Setting up an old Cort acoustic. Running into issues.

[Gil80]

Hi all.

I'm new here.
Thanks for allowing me to join your community.

I own a cheap Cort guitar and I decided to try and fix its intonation and action highet.
I was hoping to get some help here if anyone knows about this thing and may have some experience.

Truss Rod
I bought a new bone saddle and nut.
I adjusted the truss rod to be exactly how I wanted it, having a hair's width of a gap between the low E string bottom to the top of the 6th fret.

Action and Saddle
I like low action. I sanded the saddle to the point where the low E on the 12th fret is 2mm and the high E is 1.5mm on the 12th fret.
Measurements of before and after were taken with a Capo on the 1st fret (on the actual fret).

I did measure the the 1st fret action and it was 0.5mm for the low E and about 0.25mm for the high E.
But I cared less for 1st fret action at this stage.

Intonation and Action
The problem I’m facing with intonation is the low E, A and D strings.
They are too sharp when checking the overtone on the 12th fret with the fretted note on the 12th fret.

The saddle cannot be moved back than it already is. I’m only left with the nut to try and increase the strings length. However, I cannot seem to change the nut takeoff point of the low E without introducing string buzz.

The biggest problem I've seen with this guitar is that the strings are buried in their nut grooves.
So step 1 was to use the superglue + baking soda technique to fill in the low E nut channel and then sand it down so only half of the diameter of the low E is buried in the nut (using graphite to "oil" the channel).
This helped to place the low E intonation "dead on" (using Boss chromatic tuner to check)!

So what's the problem?
This actually increased the action hight on the 1st fret and feels like it's a bit harder to press down.
I have to repeat this process for the A and D strings as well.

1. If I sand the saddle further than it currently is, will that take it out of intonation again?
   
2. Is there a way to get the intonation and action without compromising on either of them?

* I would compromise on intonation a bit, in order to have better playability.

Any help and guidance is appreciated. I'm very new to this and probably have done many mistakes in my explanation and approach, so feel free to call me out if I approached the problem incorrectly.

Thank you!

[Brucebubs]

Welcome to the AGF.

Is the new bone saddle compensated .. something like this diagram?



The basic rule is;

If the string notes SHARP move the saddle BACK - INCREASE string length

If the string notes FLAT move the saddle FORWARD - DECREASE string length.

[Gil80]

Originally Posted by Brucebubs

Welcome to the AGF.

Is the new bone saddle compensated .. something like this diagram?



The basic rule is;

If the string notes SHARP move the saddle BACK - INCREASE string length

If the string notes FLAT move the saddle FORWARD - DECREASE string length.

Hi and thanks for your reply.

Yes, the saddle is fully compensated, i.e., it's exactly as in the photo.
the high E and B are perfect.
The low E is at a point where I cannot move it further to the back. If I could, I would pivot the saddle so the low E is moved backward, but then it would be too close to the string hole and I don't want to mess with the bridge as I don't have the proper tools for the job.

Seems like I'm only left with the nut to do the trick.

By the way, when I purchased the new saddle and nut, I then realised how much my original nut has too deep grooves when comparing with the new nut.

Lastly, referring to the basic rules you kindly provided, increasing the hight of the low E nut slot (groove, slot, channel, how do you call it?), seemed to lengthen the string, thus allowing correct intonation.

[charles Tauber]

As you've pointed out, at either the nut or the saddle, one can effect changes to the actual vibrating string length by moving the breaking point of a string. Each has a different effect on the intonation.

If you have the string break over the nut at the theoretical zero point and then measured how many cents each note of that string is out, as you progress up the frets, then graphed those points, with cents along the Y axis and fret number along the X axis, you'd have a straight line that best fits through those points.

The line will intersect the Y axis at some positive value (some number of cents) and, typically, each fret will be more out of tune than the last, producing a line at some slope.

By moving the breaking point of the string over the nut to make the distance from breaking point to frets longer, you lower where that line intersects the Y axis. The result of increasing the string length at the nut is to uniformly decrease the deviation of all the notes (frets).

By moving the breaking point of the string over the nut to make the string longer, you change the slope of that line. The result of increasing the string length at the saddle is to, ideally, obtain a uniform amount by which the pitch at each fret is out (i.e. to have a zero slope.)

