1957 J 45 With " Bubbled Top " issues

[thefishinmusician]

 The patient,..A 57' J 45..It's been ridden hard and put away wet....The bridge has been replaced with a solid saddle hand made affair that is way too thick....That is now off the guitar, and can easily be decreased in size, and give me good saddle hight( there was none )..and good action..The big problem....The top dips down in front of the bridge, and there is a pronounced " Bubble " behind it...There was only one loose brace...( see drawing )..and that does not look like a major contributer to the problem...On a cheap plywood guitar, which I see tons of, I would just make a larger bridge plate to pull the bubble out...I'm thinking of a modified extended plate to pull it down,..( again, see drawing )...And I would like to hear some opinions on this design...Would it be less tone killing than just a larger plate?...How would you approach this problem?...The customer doesn't have a big pile of money to spend on this, and plans on keeping the guitar till forever..Neck,frets, finish, all pretty good...Also, since the bridge has been off twice, It's a bit ugly underneath..( It had the adjustable saddle )..Lot's of wood is missing, and holes were not plugged or filled....I have some close to quarter sawn maple for the new plate, altho' to make it as wide as the original, and keep the grain running opposite of the top grain, I'm tempted to join small ears on the sides of the plate to make the width right....Love to hear some opinions!...Thanks!

[Ned Knepp]

Amateur Ned here but it seems to me that that loose X brace could contribute to the problem. Without it, the bridge probably wouldn't have rolled as much. I think I would try to get the face flattened before I replaced the bridge. I also don't think I would over size the bridge plate much, if any, but I would consider adding a Bridge Doctor to hold things in place when I replaced the bridge.

The first really good guitar my brother had when we were teens was a mid '50's J 45. Even with light strings it was a great, booming bluegrass guitar. It had bass to spare and wasn't too bad on trebles either. It was not the most balanced guitar I ever played but it was still a great guitar.

[Stuart Horsman]

We've had good luck with adding a small maple brace crosswise between the "x-braces." One, at the leading edge of the bridge plate,and a second between the cross and the soundhole.We first tried this repair as a last resort to save a self-destructing 12-string. While it may not correct all the buckling, it will often remove a surprising amount, and offers support against further rotation. A job for "the smallest hands in the shop." Stuart Horsman

[David Houchens]

Send it to the old guitar home,...... Mine. These can be great guitars.
As Ned has pointed out, light strings are generally fine on these guitars. Most D28s too if people would pick them a little easier and let the guitar sing instead of over riding the strings.
I had a D35 with really severe raising behind the bridge come in the shop. The raised part was only between the lower X legs. It had been this way for a long time. One whole leg of the X was loose and part of the other.
I could raise the bracing with my fingers easily. I had no reason to belive they would hold anything by just regluing. The owner didn't really like the idea of a Bridge Dr hanging inside (I have fixed several guitars with these. They can work).
The guitar's overall condition was never gonna command any vintage money, so my choice was to remove the back, remove the bracing and flatten the top with light moisture and a bag of lead shot. Always put wax paper or the like under the shot bag, They can bleed out a grayish black mess.
I rebraced using taller but still 1/4 wide bracing. Sanding a 25 ft radius in the bracing, which gave the whole top a slight arch, narrow maple bridge plate and set the neck to the new top shape.
This was only a year and a half ago, but the top is holding fine and the guitar sounds great according to the owner. It was a lot of work but the out come was worth it.

[thefishinmusician]

In a perfect world with unlimited funds, I would love to take the back off and do that....But that would cost him far more than he wants to spend...That's why I'm looking at bringing it down with" braces " on the bridge plate...I am going to make an aluminum caul to heat and clamp to the underside of the bubble. to flatten it out some before replacing the plate..

[Bob Steinarsson]

Take a look: http://fretsnet.ning.com/forum/topics/warped-flat-top-tops
The "towel bag" method worked well, but I don't know how long time the top would keep flat without the Doctor.

[thefishinmusician]

The actual bridge area is pretty flat...It's bubbled behind, and dipped in front....I got one of those bridge doctors once, and for the life of me could not understand it...Left brain, right brain....I'm useless in electronics the same way...I just don't think it's a good enough option on this baby....

