Guitar body belling up

Subject: Guitar soundboard belling up
From: McGrath of Harlow
Date: 19 Dec 06 - 12:59 PM

I've noticed my guitar soundboard seemd to be belling up a little. It's the one in this picture. Not that much - it's still playable, but I'd hate to see it explode on me. I'm very fond of the guitar, which I found in a fairly bad state in a charity shop a few years back .

So I'm thinking what I could do to sort things. One idea is to fit on a tailpiece, so that instead of pulling up on the soundboard the strings would be pushing down.

Anyone ever tried doing that, and did it work out ok?

Subject: RE: Guitar body belling up
From: Mooh
Date: 19 Dec 06 - 01:42 PM

Harmony Sovereign? Depending on how bad it is, a bridge doctor might work (like the Breedlove bridge uses). Have someone reliable check the bracing, bridge plate, etc. Maybe lighter strings are in order, but my experience with tailpieces on flattops is that they don't help the sound at all.

Peace, Mooh.

Subject: RE: Guitar body belling up
From: kendall
Date: 19 Dec 06 - 02:45 PM

Gordon Bok plays a 12 string Apollo guitar with a tail piece. The reason for the tail piece is obvious, so much tension on the top of the guitar, but in this case it certainly doesn't seem to effect the sound. It sounds as good as my Apollo 12 which has NO tail piece.

Subject: RE: Guitar body belling up
From: breezy
Date: 19 Dec 06 - 02:59 PM

Sadly the situation will not reverse itself, it happened to my yamaha FG300.

bring it to the music Dept in St Albans, pete will sort it.

Bout time you got a decent guitar!!!

Hope you make my gig later next year at Stortfolk , I have a heap of new stuff.

Happy Christmas sir

Subject: RE: Guitar body belling up
From: Cluin
Date: 19 Dec 06 - 03:05 PM

Guitars with tailpieces have a different bracing system. If yours has a bridge plate, it was designed to be strung that way. It needs the extra tension to drive the top. You'd likely suffer some loss of volume and/or brightness. Also it changes the stress on the top from an upward direction to a downward one. It may make things worse and cause other problems.

Have you tried using a humidifier? The wood drying out often causes bellying up.

If you're worried (some bellying up is natural and to be expected and you'll have to have the action adjusted as a guitar ages), but you can try lighter guage strings to minimize the stress.

Subject: RE: Guitar body belling up
From: mandotim
Date: 19 Dec 06 - 05:21 PM

Hi! I recently repaired a mandocello using a Stewart MacDonald Bridge Doctor; a clever bit of kit that uses leverage to flatten the top. About $30 or so from StewMac, and very effective. It doesn't seem to hurt the tone, and playability actually improves, as the action is lowered and the intonation is corrected. Easy diy installation too. NFI, but strongly recommended. PM me if you need more details.
Tim.

Subject: RE: Guitar body belling up
From: leeneia
Date: 19 Dec 06 - 06:10 PM

NFI ? not for the intimidated?

Where do you store the guitar, McGrath? Perhaps it just needs moisture.

Subject: RE: Guitar body belling up
From: Ned Ludd
Date: 19 Dec 06 - 06:36 PM

If it's a made in u.s. Sovereign it may not be x braced. unfortunately it's an inherent problem with many of them. If the action isn't too high I'd live with it. If it is, then see a good repairman. A tailpiece will change the tone completely making the guitar sound toppier and more percussive.

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 19 Dec 06 - 07:32 PM

The guitar is probably late-sixties, an Angelica 3854, made in Japan, I think it's a Harmony copy. Not x-braced. I don't think it's a matter of needing moisture, I think its just showing its age a bit, like me.

I think I'll put the tailpiece idea on the back burner, and maybe try lighter strings - and also investigate that Bridge Doctor idea as well. Here's the website for it - looks like it'd be fiddly to install, but it might be worth it.

I've just PMd mandotim for advice on that. Anyone had any experience putting one in a guitar? And how did it work out?

Subject: RE: Guitar body belling up
From: Bert
Date: 19 Dec 06 - 08:04 PM

I have a guitar that did that pretty soon after I bought it bit it seems to have settled down now. I am keeping a close eye on it, but wont take any actiion unless it gets worse.

