Luthier Tips du Jour - Acoustic Guitar Set Up

Uploaded by OBrienGuitars on 23.03.2010

For the last several weeks or even months you have heeded the call,
got out of bed and into the shop early to begin working on your guitar.
It has been a long hard road but you are finally done and have put the strings on your new guitar.
You can hardly wait to hear the first notes come from your creation
but when you play that first chord all you can hear is…
What happened? It just didn’t turn out quite the way you had planned.
Well, don’t throw in the towel just yet.
Perhaps all your guitar needs is a good set up to make it the great playing
and sounding instrument you had envisioned.
Building your own guitar takes a lot of time and patience
and a lot of things have to go right in order to have a decent end product.
In this video I am going to assume that you have done everything correctly to this point.
Your neck angle is correct.
The fretboard has been leveled and radiused.
The Frets have been installed and the fret work done correctly.
I am only going to talk about the proper way of setting up the guitar.
If some of the other aspects were not done correctly then a professional set up may not help.
However, an otherwise very nice guitar can be rendered unplayable if it is not set up properly.
The first thing you need to do is get acquainted with the guitar
and see if it is even possible to set it up.
Check for obvious things like the proper neck angle,
and structural things like making sure the bridge is not coming unglued.
I also like to inspect the inside of the guitar
and make sure that there are no structural issues like loose bracing
or things like the top or back having come unglued from the neck block.
Once you have established that the guitar is structurally sound
then you can move forward with the set up.
The purpose of the truss rod is to counteract the tension of the strings on the neck.
It is not for adjusting the action,
although it does alter the action slightly, this is not its purpose in life.
The truss rod is used to dial in the correct amount of relief or curvature of the neck.
When placing a straightedge along the fret board
you want it to touch the frets at both ends but have a gap in the middle.
How much gap is the key.
If you depress the 6th string at the 1st and 14th frets
you can lightly tap the string in the middle around the 6th or 7th fret.
If you hear nothing then the string is touching the frets in this area.
If you hear the string hitting the frets as you tap then you have some relief in the neck.
Here is how to get the proper relief.
With the string depressed at 1st and 14th frets
slide a skinny business card under the string around the 6th or 7th fret.
It should just go under the string without moving it.
If the card bumps the string then you don’t have enough relief
and will need to loosen the tension on the truss rod.
Do this by turning the truss rod nut counter-clockwise.
If the card doesn’t hit the string then you could have too much relief
and will need to tighten the truss rod by turning the nut clockwise.
A word of caution is in order here.
If you don’t know what you are doing, don’t attempt this yourself
as you could damage or even break your truss rod.
This will ruin your whole day.
Check for the proper relief on the 1st and 6th strings using the method I have just shown.
The next step is to adjust the action of the strings at the nut.
I do this by measuring the distance between the top of the first fret
and the bottom of the string with it unfretted and then again fretted.
The difference between these two measurements is the height of the string above the fret.
On my guitars I want a gap of up to 1/64 on the 6th string
and get progressively lower on each string
until I am just a skoshe above the first fret on the first string.
This requires a good ruler that measures in 64ths
and a good set of eyes to be able to read the ruler.
If you need to make an adjustment you will need a set of nut files,
of which there are several available on the market.
If you look on the back of the package of strings you use,
you will notice the diameter for each string.
Select the appropriate file that corresponds with that string size
and use it to deepen the slot until the string is at the right height.
Notice how I am filing the nut slot at about the same angle as the peghead.
Replace the string in the slot and check to make sure it is the correct height above the fret.
Do this on all six strings.
If you happen to file a skoshe too much and get buzzing on that string,
then there is a fix for that.
Place a small amount of baking soda in the slot
and use a toothpick to strategically place a small drop of CA glue on it.
This will harden and you can then re-cut the slot being careful to not cut too deep.
The next step is to check the action at the 12th fret.
This is the distance between the bottom of the string and the top of the 12th fret.
On my guitars I set the action at 2.5mm or around 7/64ths on the 6th string
and 2mm or 5/64ths on the 1st string.
Let’s say you need to lower the action 1/64th on all strings.
You would remove twice that amount of material or 1/32 from the bottom of the saddle.
At this point you will need to unwind the strings and remove the bridge pins
in order to remove the saddle.
Notice that everything to this point has been done with the strings under tension.
The final step is to check the intonation.
This is done by playing the harmonic of each string at the 12th fret
and checking the note to make sure it is in tune.
Then play the actual note at the 12th fret on each string and see if it is the same pitch as the harmonic.
If it is then no adjustment is necessary and you have been living right.
If it isn’t then you need to make an adjustment and should probably confess your sins.
If the actual note is sharper than the harmonic then increase the scale length
by lightly filing the break angle on the saddle for that string towards the bridge pins.
If the note is flat then the opposite is true.
The human ear can hear a sharp much better than it can hear a flat
so some folks set the intonation a skoshe on the flat side just because they can.
In this video I have given a quick overview on how to set up your guitar.
If you would like to learn more about how to do a professional quality set up
then my friend Kent Everett has a video that will teach you how.