Tips for repairing flat soundboard

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Joan Maher

Posts: 213
Joined: Dec. 3 2013

Tips for repairing flat soundboard

Hi Guys,

any tips out there existing or new to repair a slightly sunken flamenco top - keen to remove the top as i think by placing a slightly curved brace I can restore the right level of doming on the top.

I have just removed the bridge and the trick part is how do I glue the bugger in!

Thanks in advance for any useful suggestions.

Joan.

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Gracias!

Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date May 25 2015 14:09:55

estebanana

Posts: 9352
Joined: Oct. 16 2009

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Can you show a couple photographs of the problem against a flat ruler which shows how much distortion there is in the top?

Where is the distortion and how much is it distorted?

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REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 6:46:57

Joan Maher

Posts: 213
Joined: Dec. 3 2013

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Yes will do - just travelling with my day job and will post at weekend.

it's slightly sunken just above the bridge area.

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Gracias!

Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 8:00:04

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Slightly sunken in front of the bridge is fairly normal I would say. I would also assume that it was raised behind the bridge too.

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REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 10:26:11

Joan Maher

Posts: 213
Joined: Dec. 3 2013

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

yes it's a little raised at the centre - the bracing is similair to this one attached here in the picture. so just wondering where to add in new brace supports.

Images are resized automatically to a maximum width of 800px

Attachment (1)

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Gracias!

Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 11:45:46

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

I mean normal as in there is no need to repair anything.

Lets wait until we see the picture first. Some cases are pretty bad and effect the action and playability of the guitar.

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REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 12:19:57

estebanana

Posts: 9352
Joined: Oct. 16 2009

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

If it is sunken in front to the bridge and is not 'S"curved so much that it is effecting the working action of the guitar, then like Eden says, not a problem.

If there is a slight depression in front of the bridge, and the between the tail block and bridge there is some lift, AND the action is good, then the guitar is functioning. If the top is dished in front of the bridge and this seems to be effecting the string height in a radical way preventing the instrument from playing then it's a problem.

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REPORT THIS POST AS INAPPROPRIATE | Date May 26 2015 12:59:08

Joan Maher

Posts: 213
Joined: Dec. 3 2013

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

quote:

If the top is dished in front of the bridge and this seems to be effecting the string height in a radical way preventing the instrument from playing then it's a problem.

Yep it's this one - see attached pic. I checked the action (very high) etc which is why I removed the bridge as it was leaning forwards slightly.

I will have a think this week how I approach it any suggestions welcome.

Images are resized automatically to a maximum width of 800px

Attachment (1)

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Gracias!

Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 10:33:27

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

I see I thought you meant dished the other way!

That looks like what happens when you glue your harmonic bars on in high humidity.

I can't think of an easy fix for that one. I have retopped for less

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 13:26:57

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Could you do the same picture over the lower harmonic bar?

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 13:52:24

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Its a very radical bracing system leaving almost no support where all the tension is so it has more or less colapsed or imploded. To be honest, my only thought is: Why bracing like that?
You can maybe save it, but most probably you´ll have to take off the top or the bottom of the guitar and I dont know if its worth it. Wood can be very stubborn and when it has taken a decission to go one way it might be impossible to make it go another way. It might be easyer, and I believe better to make a new top for it. (with another bracing)

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 21:24:00

Andy Culpepper

Posts: 3023
Joined: Mar. 30 2009
From: NY, USA

RE: Tips for repairing flat soundboard (in reply to Anders Eliasson)

quote:

Why bracing like that?

Right... put all the stiffness at the edge where it is already and very little in the center where it needs it. Well it looks "radical" enough that it might help sell some guitars

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 21:33:21

flaco

Posts: 17
Joined: Jan. 13 2015
From: Cosmos

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Well, if you don't want change the soundboard, i'll go for a modified bridge that compensate the concave dishing.

If you're up for some kind of experiment you can remove the top, assuming you get it without hurting the guitar you can sand it (the top), then humidify it and try to dish it the other way... maybe removing the braces would be necessary.

But again, only if you're in for an experiment.

Changing the soundboard will be better for you guitar than humidifying it...

Good luck !

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 22:34:46

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Looks like whoever made your guitar has been looking at some bracing patterns by Paulino Bernable. I suspect trying to fix this problem is hopeless paticularly considering the state of your fingerboard and frets. If you really want to proceed with trying to fix it put a big, stiff brace with a light arch in it running side to side about half way between the bridge and the lower tone bar. You will have to relieve it for the center fan brace. All you need is about 5 cam clamps and some Titebond glue. The guitar will probably sound terrible but there's a slim chance it might help with your problem.

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REPORT THIS POST AS INAPPROPRIATE | Date May 27 2015 23:02:59

estebanana

Posts: 9352
Joined: Oct. 16 2009

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

If this were a guitar by an important maker I would say a careful restoration would be in order.

It would be good to see the straight edge placed on the center seam of the top and then a photo from the side to see the overall distortion from fingerboard to end block at the tail. That whole line tells more of the story and how the straight edge shows the condition of the top as it moves over the lower lateral brace and the bridge area.

But since it's not a known maker worth saving, you have a golden opportunity to make a better guitar by making a new top with a sensible bracing pattern. I would consider that very seriously rather than a fix based on trying to fortify an odd original bracing pattern.

If you make a new top you gain in several ways and end up with more or less a new guitar.

You could also peel the original top off the ribs by razor sawing it away from the blocks or even routing around the rim. And leave the two lateral braces intact by carefully releasing the glue or just carefully planing the old top material off the braces.

Then make your new top with just the fan bracing and rosette patches in place, then glue the new top to the existing lateral braces with C -clamps. Then you save more of the original guitar and you don't have to try to refit new lateral braces to the ribs with pillars under them. It is nice to leave the original lateral braces because it leaves more of the original structure intact, provided those two braces are in good condition and properly arched under the sound hole.

In any case when I re-top a guitar I leave the lateral braces intact as I remove the old top. The reason is that these two braces hold the structure of the guitar in place in case you can't put the new top on right away or if you seen to study the situation further before making the new top.

So I'm saying don't just rip the existing top off and leave the rib structure without some fortification to keep it from distorting more. Without the top and the lateral braces the ribs can change shape slightly. So before you do anything like taking a top off, make a tracing of the outline of the face of the guitar on a big sheet of paper. Then you have a record of the exact shape of the ribs. And consider carefully whether or not to remove the lateral braces.

Just a few thoughts on re-topping, everyone does different things, mileage may vary.

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REPORT THIS POST AS INAPPROPRIATE | Date May 28 2015 1:14:34

Joan Maher

Posts: 213
Joined: Dec. 3 2013

RE: Tips for repairing flat soundboard (in reply to Joan Maher)

Thanks guys,

some very comprehesive feedback - I think the bracing is the main cause and I was told it was left in a very hot flat over last summer.

I will consider all the options given and let you know how I get on!

Many thanks all

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Gracias!

Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date May 28 2015 10:29:43