Neck relief - does the headstock lift up relative to the body, or do the central frets dip?

ToneControl

I assumed that, as you tighten the truss rod, the half of the neck nearer the guitar body essentially stays as it is, but the headstock end of the neck starts to curve upwards, I found some diagrams to show this idea:
    



but most of the diagrams  I've seen today seem to show the middle of the neck dipping down
Like this:





which is it?
the second version seems wrong to me

ICBM

That's because the second version *is* wrong .

Andyjr1515

It's just the drawings exaggerated to try to make the point.  Your first thoughts are closer.

Easiest to think it like a bow and arrow bow.  With no trussrod, there would be the tendency for the string tension to be pulling the tuners towards the bridge.  The only thing that it flexible is the neck from the heel to the tuners and so it pulls that length into a bow.

The truss rod is trying to counteract that by trying to bend in the opposite direction.  The result is that the string tension matches the trussrod tension and the neck therefore ends up straight again.  

Then, if you loosened the tension just a touch on the truss rod, the neck will start to bow again - but just by a little bit...and that is the relief

WezV

The rod type and way its installed will affect the way the neck curves (edit... as well as neck length and thickness).   but the headstock should move relative to the body however its done.

andy_k

Some of that confusion seems to me, to be the way the issue is presented.
I think some of them are illustrating the point by using the nut and last fret / string to show the bow.
The clearest example is the full body drawings, which show the neck in relation to the bridge.
There are a few varieties of truss rod around, some of which can actually create bow, as well as correct for it, I recently saw a good vid by Texas Toast which cleared up a lot of confusion for me.
The principle is the same, but in practice there are nuances. In fact, all the diagrams are showing the same things, some are just clearer.

Jalapeno

The "NOT OK - Up Bow"first example is an extreme depiction - if it's really like that, some sort of neck reset is needed as it's well past truss rod adjustment.

ToneControl

thanks guys

as far as I can tell the current consensus is to have the neck as straight as possible, adding some relief for players with heavier picking technique (like me with my 3mm pick), does that sound right?

andy_k

It all depends, on a lot of things.
A lot of it to do with how high you like the action, and how hard you play.
A well cut nut helps to get the action low enough to be able to play cleanly without being too high?????
The relief in the neck has to allow for the strings to oscillate.
It makes sense in my head anyway-sorry not very clear, but the point is, you have to make it work for your own style.

Slash'N'burn

andy_k said:

It all depends, on a lot of things.
A lot of it to do with how high you like the action, and how hard you play.
A well cut nut helps to get the action low enough to be able to play cleanly without being too high?????
The relief in the neck has to allow for the strings to oscillate.
It makes sense in my head anyway-sorry not very clear, but the point is, you have to make it work for your own style.

But then the strings oscillate most further up the fretboard where the relief is less - bridge height then nut height determines how much space the strings have to oscillate

WezV

Slash'N'burn said:

andy_k said:

It all depends, on a lot of things.
A lot of it to do with how high you like the action, and how hard you play.
A well cut nut helps to get the action low enough to be able to play cleanly without being too high?????
The relief in the neck has to allow for the strings to oscillate.
It makes sense in my head anyway-sorry not very clear, but the point is, you have to make it work for your own style.

But then the strings oscillate most further up the fretboard where the relief is less - bridge height then nut height determines how much space the strings have to oscillate

Relief is still part of it.... its a combination of all 3 things working together.  You don't need as much relief where the action is higher.

It's an imperfect system really.  The ideal would be to have a controlled curved from nut to bridge that matches the string perfectly.  Of course, it would need to be a bit different for each string of we are aiming for perfection.  

We make do with adjusting the bits we can control in the hope it's fine for the bits we can't adjust

ToneControl said:

thanks guys

as far as I can tell the current consensus is to have the neck as straight as possible, adding some relief for players with heavier picking technique (like me with my 3mm pick), does that sound right?

The consensus is to have a small amount of relief for the majority of playing styles..   you add extra for heavier picking styles. 

ICBM

ToneControl said:

as far as I can tell the current consensus is to have the neck as straight as possible, adding some relief for players with heavier picking technique (like me with my 3mm pick), does that sound right?

Pretty much. I always go for 'as straight as possible without unnecessary rattling' rather than any specific measurement.

ToneControl

ICBM said:

ToneControl said:

as far as I can tell the current consensus is to have the neck as straight as possible, adding some relief for players with heavier picking technique (like me with my 3mm pick), does that sound right?

Pretty much. I always go for 'as straight as possible without unnecessary rattling' rather than any specific measurement.

splendid
I am starting to do more of my own tweaking

btw, finally watched Gran Torino last week, so now know where your quote comes from

ToneControl

I want my workshop to look like Walt's

ICBM

ToneControl said:

btw, finally watched Gran Torino last week, so now know where your quote comes from

"Get off my lawn" wasn't quite as relevant, sadly .