intonation primer

[tippie53]

When setting up a guitar , how can I be sure I will have good intonation?
This is a common question and one that has many answers. I hope this explaination will help you underrstand what it is and how you can make the best adjustments for your situatation
1st , What is intonation?
This is matching the strings working length to the static length of the frets on the fret board.
2nd How can I do this ?
First you have to understand and control the individual variables and since this is individual to each guitar you need to identify them so you can control them. so lets look at this and follow the stages of what we can do.
First there is a lot to do with the prep of the fretboard. The fret board needs to be as true as you can make it. Once installed on the neck you need to place the saddle carefully as possible. I like to measure nut to 12th and doube that . Then following the 1st string ( hi E ) and I add .100 to that to the saddle slot center. I then add .125 for the bass side.
The typical bridge as a 3 degree compensation angle . To help your intonation set up you can look at saddle placement or saddle thickness a way to help make adjustments for the saddle to get your intonation as close as you can. The wider the saddle the more adjustment you would attain , to a point.
The next point would be what is your normal action height , a flat picker may need more height than a finger picker , the more height the easier it is to pull the string sharp.
You have to accept that you will not have perfect intonation on every fret , so you want to do the set up the guitar to the players style. So lets look at this from the extreems , a blue grass flat picker and an easy finger picker

FINGER PICKER Light Intonation adjustment
In the case of the ligher player I may use a 3/32 saddle figure a light 2-3 action
this means 2/32 and 3/32 action height on the 12th fret. Here I will want to set things up as to my players style , so the higher up the neck I want to be sure I take that into account.

I set the bridge as state with a 3/32 thick saddle. I put a .125 radius on the top of the saddle , I check in this order
1 relief ( .006 at the 6th fret ) This is the line from the 1st fret to the 12th fret.
( I set something under the nut set 10 to 12 lb on the guitars shoulders to simulate string tension and keep this on until I add strings )
2 set the nut slot ( .010) off the top of the fret plane
3 using a straight edge resting on the 1st fret and on the saddle , measure the height at the 12th fret. This is following the line of the 1st and 6th string. Then I can make the rough saddle.
Now I can string the guitar. I like to string with the same gauge string the customers want to use. Once strung I check the adjustments.
I like to set the relief again and now I can adjust the nut slot. I will take the nut slot to .006 over the fret plane and tune to pitch. We are assuming the frets were dressed and ready for stringing
Now with the strings tuned I can check the action height and adjust the saddle then I check the harmonics on the 1st and 12th fret. I do want to see within 3 cents on intonation on a raw saddle. I do not mind seeing a touch flat as the ear tends to pick up sharp faster than flat.
Now I can , if I have to adjust the sadlle to each string. Another reason I don't mind seeing a touch flat , is that players will often pull on the string and this can pull the string sharp.

On a blue grasser I will keep the nut about .007 to .010 with relief of .06 to .010 . This situation I tend to work with a thicker saddle . I also set the action here at 2 1/2 32th and bass on 3 1/2 32th. I prefer a .110 saddle . I do that same process of relief , nut and saddle. , then adjust the intotanation. While most blue grassers tend to play in the 1st postion, you still want to do the 1st and 12 fret. A hard flat picker may have a heavier fretting hand so it allow 3 cents flat on intontaion on 12 fret and use a light touch when adjusting. That permits the player some fretting pressure . The closer to the fret you touch the less you pull sharp the farther back the more it will pull sharp , Try it , you will see.
I hope this information helps youl

[B. Howard]

John, I notice that the one set up is measured in 32cnds while the other is on 64ths. Just wanted to be sure that there was not a typo there. I usually make all my measurements in 64ths, by the half, like you did in the second example. Thanks for all the great info.

[tippie53]

yup me fix