The increase in string length (compensation) at the nut reduces the amount of compensation required at the saddle.

If you are going to go at it from both ends of the string, you really need to map the deviation at all of the frets, rather than just the deviation at the 12th fret. Also, you'll get better results if you compare the pitch of the open string to its octave, the fretted note at the 12th fret. That keeps the open string in the equation.

Having the string height at the nut too high negatively affects the intonation in the first few frets. How deep the nut slots are has no bearing on the intonation. While a rule of thumb is 1/2 the diameter of the string in the slot, there is no harm it having the slot deeper. What matters is that the string height at the nut is correct, not how deep the slot, itself, is.

[DenverSteve]

Because of the questions you are asking, and what you've already done, I would take the guitar to a good set up person and have a great set up done. The first thing I read that gave me an oh-my moment was that you set the neck relief "how you wanted it" and not necessarily where it needs to be for a great set up.

[Gil80]

Originally Posted by DenverSteve

Because of the questions you are asking, and what you've already done, I would take the guitar to a good set up person and have a great set up done. The first thing I read that gave me an oh-my moment was that you set the neck relief "how you wanted it" and not necessarily where it needs to be for a great set up.

Yeah, I can understand how this came across
Trying not to "defend" myself here, but what I really meant was, I took measurements before adjusting the truss rod by placing a capo on the 1st fret and pressing the fret at the start of the body (I believe it was 14th fret).

I measured each string along the neck. I have found that the 6th fret on each string had the highest gap (too much relief).
I adjusted with 1/8th turns of the truss rod and re-measured until the relief was about a width of a hair and no string buzz along the neck.

That is "how I wanted it"

[Gil80]

Originally Posted by charles Tauber

If you are going to go at it from both ends of the string, you really need to map the deviation at all of the frets, rather than just the deviation at the 12th fret. Also, you'll get better results if you compare the pitch of the open string to its octave, the fretted note at the 12th fret. That keeps the open string in the equation.

I'm not in a position to go at it from both ends since the saddle is fully compensated. Any changes to it will be so minor that I won't hear the difference. The high E and B are spot on, it's the bassier strings that are the issue and the saddle is already compensated for them.

Originally Posted by charles Tauber

Having the string height at the nut too high negatively affects the intonation in the first few frets. How deep the nut slots are has no bearing on the intonation. While a rule of thumb is 1/2 the diameter of the string in the slot, there is no harm it having the slot deeper. What matters is that the string height at the nut is correct, not how deep the slot, itself, is.

Interesting. I understand that too high negatively affects the intonation, so how come when I've re-done the low E slot (made it a bit higher and changed its slope) resulted in correct intonation?

When I check for intonation, I check the open string, the overtone at the 12th fret and a fretted note at the 12th fret.
I didn't check the entire neck though. Assuming that if the 12th fret is in tune, then the deviation across the lower parts of the neck are not noticeable.
However, I might be wrong as I'm new to this

Is this a good "low action" to target for at the 1st fret.
Low E: 0.51mm (0.020”)
High E: 0.30mm (0.012”)

[Brucebubs]

Originally Posted by Gil80

Is this a good "low action" to target for?
Low E: 0.51mm (0.020”)
High E: 0.30mm (0.012”)

Not sure how you're measuring - I place a ruler (which reads from the edge) right on the 12th fret - behind the string like this.



Here I read the string height as just over 2.0mm but not more than 2.5mm.

[Gil80]

Originally Posted by Brucebubs

Not sure how you're measuring - I place a ruler (which reads from the edge) right on the 12th fret - behind the string like this.



Here I read the string height as just over 2.0mm but not more than 2.5mm.

I'm measuring like you do, from the bottom of the string to the top of the fret, using this

[charles Tauber]

Originally Posted by Gil80

I'm not in a position to go at it from both ends since the saddle is fully compensated.

From your description, you already have. The saddle is already compensated and now you are compensating the nut. That is, changing the string length from both ends.

it's the bassier strings that are the issue and the saddle is already compensated for them.

I understood that from your OP.

The saddle probably isn't (fully) compensated for them, that's (largely) why they sound sharp. ONE approach is to add more compensation at the saddle. You've stated there isn't anymore room to do that with the existing saddle and pins. USUALLY, that is what is done and usually provides adequate compensation for the range of the instrument, if done properly/fully.

