bridge placement

[jc483]

I am seeing various articles for bridge placement saying to set the center of the saddle slot at the scale length and than add a certain amount for compensation (such as 7/64). Why would I need to do this when there is already compensation built into the bridge? Can you recommend a good article fof bridge placement?

[tippie53]

Good question but I think you need an education on setting up the bridge. In most steel strings there is a compensation angle applied to the saddle on the bridge. This is to allow for intonation on steel strings. You seldom see this with nylon or gut strings.
Compensation length is different than compensation angle. We are trying to mate a static length (scale length) to a dynamic dimension ( working length of the string ). There are many ways to do this . The key for good intonation is to match the action height , string gauge , paying style and neck relief got that given guitar to set the saddle to the proper spot.
In most cases adding to the scale length of .100 to the center of the saddle along the string line of the 1st string and adding .225 to the 6th string will get you pretty much in the ball part. Then to that you can fine tune the intonation by compensating the saddle to adjust each string as needed .
If you place a saddle to exactly the length of the scale length you will tend to be sharp. The working length of the string will cause that, so you can see the need of the length compensation.

[Tony_in_NYC]

Jc,
Do you have a premade bridge with the saddle slot routed already? Of you do, you should get a KMG bridge setter and you won't lose sleep that your bridge is in the correct location. I get the feeling you have a premade bridge, so feel free to correct me if I am wrong.

[kencierp]

Precise intonation is set with a strobe tuner after the guitar has a chance to settle-in, pulled, stretched, torqued and adjust to the string tension. Natural doming etc. To get in the ball park (if you are not going to purchase a "KMG Bridge Setter) place the center of the saddle slot at the High "E" location measured from the 12th fret -- 1/2 the scale length plus .10" The machined slot angle puts the rest of the strings at the approximate location if you keep the front edge of the bridge perpendicular to the fret board center-line, and this tutor:

http://www.kennethmichaelguitars.com/saddle.html
Shows how to tweak the saddle.

[Freeman]

I am seeing various articles for bridge placement saying to set the center of the saddle slot at the scale length and than add a certain amount for compensation (such as 7/64). Why would I need to do this when there is already compensation built into the bridge? Can you recommend a good article fof bridge placement?

JC, the very simple answer is that as you stretch any string down to the fret it goes sharp. If you put the saddle at 2X the distance to the 12th fret and stretch it a little more, the note will be sharp - compared to say the harmonic or a strobe tuner. The amount of sharpening depends on the diameter of the core (and a couple of other things, but not the OD of the string). Big cores go sharper than little cores. .

The high E is moved just a tiny bit from the scale length, the low E quite a bit more. That is why the saddle is angled - but each string does have some compensation. The funky thing is that the core of the third is smaller than the 2nd, therefor it needs less compensation (or the 2nd needs more) - that is why you get the funky little notch on the B string of some saddles (or even two piece saddles). Sometimes the 6th string need a little more too.

One of the very best articles describing both the phenomena and how to compensate is by Sjaak Elmendorp in a recend issue of American Lutherie - about halfway down this page

http://www.luth.org/backissues/al101-104/al104.htm

be warned, it is highly mathematical, but following the math you can calculate the exact location for any string gauge at any scale length to make the 12th fret play in tune.

A couple of other thoughts - because the string are not fretted on a slide guitar there is no compensation. If you only play cowboy chords you probably will not notice the very slight sharpening - many old guitars had their saddles straight across. If you play up the neck you'll notice it more. Nylon string guitars do have the saddle moved farther from the scale length, just not angled (approximately same diameter, no steel core). Some people compensate the nut too - it can help with open strings. And electric guitars have the ability to fine tune each saddle break point (because players are so far up the neck).

Lastly, once I locate the bridge, when I make the saddle I leave it flat on top and move a little piece of wire around, looking for the sweetest spot to place the break angle. My 12 strings are fully compensated for each string - looks like a rip saw blade but they play in tune.

[jc483]

Good answers guys. I understand perfectly. thanks for the response. The bridges were made in our shop by the way.