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I finally strung up El Kabong, my first stab in acoustic guitar making. Strings 1-3 intonate fine. Strings 4-6 are all sharp at the 12th fret. Where do I go from here?

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Julie Moriarty
http://JulimorCreations.com

How sharp? Acoustic guitars rarely intonate perfectly. An intonated saddle may help or you may need to move the saddle slot, depends how far off...

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

https://www.youtube.com/watch?v=EJG5Frbu78c
most times people do the nut to 12 th fret times 2 that doesn't work. The point is the bridge will settle in. now if your sharp you can work your saddle back a bit to help lengthen the string length.
I prefer to set this up a touch long so that the stings on initial set up are about 2 cents flat. The reason is that your guitar top will allow the bridge to rotate. If you don't plan for this you may have a difficult getting the best intonation out of the guitar.
so plan that the saddle will have room for this movement. Martins use a 3/32 I like to use .1 and plan my layout scale length plus .1 in to the middle of the saddle using ,100 saddle. This affords me great adjustment after about 3 months . Also if you think about it you always will pull sharp never flat
then to add to the confusion you can also set the nut up for compensation. To help people grasp these concepts take a board and set up a fretboard and saddle and you can move up and down. Using a tailpiece is perfect. At the nut you can taper the nut say about 1/32 from 1 to 6 string. Now play with the positions of the saddle and the harmonics of the string , and fret placment. You will learn a great deal that you can apply to your building by doing this.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Things to do, now that the bridge is glued on and you need to fix intonation on the bass strings, in increasing levels of hassle:

1. Try setting the fulcrum point for the bass strings at the back of the saddle.

2. Make the slot wider in the back and use a thicker saddle, then use 1. above.

3. Fill and re-slot the bridge, this time using something like the StewMac Intonator to find the right slot position before you rout it.

sharp go back so as Brian said how sharp?
as for the stew mac thing my best advice is get a good scale . I have repaired too many saddles that used the saddle matic. Learn the physics your better off.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I was talking about the Intonator, not the Saddlematic, John. The Intonator fits on an unslotted bridge and helps you figure out where to cut the slot based on actual intonation.

Wait... what is wrong with the saddlematic and standard compensation?

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Why not just use Stewmacs fret calculator. It’s free on their site, look for the tab at the bottom of their homepage. Gives you every dimension you need for fret slots and saddle position based on a specific scale length.

Good question....

...and for those that don't remember or weren't around...

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

I don't find anything wrong with it at all. But, like any tool that can be adjusted, it can also be maladjusted, which will give a bad result. Maybe John's repair clients didn't use the tool the right way. That's what I suspect. When I use it as intended, it works fine. But I do verify saddle location via several different methods, to make sure I am not messing up.

There are several ways of getting to the right result during building, and I am sure Jules will benefit from what everyone is saying about those methods, but the situation as it stands right now is that the bridge is on the guitar, the saddle slot is routed, and it is probably in the wrong spot. This calls for a repair.

OK, just wanted to make sure there wasn't some downside I wasn't aware of. FWIW, I made two small shims that are the right thickness for compensation. They set the pins correctly very reliably. I haven't had any issues with intonation so far.

Will be good to hear how sharp exactly and if the low 3 strings are already all the way to the back of the saddle.

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yes the adjustable thing is ok but learn the physics
here is why I find the stew mac thing a bit off
A you make an assumption at a perfect application.
B You may assume all fret boards are the same
So once you learn the true physics you see that you can rely on a measure scale more reliably. Each guitar should be set up for an individual player. Different players require a different set of parameters . So for sake of discussion we will take 2 ends of the scale a finger picker and a bluegrass picker.

so you need to know and understand the variables that apply for each application.
variables
A string gauge
B action height
C top movement
D neck relief
E humidity
F players style

so how do these apply ? The higher the action the more you will pull a string sharp.
So if you adjust compensation and intonation as a 2 1/2 3 1/2 action and a .004 relief
that is fine but if your RH conditions change the action will rise and you will start going sharp.

a finger picker will most likely like a softer action and will not want high action , so his parameter will be different than a hard picker blue grasser.

Keep this in mind as you learn how these variable effect each other. That is why I suggested you make a compensation board. You can see how all this works together. I have learned not to rely on these jigs and fixtures as they can give you false security. There is no one answer for all guitars. As a builder you need to know your customer and make the set up to what will fit that players style.

I only been doing this for 20 yrs and have learned a thing or two. You don't have to agree with me but do take the time to learn each variable and the cause and effect it can have.
You never will play a guitar and influence flat in the real world you will always tend to pull sharp after all the fretting technique pushes the string and thus changes the tension. You never take tension off when you play you add to it so this is one variable you need to understand when accessing a players style.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Thanks, John. Good stuff.


Sent from my iPhone using Tapatalk Pro

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The Stew-Mac Intonator setups up compensation with string tension in effect. Eliminates that variable.

I have only been doing this for 44 years so I feel I have a lot to learn ;-)

On an electronic tuner, it hits between 2 & 3 o'clock. 12 o'clock being perfect.

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Julie Moriarty
http://JulimorCreations.com

If you don't have a piezo pickup under the saddle, and the bridge pins are far enough back to allow it, you make a two piece saddle. You might be able to just cut the slot further back for the problem strings and put some shims in the front part of the slot. You might have to glue some new wood in to be able to carve a slot into. To find out how far back you need to go, the stewmac gadget is fine, but I've been able to get the same thing accomplished slower by finding scraps of metal or carving hardwood splinters that I can set on the bridge (with the saddle removed) so that I can tighten the string to pitch, have the action at the correct height, and listen to the results of moving the string take-off point back.

I play a lot of finger picking stuff up the neck, and it sure is nice to get the intonation a little better than most acoustic guitar players expect.