Compensation at the nut is done in relatively few cases and for the specific reasons that I mentioned. Some want the improved intonation that compensation at both nut and saddle provides. Most don't find they need it.

Interesting. I understand that too high negatively affects the intonation, so how come when I've re-done the low E slot (made it a bit higher and changed its slope) resulted in correct intonation?

No idea. Likely something else is also going on.

Assuming that if the 12th fret is in tune, then the deviation across the lower parts of the neck are not noticeable.

That is what is most often done. However, it ensures that the intonation is correct only for the 12th fret. Doing so, it is often less accurate above and below the 12th fret.

Is this a good "low action" to target for?
Low E: 0.51mm (0.020”)
High E: 0.30mm (0.012”)

For what measure? The string height at the 12th fret? That is too low for that.

Photographs of what you have at both nut and saddle would help greatly.

[Gil80]

Originally Posted by charles Tauber

From your description, you already have. The saddle is already compensated and now you are compensating the nut. That is, changing the string length from both ends.



I understood that from your OP.

The saddle probably isn't (fully) compensated for them, that's (largely) why they sound sharp. ONE approach is to add more compensation at the saddle. You've stated there isn't anymore room to do that with the existing saddle and pins. USUALLY, that is what is done and usually provides adequate compensation for the range of the instrument, if done properly/fully.

Ok, I understand now. I bought this saddle as fully compensated. That is why I referred to only compensating the nut. But you are correct, the compensation is done on both ends. Thanks for correcting me.
I think the saddle groove on the low (bass) strings should be a bit further back towards the pins. I most certainly cannot sand in more without making the contact point too sharp for the string touch point.

Originally Posted by charles Tauber

For what measure? The string height at the 12th fret? That is too low for that.

Photographs of what you have at both nut and saddle would help greatly.

Sorry for not addressing it in my post.
It's for the string height at the 1st fret.

[Gil80]

I created a public album with photos I took of the nut and the saddle and my notes.
The nut is not polished, but the slots are polished and used with graphite. It's not a clean job, but the point is to get the measurements 1st, before cleaning the mess.

Album: https://ibb.co/album/nC3s1F




So leaving intonation aside for now, just looking at what I can do the make the 1st fret action reach my target (listed in my notes) is my current challenge.

In addition, the G string created a groove on the saddle. Should I sand it and make a wider base for the G string to rest upon?

Also G string (and not the good kind), on the nut I did a mistake and you can see in my photos that it is not resting properly and this results in tuning issues.

Ignore the colours of the strings for now. I'm using a mix of brands but they are all the same diameter. After getting the correct action on 12th and 1st frets, I'll swap to a single brand and focus on intonation.

Thanks for any help!

[charles Tauber]

Looking at the photos, a few observations.

1. you have very little break angle of the strings over the saddle. Try having more than one winding around the tuning machine posts and have the strings wrap progressively towards the bottom. Doing so increases the break angle over the saddle.

2. It is difficult to tell from the photos, but the slots don't look very "clean", as in well-defined. The slots need to be well defined, with well defined breaking points for the strings. If not, you run the risk of intonation issues, buzzing, etc.

3. I don't use the string height above the first fret as a measure. Many people do, but I'm not one of them. Different people have different ways of accomplishing various tasks. The method that I've settled on for nut slots is to use feeler gauges stacked to the desired height adjacent to the face of the nut. You then file until you just touch the top of the feeler gauges with the file. (You can feel when it touches.) It's a method that works for me and takes any trial and error out of the process. Using this method, I'm filing the thing I'm measuring- I'm directly effecting the thing I'm measuring - rather than indirectly filing one thing to achieve a derived result elsewhere (i.e. string height above the first fret). The desired height of the strings at the nut is, theoretically, the same height as the first fret/plane of the frets. Practically, I'll add 3 to 8 thousandths of an inch to that, depending upon the instrument and the specifics of how it is played. Others fret between the 2nd and 3rd frets and look for a minimum gap of the string above the first fret - a "qualitative" approach. Luthier supply houses also sell digital height gauges that allow one to obtain qualitative measurements of the string height above the first fret. Tried that, didn't like it, but it works as well.

4. as you stated, there isn't any further saddle thickness to add more compensation for the low E. Both the A and D strings still have room for additional compensation, probably enough to fully compensate those two strings.

