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Old 06-30-2018, 10:24 PM
rodmbds rodmbds is offline
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Default Low string height at nut

Hi there! This weekend I decided to substitute my guitar's plastic nut and saddle for bone. I've made two sets, one for high action and the other for low, thinking I'd test both and decide by feel.

At the 12th fret, high action measured 4mm bass E and 3.5mm treble e. Low action is at 3.5 and 2.7, no buzzing unless I really dig in.

The high action nut has a lot of space to the 1st fret when pressing the string at the 3rd fret and feeling it. It's high but fine, playable.

The low action nut, well... Got carried away and filed more than I initially intended. There's a gap there, between the string and 1st fret (again, pressing at the 3rd). It's a really really small gap, gosh, the high e barely fits a sheet of paper.

When strings are not pressed, of course there's a bigger gap, the strings are not touching the 1st fret nor buzzing when open string is played.

The strings don't vibrate so much at the 1st fret, I guess it's ok. The guitar now plays like a dream, no buzzing!

Question is, next time I cut a new nut for a guitar, should I keep using the "press 3rd fret and measure gap at the 1st" or should I just keep strings open and lower the slot until the string is a bit over the 1st fret, open?

To rephrase that... I sort of made a mistake and got a really great low action at the nut without buzzing. I'd never, intentionally, got that low on the slots, nor have I seen other people recommending that.

It reminded me of an electric guitar which I also filed the nut slot too much, there was no gap at the 1st when pressed at the 3rd. But when open, the string didn't touch the 1st nor did it buzz. Totally against recommended but it worked.
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Old 07-01-2018, 04:26 AM
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srick srick is offline
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Rod - I think many of us who have gotten that first set of nut files have been in the same situation. A thin piece of paper is .004 - so that’s the tolerance that you are working with. And there are variables all over the place on any guitar: glue in the slot, not perfectly cut slots, perfectly cut nut slot on one string and not the other, etc. etc.

So here’s a get out of jail free card courtesy of Frank Ford: if you cut a nut too low, get a self-adhesive address label and stick it on the bottom of the nut. Then, trim to size, and voila! Believe it or not, there is minimal\no discernible effect on the tone of the guitar.

Learning how to adjust and cut a nut is probably one of the more important tweaks the amateur luthier should know. It has the most immediate influence on the perception of how a guitar feels. And, if you like how the instrument feels, you will likely play better.

Now put your credit card back into the wallet and stop thumbing through the Stew Mac catalog!

Best,

Rick
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Old 07-01-2018, 06:39 AM
rodmbds rodmbds is offline
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Thanks for taking the time to answer, Rick!

Yep, I knew about this label thing from Frank Ford, I actually learned it here at the agf. I've used it before in other guitars and didn't feel a difference in tone. I understand that over time the strings wear down the slots (don't know if the treble strings really do) and that's a neat way of slightly raising the action.

You're right, many variables involved. But I guess this tolerance of a piece of paper is acceptable then, as the guitar is not buzzing.

I've always tried to leave a moderate gap because, being nylon strings, there's more tendency to buzz.

But now the string height at the nut is basically setup just like a steel string or an electric guitar. It gets me wondering if nylon strings really need that much of a gap at the nut.

Btw, I forgot to mention that the strings I'm using are Daddario's Pro Arte Normal Tension.

PS: thanks for the advice Rick, but I don't order from Stewmac nor do I have a credit card I don't live in the US and buying imports here is really out of question because of taxes (it'd get about two or three or times more expensive just because of them).
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Old 07-01-2018, 06:48 AM
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Quote:
Originally Posted by rodmbds View Post
PS: thanks for the advice Rick, but I don't order from Stewmac nor do I have a credit card I don't live in the US and buying imports here is really out of question because of taxes (it'd get about two or three or times more expensive just because of them).
This is a very good thing, Rod! stewmac creates the neatest luthiers gadgets to make your life easier, and yet luthiers have gotten by without them for years! You’ve got to admire a company that finds solutions for problems you never knew you had. I really do love looking through their catalog and watching their videos.
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Old 07-01-2018, 06:53 AM
rodmbds rodmbds is offline
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Quote:
Originally Posted by srick View Post
You’ve got to admire a company that finds solutions for problems you never knew you had.
So true and there are many out there.

I also love watching their videos. But again, gets me trying to fix something that is not broken. Though they're great videos, I've learned more about "everyday repair" here at the agf.
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Old 07-01-2018, 07:53 AM
Tim Mullin Tim Mullin is offline
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Default Low string height at nut

