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Guitar Repair Help Please

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martincl

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Background: The guitar is about 40 years old. Brand: Almeria (made in Spain). Style: Classical/flamenco. Current cost new: about £150 (so budget level).

My wife has just picked up her old guitar from her parents’ house with the view of trying to play again. However, in the interim, one of her younger brothers had restrung the guitar with steel strings which have deformed the bridge and guitar body (front face) significantly. As far as I can tell the neck and fretboard are still pretty true.

The Damage: The bridge had been twisted/distorted and the back had lifted off the front face of the guitar body (see below), but not before it had “bellied out” the back of the area on which it was seated/glued. After several hours with an iron, spatula, and surgical scalpel, I have managed to remove the bridge, but not without pulling away some of the wood under it. (I now realise that using a chisel and then heat to remove the last of the glue would have been the best way to go – but too late now!)
distortion-2.jpg

What I need to do!

1. I have to fill and level the area where the bridge was. The back of where the bridge was seated is 1mm to 1 1/2mm higher than the front due to distortion, so I need to level this area up and create a flat surface for the new bridge. Is wood putty suitable and does it have enough adhesion to stay attached, or should I be trying something else? Any other ideas or suggestions?
20210622_163824.jpg

2. I need to fit a new bridge once I have completed the step above. The old one had 2 small dowels in addition to the adhesive. “If” I am successful in the task above, what type of adhesive should I use? Should I try to use dowels too, or even screws? Any suggestions, ideas, do’s and don’ts would be very welcome.
distortion-3.jpg

Ultimately, this is not an expensive guitar, but it would be nice to make it playable again. I am pretty able as a DIY person, but this is more intricate than the kind of thing that I would normally take on. Any help/advice would be greatly appreciated. Thanks.
 

profchris

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That bridge has come off pretty cleanly, so don't do what you planned!

The steps to repairing this are as follows:

1. Check that the bracing for the top (around the bridge area) hasn't come unglued. Reach inside and wobble the braces by hand - if they don't move you're probably fine. Also try sliding a thin feeler gauge under them. Check particularly under the distorted bridge "wing". If any braces are loose, you need to work glue into the separation (feeler gauge would work for this) and work out a way to clamp them while the glue dries. Titebond original is recommended for this, and all the other glueing.

2. Don't throw the bridge away! Scrape off any glue residue you can see underneath with a chisel, but leave any slivers of soundboard material. Use a medium clothes iron (wool setting) to iron flat the distorted wing, or at least fairly flat.

3. Scrape glue residue off the top within the bridge footprint. Remove that stub of dowel with a chisel.

4. Offer up the bridge to the top and see whether it sits flat enough so you can push any remaining distortion out with finger pressure. With luck any slivers of soundboard material will lock it into place. If so, ignore the dowels - they just locate it, they don't make the connection stronger.

5. Work out how to clamp the bridge to the top - you can buy special clamps for this, probably costing close to what a replacement guitar would be, so you'll have to improvise. But if you can work out a clamping system which flattens out the distortion and holds the bridge down at three places (each wing and the middle), then apply glue, clamp at least overnight, remove glue residue (a happy half hour with a warm, damp cotton bud), string up and play!

If the bridge will press flat but you can feel there isn't a good wood to wood fit across the whole width, then use epoxy instead of Titebond Original. This makes it a one-shot glue up, so practice several dry runs.
 

martincl

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Thanks profchris

The bridge is, I am afraid, gone. I could not get heat to pass through it very well, so I used a multi-tool to cut away the section that holds the saddle in order to get better heat transfer to try and melt the glue. A lack of forethought on my part.

What I cannot convey with pictures is the extent to which the front face of the guitar (where the bridge sat), is ballooned up. If I place a straight edge on it, it is significantly raised both widthways and lengthways. A new bridge (or straightened old one) would only make contact with the central 40mm-50mm of the guitar face and only at the very back (of the 30mm width of the bridge), maybe 5mm to10mm. I have attached another photo to try and show this with a straight edge. You can get a teaspoon handle under the gap. I think that the steel strings have been on for over 20 years!
ballooning.jpg

I have had a really good feel around in the body of the guitar and I cannot find anything loose or any gaps (my wife has done the same). I cannot get a scalpel under any joint or connection. There is no flexing of the front face of the body and the deformed area does not want to be flattened out.
 