5. One can buy a commercially made "shelf nut". I thought I'd seen an equivalent saddle. You could make one to give you more saddle thickness for additional saddle compensation.



6. If you don't have enough saddle thickness for full compensation of the low E string, what I'd do is to widen the saddle slot towards the pins - there is enough space to do that. Then fit a thicker saddle to allows the necessary compensation. I'd use a standard nut with that. Only if that doesn't give you "close enough" intonation would I look at compensating the nut. To widen the saddle slot, I'd use a chisel and knife, with which I have a lot of experience.

[Gil80]

Originally Posted by charles Tauber

Looking at the photos, a few observations.

1. you have very little break angle of the strings over the saddle. Try having more than one winding around the tuning machine posts and have the strings wrap progressively towards the bottom. Doing so increases the break angle over the saddle.

2. It is difficult to tell from the photos, but the slots don't look very "clean", as in well-defined. The slots need to be well defined, with well defined breaking points for the strings. If not, you run the risk of intonation issues, buzzing, etc.

3. I don't use the string height above the first fret as a measure. Many people do, but I'm not one of them. Different people have different ways of accomplishing various tasks. The method that I've settled on for nut slots is to use feeler gauges stacked to the desired height adjacent to the face of the nut. You then file until you just touch the top of the feeler gauges with the file. (You can feel when it touches.) It's a method that works for me and takes any trial and error out of the process. Using this method, I'm filing the thing I'm measuring- I'm directly effecting the thing I'm measuring - rather than indirectly filing one thing to achieve a derived result elsewhere (i.e. string height above the first fret). The desired height of the strings at the nut is, theoretically, the same height as the first fret/plane of the frets. Practically, I'll add 3 to 8 thousandths of an inch to that, depending upon the instrument and the specifics of how it is played. Others fret between the 2nd and 3rd frets and look for a minimum gap of the string above the first fret - a "qualitative" approach. Luthier supply houses also sell digital height gauges that allow one to obtain qualitative measurements of the string height above the first fret. Tried that, didn't like it, but it works as well.

4. as you stated, there isn't any further saddle thickness to add more compensation for the low E. Both the A and D strings still have room for additional compensation, probably enough to fully compensate those two strings.

5. One can buy a commercially made "shelf nut". I thought I'd seen an equivalent saddle. You could make one to give you more saddle thickness for additional saddle compensation.



6. If you don't have enough saddle thickness for full compensation of the low E string, what I'd do is to widen the saddle slot towards the pins - there is enough space to do that. Then fit a thicker saddle to allows the necessary compensation. I'd use a standard nut with that. Only if that doesn't give you "close enough" intonation would I look at compensating the nut. To widen the saddle slot, I'd use a chisel and knife, with which I have a lot of experience.

I can't thank you enough for the time invested in your reply and the help you are providing a newbie like me. Much appreciated!!

I'll reply in relation to the points you raised.

1. I didn't fully understand. Any pictures or diagrams? I read it over and over but it didn't sink in :/

2. Got it. I'm trying to work on that. Being broke as I am, I purchased these nut files (still waiting for the item) and in addition, I followed this site to understand more about nut filing.

3. I purchased these feeler gauges (still waiting for them) to follow what you've suggested. In addition, I followed this guide by Frank Ford to understand what is a good way to assess what the string height should be. I didn't achieve it yet.
Seems like I need to cut deeper slots in addition to have them well defined, BUT also make sure the strings are not buried deeply in the slots. Isn't it?

4. Seems like I will run into the issue of having a sharper take off point on the saddle for the A and D if I sand the saddle further back.

5. I was searching in ebay for shelf nut but couldn't find it. Can you recommend on what to buy and how to make my own?

6. That idea crossed my mind. I though of sacrificing my old saddle. I thought of cutting a portion of it and the stick it to the back of the existing saddle to allow a wider base for the low E and then sand it to as required. What concerns me is getting too close to the pin hole and not allowing enough slope for the string. So I'll first try to get the nut corrected and the action set as I want it as stated in my notes at my notebook picture and then I'll try to tackle the intonation issues.

--

Two things come to mind:
1. What is considered an ok/acceptable diviation in intonation? 5 cents? 10 cents?
2. Is it OK to sand down the grooves formed by the strings on the saddle? Mainly looking at the G string.