Bowed soundboard and worn out bridge holes. repair possible?

[landolaguitar]

Hi folks
My old landola has a pretty bad bow . It's the typical kind from string tension pulling at the bridge over the years, and if I'm honest pretty negligible care, I only learned in the last couple years to humidify acoustics during winter months. looked inside and all the bracing seems correct and intact . Is there anything I can do to flatten out the soundboard again? I've haven't strung it in a while but remember it played like butter despite the warping, I'm more concerned about how it effects tone. Also the strings are popping up from their holes. The hole at the low E in particular has gotten pretty eroded/widened. is bridge plate the cure?Any help much appreciated

[B. Howard]

The bridgeplate can be rebuilt rather than replaced. Stew mac makes the tooling to cut out and replace the worn out sections at the holes with pliugs of new wood. I use it all the time and am very happy with the results. Depending on how bad the situation is you may need to pull the bridge and plug the top as well. I can be seen using the tool in this project.
http://howardguitars.blogspot.com/20...ng-braces.html

[Ned Milburn]

The best way to do this is to replace the full bridge plate, IMO. The most difficult part of the job (and time consuming) is to remove the old bridge plate. Heat, plane, palatte knifes, chisel, wooden wedges... I have used all.

Fitting a new bridge plate is not that difficult at all, but fewer people will get a perfect fit than an "ok" fit.

The advantage of full bridge plate replacement cannot be understated. Often, second rate repairs are done where a new bridge plate is fitted on top of the old. This is rarely a good option.

Regarding partial bridge plate rebuilding as Brian suggested, I cannot comment since I have never done it. But it seems to me that a full replacement and repair is always better than a partial repair - especially if the issue is a warped soundboard. Getting the integrity of a new bridge plate that fully spans from one x-brace to the other x-brace, and intersects perfectly with no gap will ensure the best quality repair.

In a few cases, I have added a "L'Arrive" brace. Specifically, this is a spruce brace similar to the other soundboard braces that spans the 2 x-braces parallel with the bridge and just behind the bridge plate. This innovation (that I have been told by a client should actually be attributed to one of Jean L'Arrive Sr.'s first apprentices - David Wren) is structurally very sound, and even decades old L'Arrive guitars show very very little lifting behind the bridge. This additional modification has brought new life to the guitars that received it, and these guitars' soundboards should be trouble free for half a century or more.

[pops]

I have also repaired several bridge plates with the stu mac technique and was very happy with the results. I always use hot hide glue as i think sonically it is better, but in every case the guitar sounded much better. I have replaced many bridge plates too, but try not to be that invasive if i don't have to as i feel this repair does a good job and is not invasive to the guitar. It is also much less expensive to have done.

[Ned Milburn]

Is this the product you guys are referring to:

http://www.stewmac.com/Luthier_Tools...idgeSaver.html

It should also be stated that sometimes warped soundboards and bridgeplates exhibit an accompanying warped bridge that should be removed and replaced or flattened before regluing to ensure the best repair and best possible soundboard re-flattening.

Not a fan of the Bridge Saver at all. Won't allow it near my guitars, and the repairmen doing work for me feel the same way. It removes far more material than necessary. If the holes are worn that badly, they can be plugged and re-drilled as-is, without removing more material.

A much cheaper option is the PlateMate, which I don't use myself, but at least it is nondestructive and completely reversible.

[Ned Milburn]

Originally Posted by Todd Yates

Not a fan of the Bridge Saver at all. Won't allow it near my guitars, and the repairmen doing work for me feel the same way. It removes far more material than necessary. If the holes are worn that badly, they can be plugged and re-drilled as-is, without removing more material.

A much cheaper option is the PlateMate, which I don't use myself, but at least it is nondestructive and completely reversible.

Yes, I have seen the plate mate before and like the concept. It'll add a slight amount of mass with the corresponding slight sonic change, but all in all a nice concise way to deal with the issue of worn bridge plate holes. It won't correct a failed and warped bridge plate and soundboard, however.

---

The stew-mac product I linked to above cannot repair warped bridges or bridge-plates. It can only repair worn bridge plate holes where the ball ends make contact.

