Official Luthiers Forum!

Hey all!

First time post here. I tried doing a couple searches before posting but wasn’t quite finding what I’m looking for, probably user error.

I just finished my first acoustic guitar build. The instrument is a 000 Martin kit I bought from a guy who quickly discovered he is in over his head. At the point of starting, I had built 3 other electric guitars from scratch and wanted to try an acoustic. I encountered plenty of problems that I was able to intuitively overcome but now I’m at the finish line and could use some advice.

I strung up the instrument and I’m finding that my b string is having intonation issues. All the other strings seem spot on when fretting open and at the teeth fret. The b string plays pretty sharp when fretted at the 12th fret.

I’ve never made any intonation adjustments on an acoustic instrument and looking for advice.

Other background of note. For this instrument I also made the nut, which was also a first time endeavor. I’m sure I did something wrong there. I also shaped the saddle for the first time. The action is where I like it on frets 1-5 with just a little relief in the neck. There’s room to bring the saddle down if necessary.

Where would you guys lol first?

Can you post a photo of the saddle so we can see how it's shaped for intonation? That would help with suggesting how to proceed.

The breakpoint for the B string on the saddle typically needs to be further toward the back edge of the saddle than the breakpoints for the G and high E strings to get the correct intonation.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

To help the people who would like to help you, there are a few things you should do:

1. Say what gauge strings you are trying to use.
2. Post a few photos of the strung up guitar, focusing on close ups of the nut, the saddle, and the fingerboard overall. Side views show more of what folks are going to want to see. Front views don't provide much information.

In general, a lot of folks who are cutting their first (or first few) nuts leave the slots for the strings at the nut too high, and the string that will be the worst off (intonation-wise) from that problem is the B string. If you combine a too-high nut slot with a saddle that is set too high, it is common for the B string to intonate too sharp. I'm not diagnosing your problem; I'm just playing the odds that you are making a common mistake, and it has resulted in a common symptom from that type of mistake.

Here's a typical saddle showing compensation for the b string. Hope this helps.

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formerly known around here as burbank
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http://www.patfosterguitars.com

Correct intonation is a function of:

1) A properly made and cut nut with the nut slots cut very low so as to not pull strings sharp when fretted

2) Good fret work and a fret plane that is level, has minimal relief on the treble side and more relief on the bass side

3) Action for an OOO sized guitar when the truss rod is adjusted as described in no.2 at the 12th fret of 4/64th" for the high e and 5.5/64th" for the low e with the guitar tuned to pitch

4) Then it's adjust the action at the saddle and check the intonation and adjust accordingly. On an acoustic of course we can't twist screw drivers unless it's a vintage Gibson with a hardware store for a bridge on it. But with an acoustic at this point we can measure the intonation and compare to what we have. A well made acoustic saddle has the break points with the high e forward of the b, the g forward of the b and the rest slightly aft of it's neighbors.

So my approach would be to go though all of the above and then measure, note/write down and make the final saddle with the break points for each string as per the data I gleaned here.

Hope this helps.

Nice Pat.

If I may please add when you know what the set-back saddle pattern is you can make a saddle that looks like this and if all the other things in my post are correct it will intonate well provided that the saddle slot is properly located and there are no defective strings in the pack. Always use new strings to set intonation and always use the strings the client uses to set intonation because different string brands intonate differently even for the same gage of string.

Thanks for all the advice already! I stopped at the local music store on my way home to look at some saddles and nuts on retail instruments. What I Immediately noticed, which somehow I never did before, was they all have some extreme shaping for the B string. On both machined saddles and carved saddles, the break point was nearest the back of the bridge, much more so than for any other string. The one I made is basically just round on top all the way across.

Someone else asked about string gauge. The kit came with some 13’s which I find to be much heavier than I like. I picked up a set of 12s while at the store.

Lastly, I’m having trouble uploading pictures from my phone. When I use the attach feature, it tells me my files are to big, even if I use the websites prompt to take a picture. Is there a different method for uploading pictures here?

Thanks

You may have already seen this method for determining the intonation points on a saddle, but just in case you might not have.

With the top surface of the saddle blank radiused (but still flat front to back), the saddle height set for the action you want, and the guitar tuned to pitch, you detune one of the strings and slide a leftover piece of B string under that string to serve as a contact point on the saddle. Tune the string back up to pitch and check the intonation. If the intonation is off, detune the string and move the position of the B string piece forward or backward as needed and tune back up to pitch and check the intonation. Repeat as needed until the intonation is correct. Then mark the position of the B string piece as in the photo below and move on to determining the correct breakpoints for each of the other strings.




When you've done all the strings, the saddle will look something like below. The centers of the marks are where you want the breakpoints to be.




The saddle in the photo Pat posted above in the thread shows one way to handle the B string breakpoint. I do mine like below. There probably are other ways to do it too.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

You can upload bigger pictures using taptalk which will resize automatically, or just use paint with your PC to resize them. (Just save your file after resizing)

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Here are the pictures. As I stated, my saddle is just round with no compensation. I have some more work to do it sounds like.
Thanks everyone


Sent from my iPhone using Tapatalk

In the fixture sub-forum, there is a nut making post created by our friend Hesh.
It was a game changer for me, and well worth studying.