Subject: RE: Guitar body belling up
From: Bee-dubya-ell
Date: 19 Dec 06 - 08:38 PM

The Bridge Doctor sounds like a good idea, but one of these would be a lot cheaper.

(Insert insipid emoticon indicating "just kidding" here:________)

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 19 Dec 06 - 09:18 PM

I found an installation guide for the Bridge Doctor here. Well, it doesn't look too hard...

Subject: RE: Guitar body belling up
From: catspaw49
Date: 19 Dec 06 - 09:22 PM

Kevin, I put one of them on a really cheap piece of crap that a friend had......Long story, don't ask.......But it worked on it! And if it worked there I'd give you a fair chance at success!

Spaw

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 19 Dec 06 - 10:34 PM

That sounds encouraging. I think it might go on my Christmas List.

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 20 Dec 06 - 12:28 PM

Thanks for the helpful advice. I've decided to put in a Bridge Doctor. Now to decide which version.

There are two - one of them uses a hole drilled through the bridge with a screw, the other uses one of the existing pinholes, and replacing all the pins with brass ones with holes for the strings, and that's a good bit pricier, and puts the whole thing slightly off to one side, whereas I have a feeling it'd work better if it was dead centre.

The thing is, I've already got a screw through the bridge in the relevant place, and I could use that. But it's covered by a pearl plug, and I can't see a way of removing it so I can get at the existing screw to remove it. I'm reluctant to just break it out, in case when I remove it I find there's some problem with removing the existing screw.

Anybody got any crafty way for removing that pearl plug without destroying it?

Subject: RE: Guitar body belling up
From: s&r
Date: 20 Dec 06 - 01:02 PM

It's probably quite thin and just pushed in. Just flick it out with a watchmakers screwdriver, or a sharp pointed knife.

I've had guitars with rivets through the bridge, and with nuts and bolts. I assume they're used in assembly to hold the bridge while the glue dries.

Stu

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 20 Dec 06 - 02:22 PM

It took a bit more shifting than that - but the watchmaker's screwdriver did the job. And the screw came out with no problem. Good tip s&r.

Now my orders in, and I should get it in a few weeks. I'll refresh this thread and report on how it works out in due course.

I feel much more cheerful about my guitar now than I did yesterday. Thanks everyone.

Subject: RE: Guitar body belling up
From: DADGBE
Date: 20 Dec 06 - 06:47 PM

Removing that pearl plug usually isn't difficult at all. First, check to see if it is a screw or a bolt in the hole. (Bolts are easyest, screws are a bit more fiddley.) Stick your hand inside and see if you can find the nut on the end of the bolt or the sharp, pointy end of a screw.

If it's a bolt, find a socket that fits, then remove the nut. Now, take a coin in you hand and reach into the instrument. Place the coin on the bolt end and give a sharp, hard push on the bolt end. This almost always pops the pearl plug out along with the bolt.

If it turns out to be a screw, you'll have to break the pearl away from the top and replace it later. Most luthiers can supply you with the proper replacement pearl dot for a nominal charge.

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 20 Dec 06 - 08:45 PM

I'd tried that way, DADGBE, but it didn't do the trick - it was too tightly wedged. It's a well built axe. But the tiny screwdriver did the job OK.

Now, while I'm waiting for the gizmo to arrive, I'm taking the opportunity to give the stripped down guitar a good clean, for the first time in years. Scraping all the gunge off the fretboard and all. Maybe put some polish on sparingly, but I'm not at all sure about that.

With the strings off, the bellying has greatly reduced of its own accord. I'll stick a weight on top and hope that it reduces entirely before the Bridge Doctor arrives, which would make it easier to install, since I wouldn't need to be using it reduce the bellying.

Subject: RE: Guitar body belling up
From: Bert
Date: 20 Dec 06 - 11:50 PM

...I'm taking the opportunity to give the stripped down guitar a good clean, for the first time in years. Scraping all the gunge off the fretboard and all. Maybe put some polish on sparingly, but I'm not at all sure about that...

