Repair of guitar - what needs done?

Construction and repair of Classical Guitar and related instruments
Peskyendeavour
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Repair of guitar - what needs done?

Post by Peskyendeavour » Sun Jul 23, 2017 12:34 am

:aide: :aide: :aide:

I have a friend whom I visit often - they have a guitar that could not be tuned somehow.

So if you tuned the open strings so that they are in tune as soon as you press, the other notes are not in tune with the open strings. And then, as you press up the frets, each note is sharp (from the note it's supposed to be) by a different amount.

So one fret maybe 17.5C up next could be 3.5C up. (See pic on the +13C I'm not sure what it's measuring but I know I can hear it being off if more than 10) All the strings suffer from the same issue, but same frets on different string don't go up same amount, the higher strings (1)(2)(3) are worse.

Is the bridge out of place or the frets all out of sync? Can it be fixed? How? Would it be an expensive fix?

[ok having problems loading pics - not sure what's wrong with attachment. But maybe you don't need pics of guitar to help me?]

MessyTendon
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Re: Repair of guitar - what needs done?

Post by MessyTendon » Sun Jul 23, 2017 6:28 am

The nut and saddle is always a good place to start...Are the frets worn out? Fret dressing/saddle, nut can help a lot.

Another silly culrpit could be as simple as how the strings are tied...a bad tie job...you can have the strings slip like crazy. Try tying on a fresh set of strings...D Addario are reliable in the intonation department. Good luck.

Peskyendeavour
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Re: Repair of guitar - what needs done?

Post by Peskyendeavour » Sun Jul 23, 2017 4:36 pm

I'm trying again with photos as that might help.

The instrument is not slipping in tune as you play. It's actually not able to be in tune with itself despite trying damn hard to tune it.

I can't see anything the matter with the nut or bridge /saddle per se apart from the part that touches the string seems quite wide, and the shape is different from my guitar, but not knowing many guitars I don't know what is right.
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Peskyendeavour
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Re: Repair of guitar - what needs done?

Post by Peskyendeavour » Sun Jul 23, 2017 4:42 pm

Also the frets are not worn. The guitar is almost mint new guitar although quite old now but hardly played much due to its being out of tune and not therefore favoured by the owner who is really a violinist and can hear the out of tune- ness quite easily and can't bear it.

I visit quite often so would like to be able to play it (and not to have to bring mine) - so for selfish reasons want it fixed!

:o :aide: :merci:

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Manuel Najera
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Re: Repair of guitar - what needs done?

Post by Manuel Najera » Sun Jul 23, 2017 6:20 pm

My guess would be a bridge glued on the wrong location.
Try measuring the distance form the nut and the 12th fret, and the distance between the nut and the saddle. You should see that one is exactly twice the other one. If not, then my theory is correct.

OldPotter
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Re: Repair of guitar - what needs done?

Post by OldPotter » Sun Jul 23, 2017 6:39 pm

I don't know the answer to your question, but can start with a few basic things. It looks as though the fret board nut and saddle have been assembled incorrectly, hard to know which part is wrong. If, for example, the first fret is in the wrong position by 17.5 cents, then it would need a correction of around 6mm. It sometimes is possible to cut away part of the nut to alter the intonation. But the nut looks to be about 6.25 mm thick, so not enough space to make a correction.
I looked at the fret position calculator on the stewmac website, to see what a standard scale fret position is. You could do the same and check your guitar with a ruler. Ideally it would be better to use a more accurate measuring system. I did see a number, 630, on the guitar label. I'm not sure if that is a model number or a scale length. A standard guitar is a 650mm scale. It would be worth while to check your scale length, see the notes at the stew mac website, and do a rough check of the fret positions. If they are seriously out then it would mean a new fret board. Probably not worth it. It would depend on the costs of your local luthier.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain

Peskyendeavour
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Re: Repair of guitar - what needs done?

Post by Peskyendeavour » Sun Jul 23, 2017 7:06 pm

Ok - I just left that guitar to head home but will get those measurements done to check.

If the saddle needs correcting is that expensive ?
The guitar is only £250 itself... would it be worth the repair ?

Peskyendeavour
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Re: Repair of guitar - what needs done?

Post by Peskyendeavour » Sun Jul 23, 2017 7:22 pm

PS - scale length, at the saddle - do you measure the centre point? Since it is at a slant... how much of a slant for compensation is normal?

OldPotter
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Re: Repair of guitar - what needs done?

