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Ok this question might be streange as I have almost completed 5 guitars now. BUT. After re-watching Kent Everetts intonation video I got a bit puzzled when I then went to Stew-macs fret position calculator ! Accordingly to Everett I should measure like always= double 12th fret..... and then add compensation. In my head I have always added 1 mm on the treble and about 4,5 -5 mm on the bas side. BUT, when i went to Stewmacs calculator. I added the numbers "22 frets" & "24.625" scale lenghts.
In my head this would in mine "and everetts" world (if I have understood him right) in mm ! to the sum of :

For treble 24.625*2.54= 62.547 + compensation 1 mm = 62.647
And for bass = 62.547 + a compensation of 4.75 mm = 63.022

Stew macs calculation, including compensation = 22 frets, 24.625 scale.
T= 62.76
B= 63.07

How big a differens are these 2 (stewmac & Everett)
Everett speaks of adding the normal 1/8", + 1/16th extra that he says compensates for how the guitar is used in the real world compared to what the tuning machine says. "what the ears likes to hear" SO, what should I go by, as Stewmac also says their compensation is taking in consideration of how the guitarist is playing.

Lars.

I haven't used the StewMac calculator, so I don't know what the inputs are. I do know that it's not as simple as just the string gauge and scale length, and that even if you input the action height at the 1st and 12th frets there's scope for significant error.

Besides, there is simply no way you will get any guitar that has straight frets to play in tune for every note on every string. Intonation is a will 'o the wisp; all you can do is try to come close.

In this case, you're worrying about a few tenths, or hundredths, of a mm. When I cut my own fret slots I go for +/- .2mm tolerance. Nobody has complained yet: in fact, one customer who is particularly fussy about that has complimented me on my intontation.

If you're concerned, try checking your intonation with a really accurate tuner. You might be surprised.

I huge source or error in compensation comparisons is that some quote a figure to the front of the saddle slot, while some like the stewmac calculator work to the centre of the slot.

I just built a guitar to this scale and used the Stewmac numbers as near as I possibly could.
Nut to front of saddle edge. I used the thick saddles they sell 3/16ths or something like that
I found I still had to compensate e and b ( ie make the string longer)
as a result of sharp notes when fretted on the 12th. I have a suspicion that a couple of the other strings might need a bit but they were so close I couldnt hear it. The strings were light 12's
So for what its worth I would use the longer measurements and a thick saddle to give you some room to work with

Yeah, I used the Stew-mac calculator for the first time a few weeks ago... and had my first few bridge removals (on my own guitars) as a result. I don't believe they mention that their measurements are to the center of the slot. So all the strings were too long, but coming off the front edge of the saddle. Oh well, live and learn.

Thanks Alan for your answer. I ment this in the most simplicity as possible. I do know that it has more to do with everything like string-thickness, stringhights etc. But I was more thinking in general.
you wrote [quote]If you're concerned, try checking your intonation with a really accurate tuner. You might be surprised./quote] But that is just it ! In Everetts video he explaines that one cannot go by "only a machine, as the real player slightly bends the strings as playing etc. he says that he intentionally intonates the guitar out of tune slightly and as the guitar is "played" it becomes in pitch. this is where I am a bit lost. ! I think I understand him but not perfectly.

All good inputs, thanks. Would love to get more if anyone has anything to add .... And yes thats good news to hear that stewmac was reffering to center of slot. as I am thinking of beginning of slot + about 1mm on high E and + 4.75 to END of low E in my way of thinking. Then make a straight line between beginning of High E to End of Low E.
Would this be wrong ?


Lars.

The number of frets in the Stewmac calculator is used only calculates the divisions on the fretboard. Based on basic 12th root of 2 calculations. The compensation of the saddle has nothing to do with the number of frets. If you have a scale of 25.400” the Stewmac calculator will give a compensated scale length of 25.489” + or -.030” at treble E and 25.614 + or -.030”. At 25.400 scale that is .089” [2.26mm] compensation at treble E and .214” [5.44mm] at bass E. these dimensions are from theoretical nut break point to theoretical saddle break point. I.E. edge of nut to the centerline of the saddle. Basically the Stewmac calculation takes the basic scale length and multiplies it by 1.0035” [25.4889mm] to find the treble e compensated break point location and 1.0089 [25.626mm] to find bass E compensated break point location. Regardless if you have 2 frets or 22 frets this compensation is the same for this scale. the + or -.030" is just a value that Stewmac assigned by assuming that the average hobby builder is likely only to measure accurately to with in 1/32" (.03125") [.7938mm].