Tuna808

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You can buy ready made bridges which are not expensive ,the problem is the saddle position as if its not where the previous one was it will affect the intonation.
Having checked that the bracing and struts are not compromised as as suggested,i would proceed by solving the method of clamping as this will be crucial in the gluing stage…
i would cut a 18mm or 25 mms piece of ply bigger than the bridge and dry clamp it for a few days and check if the top will flex enough to flatten against its mating surface…..tops are usually tapered from bass to treble on handmade guitars,usually the thickness will be no more than 3 mms on the thickness section .
i would moisten the area around the bridge and clamp the plywood making sure that the top gives way to the plywood mating face.
You might have to reinforce the top directly below the bridge position with some spruce if you have any otherwise 3mm pine will do as alternative,you will have to take the fan bracing into account if you do this…..i would go much bigger than say 20 mms bigger than the bridge…….clamping will again be an issue if you proceed with the under bridge reinforcement.As prochris has said specialist clamps will probably cost you more than what than the guitar is worths but you can make your own clamp or clamps with a bit of creativity.There are wooden clamps which use a cam locking device which can be easily made and not costly at all….it all depends on the time and effort you want to put in this repair.
Main issues will be …..clamping……saddle position…..possible under bridge reinforcement.
as for the glue,epoxy glues will have better gap filling properties than the PVAs if gap filling is an issue.
 

Tuna808

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Just seen under articles there is an article on how to make luthiers clamps by Charly…..check it out
 

thetyreman

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oh dear that's not good at all, the bridge area needs to be flat for the saddle to be re-attached, so you'd have to put a new top on it and sort out the unevenness, this is a job for a professional luthier who specialises in making classical guitars. I would get it repaired but only if you really value it and it has a special sentimental value to it, because the repair will cost more than what the guitar is worth.
 

Ttrees

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Since you say its a cheap guitar, and if you want to learn skills
I suggest filling the hole with a patch, and match the grain even though its likely a laminated (plywood) top (soundboard)

I have had a bridge on a classical fly off before and used epoxy to fill a gap, which didn't hold.

I wouldn't be too concerned about the top being bellied, you can match the profile by hollowing out the middle of the bridge blank
until the edges have contact, test with a clamp to see how it fits, regular wood glue is all I've ever used after that.
Make sure the edges aren't sitting on any lacquer though.

If you want a playable guitar, then you likely will need to do a neck reset.
I'd convert it to a bolt on, as its likely dowels holding it together.
Frank Ford on frets.com has an helpful article on making a backwards drill bit, for a guitar like this.

I have sawn off necks before, using a very thin saw I wouldn't advise it.
I've taken necks off with a hair dryer after loosening the the fret board extension with a hair drier and damp cloth beforehand.
I'd try that again, rather than think about sawing the heel again and ruining a saw blade, or two.

John Hall of blues creek guitars on youtube has some tips on neck setting
Definitely worth a watch, even if you decided to forget about this and just buy a cheapie guitar, as you would be better informed you weren't buying a lemon.
Under a price point, you'd be hard pressed to find a guitar in spec regarding typical figures for action (height of strings above FB)

If it all goes south you could make a proper guitar soundboard from
tight grain spruce, "a solid top" it doesn't need be a singular bookmatched top.
Jose Romanillos reckons that doesn't make much difference in the scheme of things.

Tom
 

Tuna808

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Guitar tops are quarter sawn so they can be gently persuaded to retake their shape especially on a localized spot.A top replacement would not be cost effective and labour intensive quite frankly you might as well build a new one.
First stage is to sort out the clamps,without adequate clamps the repair will be a non starter.
 

Ttrees

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Ha ha, that's an old one, and is still the best.

So how much does a real guitar with a solid top cost anyway?
What!!!! Well, I got nothing to lose by having a bash. :cool:

More power to your elbow, and don't be too hypnotized by those stu mac catalogs, yes some things are good, but you don't need everything... you've been warned!