I do that all the time - Beats the hell out of practising.

Subject: RE: Guitar body belling up
From: Strollin' Johnny
Date: 21 Dec 06 - 04:44 PM

"Have you tried using a humidifier? The wood drying out often causes bellying up."

I'm sure you'll find it's the reverse - drying out causes the normal and perfectly acceptable bellying of the top to flatten, due to the shrinkage of the top. It bellies again when re-humidified (as happened to my Martin a couple of years ago - action dropped significantly and strings started fretting badly when top flattened after leaving it on its stand all (centrally-heated) winter, took it to a luthier who recommended humidification, kept it in the case for a couple of months with a PW humidifier, everything went back to normal, good action and no fretting).

Maybe yours has been over-humidified, McG?

Just my opinion, might be wrong and someone's bound to tell me so.
:-) :-)

Subject: RE: Guitar body belling up
From: Strollin' Johnny
Date: 21 Dec 06 - 05:08 PM

Should have also said that, with the humidification, the belly re-appeared (just like mine lately!)

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 21 Dec 06 - 06:47 PM

Fretboard should be cleaned every time you re-string: nylon scourers good!

NEVER use furniture polish nor any polish with silicon in.

Fingerboards should be treated with lemon oil, and only lemon oil.

Bodies can be cleaned (de-waxed, wax does not resonate well, try strumming a candle) with white spirit (at most, and try the spirit on a bit that doesn't show first, I once made a fairly major cockup with meths by ignoring this basic principle) and bogroll or kitchen polyroll.

Then damp bogroll or polyroll.

Then dry same.

Elbow grease is good.

Subject: RE: Guitar body belling up
From: catspaw49
Date: 21 Dec 06 - 07:54 PM

Typical paper towels create scratches and mineral oil works equally as well as lemon.

Kevin, before the thread goes off into the acquired myths of folkiedom, go visit one of the recognized experts in repair and luthiery, Frank Ford at Frets.Com.

Spaw

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 21 Dec 06 - 08:06 PM

Yes, I found Frets.Com for the first time today on my Internet travels, spaw - it's a brilliant site. I think I'd make a point of checking Mudcat suggestions there before trying them out.

But there's a fair amount of know-how out of the cat I've always found.   It's just a matter of identifying it.

For cleaning a guitar I've found a damp teeshirt is better than a paper towel or a bog roll. I've been using an old one from the Cambridge Folk Festival years back that is no longer up for wearing. An honourable and relevant retirement for it. And an old toothbrush is handy too. I don't plan to use toothpaste though.

Subject: RE: Guitar body belling up
From: Cluin
Date: 21 Dec 06 - 08:32 PM

Best cloths for cleaning/polishing guitar.... old cloth diapers (according to Dan Erlewine).

Subject: RE: Guitar body belling up
From: Scrump
Date: 22 Dec 06 - 05:33 AM

Dunno about your guitar, but my body seems to be 'belling up' at the moment - maybe it's all the mince pies, sausage rolls and winter ale at sessions. Is there a Bridge Doctor for humans?

:-)

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 31 Dec 06 - 12:04 PM

My package with the JLD Bridge System arrived yesterday, and I've installed it. This was very straightforward - a slight problem because the mounting post overlapped with a pin hole, but easily enough sorted out.

Then I strung up and was pleased to see that the bellying problem when the strings are at full tension appears to be sorted out. I had to adjust the bridge a little higher (fortunately it has adjusters built in), and fiddle around with the nut, to avoid buzzing - and then play it in a little. But now it sounds great. Louder and brighter than it did before.

Now I'm thinking I might get some more, and see if they improve other guitars I have lying around. I'd like to put one in a bouzouki, but I can't see how I could do that since the sound hole is so much smaller.

Thanks to mandotim for putting me on to this solution. And every else who chipped in. WhenI started the thread I had a horrible feeling I was going to have to retire my favourite guitar.

One bonus was that Stewart-MacDonald out in Athens, Ohio, from where I got the JLD, included a 94 page catalogue of "Everything for building and repairing stringed instruments". Some incredible stuff in there...

Happy New Year all!