Measuring to the centerline of the saddle allows for set-up fine intonation to be moved either direction as needed equal to 1/2 the width of the saddle or less. If you se your comesation location at the front edge of your saddle then you can only intonate longer not shorter if need be.

Thanks alot Michael. So tell me then as this is how I am doing it, would you say I am doing it right then.
I am doing beginning of slot + about 1mm on high E and + 4.75mm to END (back) of saddle for low E in my way of thinking. Then make a straight line between beginning of High E to End of Low E.
the one I am working on has a scale lenghts of 24.625
any recommendations ?

Well compare for your self. I don't know for sure what your saddle thickness is.

per Stewmac calculator

24.625" [625.475mm] scale

Treble "E" 627.655 mm
Bass "E" 630.738 mm

per you (based on a 3/32" [2.3812mm]wide saddle)

Treble "E" 626.475mm +1.1906mm (1/2 of 3/32" saddle)=627.665mm
Bass "E" 630.225mm + .1.1906mm (1/2 of 3/32" saddle)=631.415mm

(actually the extra distance is a bit more than 1/2 the saddle width due to the angle but 1/2 is close enough to use for this.)

your real close to dead on per Stewmac at the treble E and .677mm long at the bass E

Just use the stewmac figures to the centre of the saddle slot and you will be fine
Measuring to the front and the back of the slot just complicates things.

That is not always easy to measure to and that is why most use the leading edge of the saddle slot.

Thanks alot, great help . just for the record, my saddle thickness is 4mm.

Lars.

in my data I found this
x = 0,15" (3,81mm)

is it ok?

OK replace the add lenght with 2.0mm

By the way. ther is something I have ment to tell you for a couple years now. I worked with a guy nmed Steve Stahl that looks like a dead ringer for you but with longer hair.

The problem with measuring at the center of the slot is tht you can tilt the bridge either direction and maintain that location and the 1st and 6th stings can be almost any thing. Always measure along 1st and 6th string path.

Also the X varies with the scale length. not a lot and .15" works ok for most players ears

Sorry Michael. Dont know him . although here´s a photo of me taken as I was in California a few years back. I might be that steve after all .
allthough the hair is gone now haha. didnt like the balness that was building up on the back-part of the head

by the way the conversion factor for inces to mm is 25.4mm per inch not 2.54mm per inch that is where you were getting such a small compensation figure from 24.625"=625.475mm not 62.5475

Lars was using cm which just tends to confuse things.
I agree measuring to the centre of a slot can be difficult
I just work out compensated string length at e and E then deduct half saddle width and distance from front of saddle to front of bridge at e and E.
I can then mark these measurement on a piece of paper taped to the soundboard and just line up the front of my bridge to this

Yep that is pretty much what I do as well and what I was trying to express to Lars

Yep that is pretty much what I do as well and what I was trying to express to Lars

man this photo reminds me of a british rocker from my teen years "Long John Baldry'


Now don't try to lay no boogie woogie on the king of rock and roll!

Just out of curiosity are you guys also compensating the nut end of the fretboard? I've been trimming off about 0.030" (0.75mm) based on discussions here and elsewhere. I use the Stew Mac compensation numbers but subtract the nut end compensation. Like Lars I'm still trying to get a good handle on this.

_________________
Steve Smith
"Music is what feelings sound like"

If you compensate the nut by trimming the nut end of the fretboard .03 short the you must take that off the nut to centerline of saddle at sting position length if measured from the nut. keep in mind that the 12th fret to centerline of saddle at string position stays the same but the nut to 12th fret has shortened by the amount you trimmed off the nut end of fretboard

OK...which is it? I though scale length was high E string location...not center of bridge location like the posted illustration.

I'm currently working on bridge location on a standard 25.4 and a 24.9. Why don't they measure scale length like classical's?
I'll do my layout on posterboard cut to fingerboard..draw in my low and high E string location from nut to saddle. Measure scale length to front of nut on High E string location. Then add a tad for compensation.....or do I just allow the width of the 1/8 saddle to do my compensation. Is that enough?

I work in tads.

Kent Bailey

_________________
Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

Yes, that's what I'm doing. I just subtract the .030" from the high and low E compensated lengths but the effect is to move the centerline of the saddle back .030". Same geometry.

_________________
Steve Smith
"Music is what feelings sound like"