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Correct bridge placement
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PJ

Total Topics: 12
Total Posts: 90
Hi all - build is finished, must say did not turn out bad at all! Can anybody assist with the following? Robbie's DVD states that the scale length (positioning of the bridge) is measured from the nut down the middle of the fretboard and the middle of the bridge, to the front of the saddle slot. I have also seen authorities state that the measurement is done to the middle of the saddle, as opposed to the front of the saddle slot. Which is correct?

Sep 09, 09 | 12:06 am
mike789166

Total Topics: 8
Total Posts: 41
If you measure to the middle of the slot you give yourself a bit of leeway for setting up the saddle intonation.

Sep 09, 09 | 1:14 am
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
The bridge placement is critical. There are many influences that effect intonation. The most important is the placement of the saddle. Action height and string gauge are 2 factors.
I found that the best placement for me is this simple formula. scale length plus .125 compensation length. This will get you very good intonation. You don't want to place the saddle dead to the scale length you need a bit of compensation. You are trying to match the scale length ( static ) a non moving length to the working length of the string ( dynamic ) it is always changing. By tweaking that little bit you can now compensate each string to the saddle to get the best intonation .
John Hall
Blues Creek Guitars
Authorized CF Martin Repaircenter

Sep 09, 09 | 3:00 am
PJ

Total Topics: 12
Total Posts: 90
Thanks John - makes a lot of sense. But do I measure to the front of the saddle slot or the middle, as Mike suggests?

Sep 09, 09 | 3:54 am
Bill Cory

Total Topics: 158
Total Posts: 3584
PJ asked: "Which is Correct?"

Mind if I explore the question some?

Unfortunately, it appears that the idea of "correct" in where to measure is a function of who is instructing or who is building. Builders differ on the question of exactly where do you measure the compensation?

Stewmac, in their instructions, says to measure an additional 7/64th, to the center of the saddle slot, in the middle of the slot's thickness.

KMG, in its instructions and with its jig, says to go 1/10" to the front of the slot at the high e-string position.

John Hall says to go 1/8", and I believe (correct me if wrong, John) that he measures to the front of the slot at the high E position.

Martin says to go 1/10" to the front of the slot at the High E string.

Taylor doesn't share.

Mike Doolin customizes every guitar he builds now, but in the past, he was in the habit of removing about 1/64" from the nut-end of the fretboard, which shortened the first fret and flattened the notes fretted at the first four frets. (I did this with the "Grizzly" Western Steel String kit, and it sounded great.)

Who is "correct"? If we used a very precise guitar-simulating apparatus that had an adjustable fretboard, bridge & saddle setup, along with a device for measuring the actual frequency of a string open and fretted, we could figure out which measurement is precisely correct -- but it would only be exactly accurate with a given string, fretting pressure and action. As it is, this is a subject that just "depends." (Mostly what I think it depends on is the hearing and playing technique of the player.)

The human ear detects sharpness in tones more easily than flatness. That's one reason why we can tune some guitars to a perfect open first position E-chord, then play a first position D-chord and easily hear the sharp D on string #2. To counteract that, there are "sweet" tunings, etc., that actually tune to a compromise of flatness. There are lots of remedies, like learning not to press hard B string, etc. Which one works depends on who is playing the guitar.

So what? I dunno -- just rattling, here. My advice is to go with what John says when he answers and then get your action just right. Then tune it so you like it when you play it.

Pre morning coffee ramblings --
Bill

Sep 09, 09 | 5:06 am
PJ

Total Topics: 12
Total Posts: 90
Bill, yeah, it seems that there is a lot more to this than a simple answer. If I gather right, seems that all the measurements are done at the high E position, and not the middle of the slot (or saddle). Will definitely like to hear more opinions on this - after many hours (and hours) of finally putting it all together, I'm in no hurry to make this critical decision. Thanks to all those who have contributed so far.

Sep 09, 09 | 5:28 am
Bill Cory

Total Topics: 158
Total Posts: 3584
Except Stewmac. Their measurement is at the middle of the slot.

Sep 09, 09 | 6:08 am
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
I would go to the front of a 3/32 saddle and a touch inside a .125 saddle. Here is a point I want to show and it is dead on to what I do. As Ken shows .100 to the front of the saddle using the line of the 1st E string , If you do the math to the center .125 they are very close .
I personally will go along the E strings but both work very well. You are trying to equate a static ( scale length ) measurement to a ( string motion length ) dynamic . I found that this position will give you the best results . It is good to note the 2 different layouts , one perpendicular to the center the other along the actual string line.
I hope Ken pops in on this as I will also use the E's and I add .125 to the bass. This hits the compensation angle. If you want to use a blue grass action and be a touch higher I would use a 1/8 saddle for more comp room.
NOTE: The line I was referring to Bill in this case was actual center line of the neck in relation to the bridge /saddle .
John Hall
Blues Creek Guitars
Authorized CF Martin Repaircenter

Sep 09, 09 | 8:17 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
I am sure you are correct John, truth is a few years back I programmed all the various info points into a data base file, now that automatically loads into my CNC and CAD programs. So I simply don't actually remember the various pick off point dimensions and with my current system I really don't need to know. At least one guy on this forum is totally PO'd with me because I was unable to give him measurements along various saddle/string interesections. I just use and recommend the KMG Bridge Setter --- so in this regard I am pretty lazy. In my view the grand mistake is not getting the "B" string saddle contact point back far enough from the nut.

I like the way Kinkead explains saddle location in his book and Bill does a great job as well.