Subject: RE: Guitar body belling up
From: catspaw49
Date: 31 Dec 06 - 12:50 PM

Here's another bonus Kevin.......Stew-Mac is a helluva' place and if you read about something or want to get a second (or 95th) opinion, let me know. I live just about 30 miles from them and I LOVE going there.....So if you give me a reason, I'll be there in a snap. ( I drive a red 2002 Snap sedan)

Spaw

Subject: RE: Guitar body belling up
From: mandotim
Date: 31 Dec 06 - 01:30 PM

Glad it worked! It's a really neat application of some very simple engineering.
Tim

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 01 Jan 07 - 08:48 AM

How much did it change the character of the sound of the guitar?

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 01 Jan 07 - 08:49 AM

oh, and, PS, did you get caught for import duy and VAT on the way in?

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 01 Jan 07 - 01:46 PM

Basically brighter and louder. A bit tight to start with, but that eased ioff with a bit of loud strumming. And I had to make a few adjustments to avoid buzzes with a lsightklyu lowered action.

No, they didn't charge import duty and VAT, so the whole thing worked out around £12 + postage, came to around £16 in all.

This site explains all about what's involved, and how it works.

Subject: RE: Guitar body belling up
From: dwditty
Date: 01 Jan 07 - 02:11 PM

I, too, have used the JLD bridge system - it is installed in a 12 string I have. Not only has it stopped the top from belly-ing, I can actually tune the thing now - and it has more volume and sustain that it did before. Best $50 I ever spent on a "repair." Nice folks, too...

dw

Subject: RE: Guitar body belling up
From: Seamus Kennedy
Date: 01 Jan 07 - 10:25 PM

Just curious guys - how about putting the JLD Bridge system in a guitar that's NOT bellying up to make it louder and/or brighter?

Seamus

Subject: RE: Guitar body belling up
From: mandotim
Date: 02 Jan 07 - 09:23 AM

Hi Seamus; not sure about this one, as to whether you'd get the full effect. Looking at the physics of it, I reckon the (undoubted) effect comes from three main sources; the first is that the top is flattened, and the bracing is therefore able to do its job properly. This should help the resonance of the top, and therefore volume and possibly tone. This would not apply if the top was flat already. Second source is the levelling of the bridge, which means the 'break angle' of the strings over the saddle is increased, which creates more pressure on the saddle, which means more efficient transfer of string vibration energy via the saddle into the top. Again, this would not apply if the bridge plate is already flat. Third source is the same as a violin soundpost, although in this case the 'soundpost' connects the bridge to the tailblock of the guitar rather than the back. This provides an extra physical conduit for vibration energy to be transmitted from the bridge to the rest of the body (as well as via the air in the body cavity and the top and sides of the instrument). This effect should still work. The only snag is that I'm not sure anyone has done the oscilloscope work to separate out the relative impact of each of the three sources, although I notice from the website that Breedlove are now installing these in new guitars. From my own experience (I've now done my own mandocello and two high-end guitars for friends) there is a marked difference in tone and volume; I wouldn't describe the tone as brighter, it seems to me to be 'clearer', losing the sometimes muddy mid-range that some guitars have. Overall volume is certainly increased. Hope this moves the discussion along.
Tim

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 02 Jan 07 - 10:08 AM

It seems likely to me that the shape of the vibration of the top of the guitar will be changed. A flat-top (pegbridge) guitar top is twisted by the string tension when played, so the vibrations will not be symmetrical (even if the top of the guitar were round and there wwere no soundhole).

With a Bridge Doctor, the twist is removed and the top acts more like a piston.

I expect this to reduce the harmonics. I expect this to make the guitar sound more like a tailpiece guitar rather than a pegbridge.

Subject: RE: Guitar body belling up
From: Seamus Kennedy
Date: 02 Jan 07 - 10:14 AM

Tim, thanks for the detailed reply.
However, I can't ascertain whether or not it would be beneficial to try it.
I see two 'no's' and a 'possibly' in your answer.
Both my guitar top and the bridge plate are level.
I do like the concept of the violin soundpost, and its application to a guitar, though.
I suppose the only way would be to try it and see what happens...
Looks like I'm the guinea-pig.