[pops]

While the stu mac tool does remove a fair amount of mass it replaces it with approximately the same mass and i feel is stronger than a plug because of the dome area to resist upward forces of the ball. I have used similar PlateMate first before doing the stu mac method and the sound improvement was substantial after taking out the PlateMate and repairing the bridge plate with the stumac tool. This was in the same guitar so easy to gauge the improvement is sound quality. The Plate mate will keep the balls from further damaging the bridge plate, but sonically is no where near the quality of the repair from the stumac tool.

[jaybones]

There is a product called the J L D Bridge doctor. Its basically a block of wood that sits down into the body, attached to the bridge with a screw (or also with brass pins that stick up above the bridge through the holes and allow the string to be top mounted), and a tension rod that can be adjusted at the endpin (which has to be replaced with the one included in the kit). All you need to do is drill the bridge for the screw and drill the end block for the tension rod adjustment. I had one installed in my solid bird's eye maple guitar (bought it new and the soundboard was bellying- I was even humidifying, so figured that I'd better have this installed before things got ugly). Dan Erliewine installed it for me, and cut a plug out of the rosewood bridge and matched the grain so well that even if you know it is there you have to look really hard to find it.

Don't know why more guitar makers don't have this technology. A truss rod to balance the tension of the strings on the neck, why not a similar device on the bridge, rather than leave it up to the soundboard and bracing to handle it?

May be my imagination, but I think the tone and sustain improved after the installation.

[B. Howard]

The worn holes and the bellied top are two different issues. If the holes are worn they need repaired but that will have no effect on the belly in the top.

Here are my thoughts on bellied tops on older acoustic guitars. The top has formed a belly in response to enduring years of string tension pulling and twisting it. The resins in the wood cold flow in response to this pressure and just as floor beams in old houses eventually sag under their own weight the bracing in a guitar sags (or actually bulges) over time. This is a natural distortion of the wood fibers and shows just how elastic wood really is. Martins are some of the worst offenders because of their scalloped bracing which encourages bridge rotation, good for making great tone right out of the box as weaker timbers will always respond more to load but they will also distort more over time.

My feelings on this is that is a natural part of a guitar breaking in and aging. And in cases where there are no failed glue joints in the bracing inside, the bridge plate is tight, there are no major top cracks in the lower bought and the bridge has not rotated beyond a reasonable point I say leave the belly alone. The wood has founds it's own equilibrium under the stress of the strings and has put itself into the most responsive positioning according to it's own needs. Remember that wood last knew it was a tree, it has had to learn to be a guitar. And as stated by the OP these older guitars with bellied tops often play like butter and have nice open tone due IMO to the wood being allowed to find it's way to best do it's job.

My point here is that a failed bridge plate is often not the cause of the belly you see in the top and that the worn pin holes have nothing to do with this situation.

[JIMBO53]

Originally Posted by jaybones

There is a product called the J L D Bridge doctor. Its basically a block of wood that sits down into the body, attached to the bridge with a screw (or also with brass pins that stick up above the bridge through the holes and allow the string to be top mounted), and a tension rod that can be adjusted at the endpin (which has to be replaced with the one included in the kit). All you need to do is drill the bridge for the screw and drill the end block for the tension rod adjustment. I had one installed in my solid bird's eye maple guitar (bought it new and the soundboard was bellying- I was even humidifying, so figured that I'd better have this installed before things got ugly). Dan Erliewine installed it for me, and cut a plug out of the rosewood bridge and matched the grain so well that even if you know it is there you have to look really hard to find it.

Don't know why more guitar makers don't have this technology. A truss rod to balance the tension of the strings on the neck, why not a similar device on the bridge, rather than leave it up to the soundboard and bracing to handle it?

May be my imagination, but I think the tone and sustain improved after the installation.

I'm also a fan of the Bridge Doctor. I used it on some old Yamaha Red Label Nippon Gakki FG-75's and it did a great job pulling the top down, while lowering the action a skoosh, too. Easy to install once you carefully drill the countersunk hole in the bridge. I think the sonic improvement is due to the Bridge Doctor taking the stress off the top, exacerbated by the lifting bridge which is putting longitudinal as well as upward stress on the top. Neutralizing this pull lets the top vibrate normally. I have a Yamaha FG150 RLNG I'll be putting a BD in soon.