[Bob Steinarsson]

I still think it may be a possible solution for you. My experience tells me this:
1. The Doctor presses the area behind the bridge down and pulls the area in front of the bridge up. It does not flatten the bridge area specifically.
2. The "towel method" pressed the area behind the bridge flat (this belly was very hard. The Doctor alone would not have been able to press the area flat). This was possible because the whole area, top, plate and bracings, became more humid (not wet) than normally.
3. I think that any flattened belly/bubble will fatten again without resistance (my presonal belly is like that too). That is where the Doctor can do its job. It will keep the top flat, because it prevents the belly/bubble to rise.
4. If it is possible to force the belly/bubble down by hand, the Doctor will do the job alone, both flatten and keep flat.
5. This is a small job with great effect.

My guitar has a laminated top. I can of course not guarantee that everything works like this with all guitars, but I think that the risk is small as long the interior of the guitar does not get soaked. Glueing a brace is no big thing, especially as long as it is soft after the "Towel method". I think that after the glueing and drying, the bracing has "forgotten" the bend that made it come loose. Take care that no water leaks out from the plastic bag if you choose to try the method. It must evaporate from the top of the bag.

Good luck!

[griff]

I would go back and take another look at the bracing...a very pronounced belly would either have to pull away from the brace or twist the brace...if the later isn't happening the former probably is. Also, the missing material under the bridge is very likely contributing to the roll in the bridge, it's a tricky job to re-build that area under the bridge, but it would be the correct way of restoring it. I would also replace the plate with an oversized one as well...the design you have drawn up is interesting, it might help. I wouldn't install the the bridge doctor. I have seen guitars come in that have had a cross strut glued behind the plate between the x brace arms...that might be an option as well.

[Ned Knepp]

Just out of curiosity, Giff, why wouldn't you consider using a Bridge Doctor?

[griff]

A pronounced deformation, like the one described here, indicates structure problems. there are a number of variables that contribute to a problem like this (most have been described in this thread), I think it pays to look into those variables first. For example, the J45 has a weakened area under the bridge from a past botched bridge removal, and a worn, narrow, inadequate bridge plate. If you jump to the bridge doctor without fixing those problems you're not just masking the root cause, your adding a load to an area that is already weakened. I could easily imagine the results could be a cracked top down the road. I don't know, I think the bridge doctor has its place, but with this instrument, there's a lot of other things at play, and its worth it.

[Ned Knepp]

Thanks for the answer, Griff. I agree with you that the top absolutely needs to be repaired properly. I mentioned a Bridge Doctor as an alternative to a bridge plate that was over sized and included finger projection into the belly of the guitar. I saw it as support for the completed repair, not a way to the make the repair. For myself, I would prefer installing a device that could be removed to gluing in an overly large bridge plate then finding that it effected the tone too much. I understand that the plate will probably need to be over sized somewhat anyway. I just have some doubts about the effects of a large plate and finger extensions.

[Rob Mercure]

Hey Ned,

I have to disagree about the bridge doctor option as I finally wound up using this on my Martin D-25K after a neck reset and much inspection, reinforced bridge plate, etc.. I spend long hours with various lights and mirrors and even a video camera (and a funkly little surgery scope that I friend from a hospital had) trying to find a loose brace or some other reason that the top bulged and since I could gently push and flatten it by hand after long resistance used the BD - which was recommended on this forum as I'd long dismissed it - and it worked "miraculously" and even seemed to either improve or perhaps "restore" some of the tonal quality. "Some day" when I may return to the issue and figure out why the top bulged as it defies common explanation but in the sort run the BD is inexpensive, effective, and easily removable (which many options aren't such as a thicker bridge plate).

Griff probably has more experience than me and perhaps better equipment and such but from the perspective of someone who plays and treasures my instrument and wants it to work again soon the BD, IMHO, is a great option. And I "test" removed it and the bulge seemed to have flattened some but I only left it off for a few days as I needed to play a gig but since I think that part of my issue is long term wood deformation the BD also serves as a "corrective brace" that might actually create it's own solution (knock on wood).

Rob