Post by OldPotter » Sun Jul 23, 2017 7:23 pm

The actual length of the strings is usually more than the scale length, typically 652 for a 650 scale. The error you mention is quite large. If the error is in the saddle, then there is about 3mm room for a small correction. That would mean having the peak height of the saddle adjusted forward or backward. Probably a new saddle needed, not expensive. If you can do some measuring to have a look at the scale length and fret positions, then its easier to think about what to do next.
The true scale length is measured by doubling the distance from the front edge of the nut to the crown of the 12th fret. See the notes at the stew mac website.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain

astro64
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Re: Repair of guitar - what needs done?

Post by astro64 » Sun Jul 23, 2017 9:36 pm

Manuel Najera wrote:
Sun Jul 23, 2017 6:20 pm
My guess would be a bridge glued on the wrong location.
Try measuring the distance form the nut and the 12th fret, and the distance between the nut and the saddle. You should see that one is exactly twice the other one. If not, then my theory is correct.
I don't think that is correct. Most guitars would need some compensation, so twice the distance from nut to 12th fret should be somewhat smaller than the distance from nut to saddle.

John higgon
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Re: Repair of guitar - what needs done?

Post by John higgon » Mon Jul 24, 2017 7:13 pm

astro64 wrote:
Sun Jul 23, 2017 9:36 pm
Manuel Najera wrote:
Sun Jul 23, 2017 6:20 pm
My guess would be a bridge glued on the wrong location.
Try measuring the distance form the nut and the 12th fret, and the distance between the nut and the saddle. You should see that one is exactly twice the other one. If not, then my theory is correct.
I don't think that is correct. Most guitars would need some compensation, so twice the distance from nut to 12th fret should be somewhat smaller than the distance from nut to saddle.
I think the distance from the nut to the 12th fret should be 315mm, and the distance from the 12th fret to the saddle should be close to 317, bringing the total scale length to 632 or thereabouts, for this particular guitar. If the bridge is in the wrong position it should be fairly easy to plane the old one off and put on a new one, but if the frets are out of place I'd wonder whether the cost of repair would exceed the cost of a new guitar.

johnparchem
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Re: Repair of guitar - what needs done?

Post by johnparchem » Tue Jul 25, 2017 2:20 pm

Is the nut flipped around? I looked at the picture and could not tell but it is an easy post build way to get this result on a properly built guitar.

MessyTendon
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Re: Repair of guitar - what needs done?

Post by MessyTendon » Tue Jul 25, 2017 3:28 pm

Tie on a new set of strings...look at your loops on the trebles...that's not quite right. Don't do major surgery till you try the little stuff.

SteveL123
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Re: Repair of guitar - what needs done?

Post by SteveL123 » Tue Jul 25, 2017 4:02 pm

MessyTendon wrote:
Tue Jul 25, 2017 3:28 pm
Tie on a new set of strings...look at your loops on the trebles...that's not quite right. Don't do major surgery till you try the little stuff.
+1
He's tie-ing the strings wrong.

https://www.youtube.com/watch?v=mGO30uYiIaY

Peskyendeavour
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Re: Repair of guitar - what needs done?

Post by Peskyendeavour » Tue Jul 25, 2017 11:59 pm

John higgon wrote:
Mon Jul 24, 2017 7:13 pm
astro64 wrote:
Sun Jul 23, 2017 9:36 pm
Manuel Najera wrote:
Sun Jul 23, 2017 6:20 pm
My guess would be a bridge glued on the wrong location.
Try measuring the distance form the nut and the 12th fret, and the distance between the nut and the saddle. You should see that one is exactly twice the other one. If not, then my theory is correct.
I don't think that is correct. Most guitars would need some compensation, so twice the distance from nut to 12th fret should be somewhat smaller than the distance from nut to saddle.
I think the distance from the nut to the 12th fret should be 315mm, and the distance from the 12th fret to the saddle should be close to 317, bringing the total scale length to 632 or thereabouts, for this particular guitar. If the bridge is in the wrong position it should be fairly easy to plane the old one off and put on a new one, but if the frets are out of place I'd wonder whether the cost of repair would exceed the cost of a new guitar.
Ok so which bit of the saddle do I measure to to get the scale length?
I'm still a bit puzzled how this is measured and whether it's the centre point or at 1st/6th string which would differ more than 2mm and you have given quite accurate to the mm measurements ...

Checking what I should be checking for her

Though noted that she might like to restring too...

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