E Slot Syndrome on Nuts

I'm amazed this problem doesn't get more notice, because it's incredibly prevalent.

The builder cuts the nuts or uses a pre-cut nut.

The problem, especially on Fenders, is that the E slot doesn't have a more gradual ramp to compensate for the added stiffness of the big E and the sharp break angle, with the result that the witness point is at the back of the slot rather than at the front of the slot, which causes a fatal intonation problem. The string is just bent over the back of the slot.

So, when the open E is in tune, the first few fretted notes are sharp, decreasingly as you go up the neck. Try it with your guitar. This is not due to a high slot, either.

If you wind the string UP the post, you can sometimes reduce the break angle adequately to solve the problem temporarily.

100% of my new Fenders had this problem, every one of them.

How they never check this at the factory, I dunno.

If you're a builder, how do you cut the E slot to remedy this problem? What angle or curve works best?

Many thanks

So, when the open E is in tune, the first few fretted notes are sharp, decreasingly as you go up the neck. Try it with your guitar. This is not due to a high slot, either.




I would suggest you try that same exact test with your other 5 strings, and you will note that is also true with them. This has been discussed many many times in all sorts of Intonation threads.

I would suggest you try that same exact test with your other 5 strings, and you will note that is also true with them.
I have, and they aren't.
This has been discussed many many times in all sorts of Intonation threads.
Apparently we are talking about a different problem.

There are other reasons why strings are (less significantly) sharp when fretted near the nut. I understand that.

This is WAY worse, and the cause is as I said in the OP. I've proved it conclusively by making it go away by changing the break angle.

.....

I'm not saying you don't have a real situation and have addressed the problem...I was just merely stating that all fretted instruments when intonated perfectly @ the 12th fret, will show sharper results near the nut, and become more accurate as you near the 12th fret (Using an Accurate Strobe)...It's just the nature of a Fretted instrument, even with a Perfectly cut Nut (not as much perhaps)...but still evident.

It sounds like the phenomenon being described here is when a slot is cut with so little angle, that a string breaking over it an a larger angle arcs up above the bottom of the slot before it reaches the front edge.

For example -

http://annarborguitarrepair.com/images/nutslot1.jpg
http://annarborguitarrepair.com/images/nutslot2.jpg

The end result is equivalent to a reverse compensated nut, which will of course cause notable sharpening in the lower frets. This is not that uncommon on factory nuts, which straight from the factory should be considered about as close to completed as a futon is from Ikea.

An ideal slot in my experience should consist of an angle somewhere in the ballpark of around 5° at the face of the nut, with a curved bottom transitioning to just short of the string angle behind the nut as it leaves the back edge. Factory guitars will all need their nuts cut proper after production anyway to set proper height, and shaping the bottom appropriately is just part of this job.

This is not that uncommon on factory nuts, which straight from the factory should be considered about as close to completed as a futon is from Ikea.
Bingo.

The string is only making contact with the back fifth or so of the slot, maximum. I've actually marked the slot surface and checked this.

I see occasionally see burrs on the back of slots for other strings that cause the same symptoms, especially in acetal resin "pre-cut" nuts.

An ideal slot in my experience should consist of an angle somewhere in the ballpark of around 5° at the face of the nut, with a curved bottom transitioning to just short of the string angle behind the nut as it leaves the back edge. Factory guitars will all need their nuts cut proper after production anyway to set proper height, and shaping the bottom appropriately is just part of this job.
Yeah, this sounds exactly like what I had intuitively worked out.

I just wanted conformation from someone who understood the problem and had successfully dealt with it on his bench. I just get blank looks from 95% of the people I've asked about this previously.

Changing the angle in itself won't fix it as the E string simply can't make the sharp bend. This problem is less common on Gibson style "rounded top" nuts as they give a more gradual bend up to the witness point. A curved slot is necessary in a Fender nut.

Thank you for taking the time to read and understand my post and offer a solution!

My tele works fine and the first fret isnt terribly sharp. Not enough to be noticed by ear or in a mix, so I'm not worried about it...

There comes a point where you're too conscious about intonation on a fretted instrument. You're never going to have "perfect intonation and you wouldn't want "perfect intonation" anyways (it would sound like crap). Look at how a piano is tuned. The lower tones are marginally sharp and the higher ones are marginally flat.

You could try fretless, that way you can only blame yourself for intonation problems, not the nut haha

"I just wanted conformation from someone who understood the problem and had successfully dealt with it on his bench. I just get blank looks from 95% of the people I've asked about this previously."

I also shape the slots in a new nut to be sure the string breaks from the front. I discovered this from a G string on a cheap Tele copy that had a second string tree, making for a steep break angle and a flat slot which caused the kind of tuning issues you describe. I've never measured the angle - I just do it till it feels/looks ok and the tuning sounds ok. It seems like it makes the intonation more consistent but I don't have any science to back this up.

I'm amazed this problem doesn't get more notice, because it's incredibly prevalent.

The builder cuts the nuts or uses a pre-cut nut.

The problem, especially on Fenders, is that the E slot doesn't have a more gradual ramp to compensate for the added stiffness of the big E and the sharp break angle, with the result that the witness point is at the back of the slot rather than at the front of the slot, which causes a fatal intonation problem. The string is just bent over the back of the slot.

So, when the open E is in tune, the first few fretted notes are sharp, decreasingly as you go up the neck. Try it with your guitar. This is not due to a high slot, either.

If you wind the string UP the post, you can sometimes reduce the break angle adequately to solve the problem temporarily.

100% of my new Fenders had this problem, every one of them.

How they never check this at the factory, I dunno.

If you're a builder, how do you cut the E slot to remedy this problem? What angle or curve works best?

Many thanks

I am of the opinion, that this is not a problem on a properly cut nut, but factory production guitars almost never have a properly cut nut.

When I cut my nuts, I use a process similiar to Dave's. Once I started incorporating properly cut nuts into my guitars, I was amazed at how much better they played and sounded.

Look at how a piano is tuned. The lower tones are marginally sharp and the higher ones are marginally flat.

This is just plain incorrect. A piano is tuned using stretch tuning where middle C (C4) is tuned correctly and the octaves above C4 are tuned progressively sharper and the octaves below are tuned progressively flatter. The deviation is as much as 18 cents in each direction so the total can be 36-ish cents between C1 and C8. It is, however, relative to the instrument (upright or grand) due to the the string length and tension that comes with those different styles of construction. The deviation also varies between lower and higher octaves with the lower ones getting less "stretch" than higher ones.

Re: the OP comments - as has been stated - I wish this was the only problem to be found with string nuts from FMIC. They are generally very bad with many of them needing repair/replacement straight out of the box.

is that STILL bugging you??!!!???:mrgreen: