posted by Seb_274

If I understand correctly, if I put capo on 1st fret and am more or less equally high on 7th and 14th fret, it calls for truss rod adjustment?

A really good resource for everything about setting up guitars is Frank Ford's (RIP) frets.com site.

[KevinH]

Originally Posted by Seb_274

If I understand correctly, if I put capo on 1st fret and am more or less equally high on 7th and 14th fret, it calls for truss rod adjustment?

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.

[warfrat73]

Originally Posted by Seb_274

If I understand correctly, if I put capo on 1st fret and am more or less equally high on 7th and 14th fret, it calls for truss rod adjustment?

No, that is incorrect. You need to hold down the string at the 14th fret. You're using the string as a straightedge to determine how much relief/contour/concaveness is in the neck.

Holding the string down at the 1st and 14th fret basically just removes a number of variables... taking things like nut and saddle height out of the equation.

[Mandobart]

This really oughta be one of those threads permanently attached to the top for all to see. Along with Fazool's explanation of relative humidity, Andy's string changing video, description of impedance and why matching your pickup to the final input channel on your amp/PA is important, all the variables affecting what you hear on a YouTube demo of a guitar, etc.

[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.

[fazool]

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.

I feel the best sequence is as follows:

1) set the neck to dead flat with no relief at all
2) set the 1st fret action/height at the nut
3) set the 12th fret action/height at the saddle
4) set the relief

(optional 5) check intonation with proper setup and make adjustments)

[Jimi2]

Originally Posted by warfrat73

Not necessarily. The truss rod has its biggest effect in the middle of the neck, which is closer to the 7th fret. If the action is ok at the 7th but too high at the 12th it's more likely an issue at the bridge... too tall of a saddle, bellying, etc.

But, rather than speculating, should probably just measure the relief. Hold down the low e string at the 1st fret (can use a capo for this) and at the neck/body joint (usually the 14th fret). Then measure the distance between the 7th fret and the low e string... you're looking for a very small gap there, like about .004-.006".

Once you've figured that out, it'll be easier to figure out where the problem is.

Thanks, just getting around to reading responses. I guess I need a set of feeler gauges to measure?

[Russ C]

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.

I agree with this.

[JayBee1404]

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.

Originally Posted by fazool

I feel the best sequence is as follows:

1) set the neck to dead flat with no relief at all
2) set the 1st fret action/height at the nut
3) set the 12th fret action/height at the saddle
4) set the relief

(optional 5) check intonation with proper setup and make adjustments)

I’ve always understood that DDW’s sequence is the correct method.

@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?

Not claiming you’re wrong, just trying to understand the reasoning behind your methodology.