Ps the OLF official luthiers forum is the place to search, although you will likely get scorned for even mentioning a laminated top.

Tom
 

Tuna808

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You can buy ready made bridges which are not expensive ,the problem is the saddle position as if its not where the previous one was it will affect the intonation.
Having checked that the bracing and struts are not compromised as as suggested,i would proceed by solving the method of clamping as this will be crucial in the gluing stage…
i would cut a 18mm or 25 mms piece of ply bigger than the bridge and dry clamp it for a few days and check if the top will flex enough to flatten against its mating surface…..tops are usually tapered from bass to treble on handmade guitars,usually the thickness will be no more than 3 mms on the thickness section .
i would moisten the area around the bridge and clamp the plywood making sure that the top gives way to the plywood mating face.
You might have to reinforce the top directly below the bridge position with some spruce if you have any otherwise 3mm pine will do as alternative,you will have to take the fan bracing into account if you do this…..i would go much bigger than say 20 mms bigger than the bridge…….clamping will again be an issue if you proceed with the under bridge reinforcement.As prochris has said specialist clamps will probably cost you more than what than the guitar is worths but you can make your own clamp or clamps with a bit of creativity.There are wooden clamps which use a cam locking device which can be easily made and not costly at all….it all depends on the time and effort you want to put in this repair.
Main issues will be …..clamping……saddle position…..possible under bridge reinforcement.
as for the glue,epoxy glues will have better gap filling properties than the PVAs if gap filling is an issue.
BTW plywood is just to persuade the top to it original shape or near enough,dry clamped for a few days and then discarded 😃
 

martincl

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THANKYOU all for your tips, recommendations and advice. What a fantastic forum. I will proceed with the repair and, as seems to be the first task, try to find a clamping solution to sort out the bowing, then the gluing. As I said, the guitar is not an expensive one, so passing it to a luthier would not be cost effective, but it is definitely worth me having a shot at it.

I will post the outcome. Thanks again for all your help.
 

thetyreman

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the saddle needs to be in exactly the right place, I'll be intrigued to see how you fix this.
 

Tuna808

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In theory the distance from twelfth fret to the saddle should be the same a from the nut to the twelfth fret,in practice it is not uncommon to find the saddle to twelfth fret just slightly longer to allow to an increase in string length when the sting is pressed down.I would in this case play safe and locate it on the distance given from the nut to the twelfth fret……….might be case of making a simple jig to find the exact position for the new bridge.
 

martincl

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I do have a measurement for the position of the saddle, but I was hoping to get a bridge that was the same dimensions as the original with the same location of the saddle and use the original bridge positioning. I did not realise that it had to be absolutely perfect.
 

thick_mike

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Frets.com is a great resource for this sort of thing:


it’s over several pages, so you’ll need to click “more” at the bottom of the page.
 

thick_mike

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Cannot recommend this huge resource enough. It’s full of knowledge, tips and tricks for instrument repair generously shared by a highly skilled luthier who specialises in repair.

 

novocaine

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I don't think the sound board has pulled up, I think it might have collapsed around the sound hole. without knowing the bracing arrangement I'd guess at a fan braced or ladder braced sound board with little to no bracing once around the sound hole. a thin top would possibly want to deform towards to the sound hole with high tension across the saddle and neck. normally this would result in a distortion at the neck joint but I can envisage this being telegraphed back to the weakest point and bellying inwards.
Can you place straight edge across the entire sound board, not just the saddle area to see where the deformation is, it should be convex from around the mid point to the outside in both planes, . how convex is a different matter but it should can be anything from a 5-10mm.

it is still fixable but may need some less than normal methods, possibly including holding on to the sound hole and bouncing the guitar to try and "pop" the concave area back over to convex or, and this one amuses me, a small jack through the sound hole. :)

this popped up on a feed a while ago, look familar?

https://www.reddit.com/r/Luthier/comments/btntz2
 

Roland

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By coincidence I’ve just done one of these, although I was able to re-use the original bridge plate. The advice I was given was, first, make sure the bridge plate and body make contact over all their area. Secondly work out a clamping scheme. You don‘t have to use specialist clamps if you can use cauls to transfer the pressure. Lastly, bolt down the new bridge plate with large washers inside the body, because a re-glue is never as strong as the original build.
 

martincl

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Thanks again everyone for all the help, advice and site recommendations (frets.com etc).