[Ned Milburn]

Ack!!! Not this again.

Those who have read my previous posts on the subject will know that I do not consider the JLD Witch Doctor to be a quality solution.

Quite simply:

1) It restricts the motion of the bridge and soundboard, and cannot have an improvement to the tone compared to an unrestricted freely moving bridge/soundboard.

2) The witch doctor does not correct the problem. The warps that it attempts to correct can be caused by failed bridge plates and/or de-laminating braces. If the bridge plate has failed, it should be fixed. If the braces have delaminated, they should be fixed. An extra "L'Arrive" style brace can be added in extreme cases. The bridge itself can be removed, flattened, and re-glued if it is also severely warped.

Use the witch doctor at your own risk. The modification will leave permanent damage on the guitar's bridge, bridge-plate, and soundboard.

A c.1972 Guild dreadnought that I repaired earlier this year would have been a good candidate for the witch doctor, for those repair people who believe it is a good option. Quite simply, it would have killed the guitar's tone and would not have repaired the severe warp/bellying. This guitar was built with a very wide x-brace pattern, and a thin bridge plate. Replacing the bridge plate and adding a "L'Arrive" brace returned this guitar to its full glory - it is loud, deep, resonant, and rich in overtones. I was even surprised at how nice the guitar sounded, since it was one of the louder guitars I have worked on. A witch doctor never could have yielded the same results.

[redir]

I have not used this tool yet but probably will consider it the next time I get a badly bellied top that needs to be flattened. Have you heard of the Thompson Belly Reducer? It's got very good reviews on Stew Mac's site and I think I remember some reputable repair guys here or on some other luthier forum praising it.

It's pretty simple and clever but I imagine it's tricky to get right too but anyway you take two heated metal plates shaped like the bridge and the bridge plate, heat them up and then clamp them in place to melt the glue and reset the plate flat. Then you glue the bridge (which is really a brace) flat down and you are good to go.

Seems much easier then removing a plate which is a major PIA. Also on vintage instruments it saves the original bridge plate which if replaced really hurts the value of the instrument. You know how those collectors are!

[JLS]

Originally Posted by JIMBO53

I'm also a fan of the Bridge Doctor. I used it on some old Yamaha Red Label Nippon Gakki FG-75's and it did a great job pulling the top down, while lowering the action a skoosh, too. Easy to install once you carefully drill the countersunk hole in the bridge. I think the sonic improvement is due to the Bridge Doctor taking the stress off the top, exacerbated by the lifting bridge which is putting longitudinal as well as upward stress on the top. Neutralizing this pull lets the top vibrate normally. I have a Yamaha FG150 RLNG I'll be putting a BD in soon.

I agree.

Old Yamahas respond really well to a properly installed JLD.

Originally Posted by jaybones

...I had one installed in my solid bird's eye maple guitar (bought it new and the soundboard was bellying- I was even humidifying, so figured that I'd better have this installed before things got ugly)...

I don't mean to pick on you, but that is backward thinking. You say, "...I was even humidifying..." as if that should have prevented bellying. Humidifying increases the belly. In fact, too flat a top is a potential indicator that the guitar is dry. It's why dry guitars sometimes start to buzz. The top has flattened and lowered the strings too close to the fretboard.

Originally Posted by jaybones

...Don't know why more guitar makers don't have this technology...

Because it's counter to what nearly every builder believes about how flattop guitars should work. The BD would have to be licensed, but the technology would be easy enough to work into a nonproprietary design if there were any merit to it.

Originally Posted by jaybones

...May be my imagination, but I think the tone and sustain improved after the installation.

Good tone is subjective, but adding mass to the bridge will improve sustain. For most musical uses, any decent acoustic has more than enough sustain to do the job without the extra mass.



Ned, Bruce Sexauer refers to the BD as the "Tone Doctor". I'm thinking of adopting your nomenclature though.

And we also agree that it can do nothing good for tone. Flattop guitars are designed to work against the string tension. A top that is restricted by that extra brace and weight will not function as designed, or very well IMO. Most of the repairmen I work with have a bucket full of ones they've removed.