Ken

Kenneth Michael Guitars est. 1978

Sep 09, 09 | 9:00 am
PJ

Total Topics: 12
Total Posts: 90
Guys, thanks again - that is a lot of info to work off and it makes it just that more interesting. If I may say so, one of the reasons why this whole thing fascinates me so - it ain't easy, there's many problems along the way, the solutions are not always easy, but very rewarding when you (eventually) get it right. This forum really helps a lot.

Sep 09, 09 | 10:46 am
Adaboy

Total Topics: 64
Total Posts: 509
Here is the "bible" on scale length and string compensation (including nut compensation) written by David Collins in a post on the OLF (link below) Very, very good information!!! His post is roughly half way down the first page and he answered a few questions later. Save it in your favorites.....are better yet, copy it to your PC at home.

OLF Sting Compensation Post by David Collins

Sep 09, 09 | 12:58 pm
Bill Cory

Total Topics: 158
Total Posts: 3584
That's an interesting thread. It reinforces my point, above, about how there are many different ways to calculate compensation. David Collins even acknowledges them, talking about those who use .100", .110" and .125", and how those will all work okay within a 3-4 slot angle and a 1/8" saddle that has room for compensation points that will "compensate" for inaccurate or wrongly-figured measurements.

I think it's like going on a diet. If you don't combine more than one diet, and you stick to the system, it will work. But you have to stick to the whole system. In this case, it has to be the right system that fits the scale length, the strings, the action, etc. Everything in it relies on every other thing.

One of the things we non-scratch (and beginning scratch) builders have to contend with is that the saddle slots are usually 3/32 instead of 1/8, so we have less room to compensate the saddle, and the angle on the bridge is already established, so we have to go along with whatever it is, and the scale length (in which a Stewmac or Martin 25.4" is actually 25.34", but an LMI 25.4" is 25.4") is determined. So we are forced to settle on a specific compensation measurement that actually fits those parameters. But, the differences of opinion about what that specific compensation should be will still continue.

Back to the diet analogy ...
Bill

Sep 09, 09 | 3:01 pm
blues creek guitars Authorized Martin Repair Ctr

Total Topics: 52
Total Posts: 1011
When it comes down to it , there is no such thing as a perfectly intonated guitar. But that is when compared to each fret. I know I had posted a primer a while ago to help explain this in more detail. I agree the important thing to this is to have compensation ability. Also you won't see a compensation angle on classical.
Scale Length : This is the static dimension of the placement of the frets. The scale length can be anything
String Length: The length of the string at rest from the nut to the contact point of the saddle
Compensation Angle : Martin uses a 3 degree angle , I have seen others with a 4 degree , this is figured to help with intonation of the instrument by figuring the working length of the string
Working Length : This is the length of the string when in motion. Since the string is not at rest , the strings length is in constant flux. This is what drives the saddle. This length will change as the properties of the string change .
Compensation Length : This is the actual manipulation of the saddle by adjusting the length of the string so you can intonate each string.
Action Height : This is one of the major contributors of playing havoc with intonation , when you set your intonation to a given string height and things change , the more or less you pull the string to fret , the more or less tension is applies thus changing pitch.

All of this together is what you are juggling to get your guitar to intonate. So this may help explain some of the differences . The key is to get the saddle into a position that you can manipulate the physics to get the tuning right.
If you set the saddle short you will be sharp , and if you set it too long you will be flat. It is key to note that the farther you are from the saddle the less noticeable intonation problems will be. The higher up the board you are the shorter the string and the tighter the tolerance.
When compensating a saddle you want to use the 12th so that you are in tune at zero and 12.

I hope this help clearing things up a bit. Dave's posting is very informative. I just hope this helps some of you.
John Hall
Blues Creek Guitars
Authorized CF Martin Repaircenter

Sep 10, 09 | 3:20 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
If you doubt that this is kind of a "crap shoot" just take a good look at the Gibson Tune-o-Matic bridge found on almost all their electric guitars (Epi's too) note that there is adjustment for bridge/saddle height, angle as well as, adjustments for all the individual strings --- the designers (Gibsons and most other electircs) know full well that all these dimensions are moving targets based on the all the factors mentioned above. In fact at one time the Gibson acoustics had plastic bridges that included some of these adjustable features. So as far as a "Bible" of specific measurements "one fits all" -- not going to happen, again its a math thing. So for the new comers its important to get the saddle in a workable location. Note that for instruments that I set up that were used for recording, its was not uncommon to install saddles as wide as 3/16" to get intonation correct. Don Teeter has excellent info regarding this subject in his books.

Ken

Kenneth Michael Guitars est. 1978

Sep 10, 09 | 7:09 am
Kevin Sjostrand

Total Topics: 84
Total Posts: 981
I am a complete novice here, but after making my first guitar with a standard Martin style bridge with 3/32" saddle, and seeing that there is not much room for adjustment, on my second build I've cut a 1/8" saddle slot just for the reason of "hopefully" having a little bit more play room for making the compensation adjustments. From what you guys are saying, this can be a good thing!

Kevin

Sep 10, 09 | 7:31 am
Ken Hundley

Total Topics: 40
Total Posts: 2169
I'm experimenting with a 3/16" saddle. Just can't leave well enough alone, I guess ;)

Sep 10, 09 | 10:29 am
Herman

Total Topics: 38
Total Posts: 480
For my 28" baritone with heavy strings no one would or could give me the exact compensation. On the net I just found rough directions. d'Addario told me they didn't have a clue (?!) and expert David Berkowitz didn't reply my mail. So I was on my own. Therefore I decided to make a saddle 1/8" wide. That will give me some space to work with. The saddleslot is positioned with a compensation of 0.118" on the high E and 0.256" on the low E. Time will tell me if this is appropriate. I'll let you know.

Herman


Sep 10, 09 | 12:18 pm



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