The guitar is entry level and appears to be ladder braced. When I run a straight edge along it at various positions it would appear that, whilst the area to the back of the bridge has definitely deformed out (in a very localised area and is visible to the naked eye), it has, as you suggested novocaine, created a second convex distortion between the sound hole and the bridge position. (Sorry about the overly long sentence!) It looks as if trying to restore the correct profile is going to take a multi-pronged approach, but I cannot walk away from this now. I am looking at the various resources and suggestions that you have all generously given to me and I intend to start on this at the weekend. I suspect it will be a longish task to sort the problem out, but I am sure that it can be done.
 

profchris

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All guitars do this - they try to eat themselves through their own sound hole - unless they are so overbuilt that they are nearly silent!

Usually they stop after a few years, and then never (or rarely) get worse, unless they aren't strong enough to stand up to string tension. If you put nylon strings on this, there's a good chance it won't move any further.

There is little point trying to correct the dip in the top. Wood is a plastic substance, and takes on a set over time. A fix would involve removing the top, removing the bracing, building a mould of the desired shape, and then removing (or reducing) the deformation using heat and weighted bags (sand or lead shot) and re-bracing. So we can rule that out here, I suggest!

The normal fix is to re-set the neck so the plane of the strings is correct - with the action (height between bottom of string and top of fret) at the 12th fret around 3mm, the string should arrive around 3mm above the top of the bridge. This gives you 3mm of saddle projection, and you can take it down a little once strings are on as the top will probably rise around 0.5mm.

On a guitar like this, the easiest solution I can think of commensurate with its value is:

1. Drill a hole from around 2/3 down the heel from the fretboard through into the body of the guitar to take a bolt - 5mm or 6mm. Countersink the heel enough to get the bolt head below the surface of the heel.

2. Using a flush cut saw with a thin blade, cut from the bottom of the heel up to the bottom of the fretboard, protecting the sides with thin shim stock metal (or tape if you are prepared to keep replacing it). Nylon string guitars don't normally have truss rods, so there should be no metal in there. If in doubt, check with a strong magnet.

3. Get a scrap of something the same height as a fret and tape it on the fretboard next to the nut. Get a 3.5mm drill bit (or wrap a 3mm drill bit in tape until it is around 3.5 mm) - this will sit around 3mm above the frets. Tape that on the neck next to the 12th fret.

4. Work out where your saddle needs to go. Scale length = distance from nut to 12th fret x 2. On a nylon string guitar the saddle needs to be scale length + around 2.5mm on the low E, 1.5mm on the high E. If you are using a wide saddle, say 3mm, place its front edge at scale length + 1 mm and then you can file back at each string location to make the 12th note fretted exactly an octave above that string's note played open.

5. Fit your bridge to the top at that place (or you could fit it where the old bridge was, fill the saddle slot and cut a new slot at the right place). It needs to fit the curvature of the top via sanding (sandpaper taped to the top). Glue it on.

6. Take a straight edge, place one end on the spacer you taped at the nut and rest it on your drill bit - you want it to be 3mm above the bridge at the saddle location. It won't be, so ...

7. Use sandpaper with parcel tape on the back to floss between the heel and the body (push up neck, slide paper in, push down gently, pull paper out without rounding over the sides of the heel - repeat lots of times, remeasuring as you go).

8. Once the neck is correct, insert bolt, tighten nut inside, string up, shape saddle and play! If you want to touch up any chips and blemishes around the neck join, do this before you bolt it on.

9. Once you're sure that everything lines up nicely, you can fill the hole around the bolt head and do cosmetic work. Or leave it, as evidence of how clever you've been.

There are other ways of doing a neck reset, but they all depend on you knowing how the neck is attached and having skills (via practice) that the OP probably doesn't have.
 
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