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wah
Wah-wah-wah-wah
Wah

Matt - I can see from your photos that the action at the nut is higher than a cat's back. THAT is most likely the strongest source of your intonation problem. If the nut slots are too high, the guitar will never play in tune because you are sharping the string at both ends when you fret it.

If you don't have any of the proper tools to lower those slots, please find a competent and experienced luthier in your area to do this for you. You will NOT find anyone like that at Guitar Center, okay?

If you desire to do the work, be prepared to buy the correct tools and learn what to do here on the OLF. We'll be glad to help you. BTW - welcome!

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"Act your age, not your shoe size" - Prince

Yes, Chris is right, and my guess from yesterday (above) was right. Your biggest culprit is the nut. You've gotta cut the slots lower.

You can ramp the saddle if you want, but there's not much that ramping can accomplish on a saddle of that width. It's more of a minor tweak than anything. In contrast, the nut slots are far too tall. Assuming the bridge is in the right place, your intonation issues are mostly nut issues, not so much saddle issues.

Thanks guys. For the tools, I do have nut slotting files. I also have the safety nut slot guard from stewmac. I also noticed when I took the pictures that my nut isn’t sitting level on the neck. I should probably fix that too.

Yeah, I wasn't sure, but the first of your nut photos looks like it shows an "air gap" under the nut. You can't have that. In fact, forget about the nut slots until you get the nut to fit solidly into the space between the end of the fingerboard and the headstock veneer, and sit flush against the neck in that gap. In other words, sand the width of the nut until it "bottoms out" in that gap.
That's got to be done first. Then you can reassess the depth of the slots. There's lots of guidance about how to do that. But you really need to get the nut to fit in the gap first.

Try to take good care when working on the nut slot; it's easy to make a mess of it, and it's right in front of
the player to see.

Love what I am seeing here, very nice work J!!!!

I would suggest that with each subsequent guitar build we all get better and eventually address more and more things.

This forum is dominated by woodworkers who want to build guitars so you will find more discussions about band saws than making a proper nut and that's where I have tried to add value over the years, the set-up stuff that you have a couple days of work to complete the instrument with, fretting, nuts, saddles, intonation, action, relief etc.

My first guitar was so bad the trash man even didn't want it. But we got better so no worries you will get there and everything that you have to chase down such as that B string intonation will make an impression on you that you will likely retain for the rest of your days.

Lastly and I am reluctant to overwhelm you with information cutting nut slots is an art and it can take years to get good at it. I do dozens and dozens a week so I was baptized by fire and get nut slots pretty well these days.

My business partner was a professional Luthier instructor at the Galloup school and a Luthier at Elderly before I met him. He says it takes about 100 nuts to start, start to get good at making them and I agree. So everything in time and the next step is to complete this one and then move on with what you have learned and do much better next time and I am sure that you will. Let me know if I can help.

I’ll add that if you put a capo on the first fret, you can check intonation without the effect of the nut slot heights.

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wah
Wah-wah-wah-wah
Wah

Yeah I have done that and it’s not perfect but definitely plays more in tune with a capo

That is called a clue. Rework those nut slots!

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"Act your age, not your shoe size" - Prince

I’ll add something to consider as well, when considering the nut
Make sure that your nut has a break point at the font of the nut it looks …. Maybe…. Like your slots may be rounded so that the breakpoint is back away from the front.
You want your slot angled at about the angle of the headstock (probably 15 degrees ish)


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I’ll offer one slight variation from what Snow just recommended. When you are cutting nut slots, you are doing it by hand. That means you can’t keep a perfect angle all the time. If you are trying to keep an angle that matches the headstock angle, you are going to go a little bit over that angle on some strokes, and a little bit under on other strokes. Having the slot at that large of an angle, with the inevitable variance, could cause some buzzing as the string enters the slot from the tuning machine, because the slot could be lower than the path of the string from the tuning post. I think it is better to shoot for a nut slot angle that is roughly half of the headstock angle. That way, even if (when) the slot is a bit curved front to back, the string will make solid contact all along the bottom of the slot. There’s less chance of buzzing. That’s my way of doing it. YMMV.

I made a new nut today and it’s already sounding so much better. I followed Hesh’s post for making a nut and it worked great. My action around the 7th fret and up is still a little high, but I haven’t done anything to the saddle or truss rod so I still have a few levers to pull on.

Thank you everyone for all the advice and suggestions!

Good going Matt!! Now measure the action at the 12th, that's the industry standard and then we Loofiers are all speaking the same language. It's at the 12th fret that we want the action numbers provided provided that the truss rod is set correctly and the nut slots are cut low enough but not too low. You will know when you gut a nut slot too low it has a sitar sound that sounds like it is coming from the bridge even though it's not.