I build and repair professionally, including classicals. A few comments on your setup attempt.
Your “low action” spec would be my target on most instruments, unless they have inadequate neck relief. Having said that, I have professional clients who prefer the more traditional high action setup. Since you make no mention of relief, I assume your guitar doesn’t have an adjustable truss rod.
Regardless of 12-th fret string height, there is no need to set up nuts with different slot depth. The objective when filing slots is ALWAYS to match the leading edge of the slot bottom to the fret plane, as if your nut was a “zero” fret. Pressing the string between the 2nd and 3rd fret, the gap between the string and 1st fret should be the same as if you were to capo at the 1st fret, press between 3rd and 4th and measure the gap at the 2nd. Does that make the target more clear? The gap should be very small, 0.05 - 0.1 mm, provided the neck had at least some relief. Only when a guitar has no relief at all would I exceed 0.1 mm.
Nut slot depth and neck relief adjustments (if possible) are made independently from 12th fret string height. Set those BEFORE you adjust your saddle to give you the action height you want.
Hope that’s helpful.
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Old 07-01-2018, 10:59 AM
rodmbds rodmbds is offline
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Quote:
Originally Posted by Tim Mullin View Post
I build and repair professionally, including classicals. A few comments on your setup attempt.
Your “low action” spec would be my target on most instruments, unless they have inadequate neck relief. Having said that, I have professional clients who prefer the more traditional high action setup. Since you make no mention of relief, I assume your guitar doesn’t have an adjustable truss rod.
Regardless of 12-th fret string height, there is no need to set up nuts with different slot depth. The objective when filing slots is ALWAYS to match the leading edge of the slot bottom to the fret plane, as if your nut was a “zero” fret. Pressing the string between the 2nd and 3rd fret, the gap between the string and 1st fret should be the same as if you were to capo at the 1st fret, press between 3rd and 4th and measure the gap at the 2nd. Does that make the target more clear? The gap should be very small, 0.05 - 0.1 mm, provided the neck had at least some relief. Only when a guitar has no relief at all would I exceed 0.1 mm.
Nut slot depth and neck relief adjustments (if possible) are made independently from 12th fret string height. Set those BEFORE you adjust your saddle to give you the action height you want.
Hope that’s helpful.
Very helpful, thanks indeed! When I get to my guitar I'll measure as you said.

Yes, I forgot to mention truss rod, there isn't one. There's a slight bow which gives it some relief.

I always went for high action being afraid of buzzing in open strings. I was amazed by my "mistake" and managing to get low action at the nut unintentionally.
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Old 07-01-2018, 11:09 AM
rodmbds rodmbds is offline
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Tim, you mentioned to adjust nut and relief before saddle height, right? It got me thinking.

If I have a high saddle, adjust relief (not the case in my guitar), nut and then lower the saddle, wouldn't that affect the nut as well? I mean, wouldn't the strings, even if little, get lower at the nut too?
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Old 07-01-2018, 12:22 PM
bausin bausin is offline
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>> wouldn't that affect the nut as well?

Of course it would. But do a little basic math and see how little effect a change at the saddle has on the nut.
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Old 07-01-2018, 02:09 PM
rodmbds rodmbds is offline
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Always thought it was the opposite, first the saddle and then the nut.

I liked the idea of using the capo and use that gap as a reference to cut the nut slots.

So, at the nut, there wouldn't much difference in the gap from the top of the fret to the bottom of the string between nylon, steel and electric guitars?
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Old 07-01-2018, 04:47 PM
Tim Mullin Tim Mullin is offline
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Quote:
Originally Posted by rodmbds View Post
If I have a high saddle, adjust relief (not the case in my guitar), nut and then lower the saddle, wouldn't that affect the nut as well? I mean, wouldn't the strings, even if little, get lower at the nut too?
They would be lower over the first fret, yes, but nothing you do at the saddle affects the plane of the frets, and the nut is nothing more than a zero fret. Setting the slot height properly is independent of relief, string height or instrument type. Assuming (BIG assumption!) that the frets are properly levelled, the ideal slot depth is the same. It is only when adequate relief can’t be set or some other fret plane issue that one might be tempted to raise the nut slot.
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Old 07-01-2018, 04:50 PM
Tim Mullin Tim Mullin is offline
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Quote:
Originally Posted by rodmbds View Post
Always thought it was the opposite, first the saddle and then the nut.
?
No, never.
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Old 07-01-2018, 04:56 PM
Tim Mullin Tim Mullin is offline
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Default Low string height at nut

Quote:
Originally Posted by rodmbds View Post
So, at the nut, there wouldn't much difference in the gap from the top of the fret to the bottom of the string between nylon, steel and electric guitars?
With a properly levelled fret plane, the ideal nut slot height is defined by the fret plane, regardless of instrument or string type.

Now, there will be differences of opinion among luthiers. In fact, what I’ve written is not what I was originally taught! But, my first career was as a scientist, and I’ve given this a LOT of thought. Happy to argue the logic with any luthier out there. I know many well respected luthiers who follow this approach and logic 100% — just not all of them.
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Last edited by Tim Mullin; 07-01-2018 at 05:10 PM.
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Old 07-01-2018, 05:41 PM
bausin bausin is offline
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Tim,

When you're done convincing them (luthiers) about proper nut slots, could you convince them that strings don't vibrate in an elliptical pattern?
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Old 07-01-2018, 07:34 PM
Rodger Knox Rodger Knox is offline
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I agree with Mr. Mullin, and that's the sequence I use. It is possible to do the relief first, saddle next, and save the nut slots for last. After the relief is adjusted, the first fret is capoed to set the saddle height. That eliminates the effect of the nut slots while setting the saddle. That method has been published in Guitarmaker magazine, so it does work.
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