Seamus

Subject: RE: Guitar body belling up
From: mandotim
Date: 02 Jan 07 - 11:21 AM

Richard; good post! I hadn't thought in terms of peg bridge/tailpiece difference, but i can see how the Bridge Doctor (no relation I assume?) might act as a sort of internal tailpiece. Time to cover the top in iron filings and hit a low 'G'?
Seamus; if you do want to try it, remember there are two versions; one involves drilling the bridge, but the other uses replacement bridge pins, so the work can be reversed without affecting the guitar. In terms of whether or not to do it; I can only report that my experience was uniformly positive, and that Breedlove know a thing or two about getting tone and volume from guitars!
Tim

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 02 Jan 07 - 11:52 AM

There's no reason it shouldn't be fine with a guitar which hadn't bellied up. In fact with mine, after the strings had been removed and teh guitar rested it reverted to being level. The tension post should stop it bellying up again - it's installed in some guitars when they are constructed to avoid that happening, and to augment the sound.

As mandotim said, it can be reversed without any problem, if the changed sound doesn't suit you.

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 02 Jan 07 - 02:06 PM

One thing - the instructions end up: "Don't be afriad to experiement with the tension. It acts like the sound post in a violin. A small adjustment can make a big difference."

And I found that was quite true - to start with I had the tension rod screwed in a bit too tightly; relaxing it a little improved the sound a lot. That just involved slacking off the strings so I could get an Allen Key inside, ten seconds worth of adjusting using that, and then tuning up again.

Subject: RE: Guitar body belling up
From: ThreeSheds
Date: 02 Jan 07 - 03:12 PM

I cant see how a bridge doctor would be of any great benefit in a new guitar, as there wouldnt be a problem to correct.
Breedloves have them from new because it allows the guitars to be constructed with thinner tops ,so thin that they would collaspse without the bridge doctor reinforcement.
I suppose you could make an arguement for putting a bridge doctor in a new guitar, along the lines of that it was a form of insurance policy against the top never moving, but thats a bit like saying Martin et al dont know how to build guitars and that tops are best constructed from laminates

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 02 Jan 07 - 04:16 PM

After forty years or so I suspect any guitar is going to be liable to belly up a bit. And forty years is only middle-aged for a decent guitar. Guitars are multi-generational creatures, like giant tortoises or grey parrots.

But, even aside from that side of it, the tension rod/sound post, does affect the way the vibrations are transmitted from the bridge to the guitar, for the good I'd say.

I'd say it's worth trying, even in a new guitar. Nothing to lose really, since it's the easiest thing in the world to loosen, or even remove entirely, the tension rod, and to put it back or tighten it when desired..

I'm not sure whether I'm ging to tell all the guitar players I know about it, or keep shtum and let them be impressed by how my guitar is sounding these days...

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 02 Jan 07 - 05:09 PM

I built a sort of home-made equivalent to a bridge doctor (no, no relation) to go in a Framus 12-string I had been lent but which was unplayable due to extreme bellying. The Framus had a string-through bolt-on bridge (!) and so neither of the actual bridge doctor versions was going to fit. I clamped a large-ish wood block onto the inside of the top using dowel nuts (think Ikea) and the original holes for the bolt-on bridge. Then a Tee-nut on the blind side of that wood block enabled me to thread a bit of 6mm threaded rod up to push onto the tail block.

I'm sure this bodge is quieter than the guitar was, possibly because of the increased mass in the bridge area. I think my version is probably heavier than a real bridge doctor. I also expected the extra mass to decrease the resonant frequency of the top and so increase bass, but that didn't happen.

The problem was that with the threaded rod pushing and the strings pulling, the bolt on bridge tends to work towards the nut (it doesn't move once it's on so long as you do the clamps up to fart past grunt, it's just hard to get seated accurately).

To avoid filing long oval holes in the top of the Framus, I actually put a bit of shaped metal behind the original saddle to increase the tuning length and the octave is now about right.

It's a bodge. One day I'm going to take it to pieces again and do it right!

Subject: RE: Guitar body belling up
From: GUEST,Mac
Date: 29 Jul 08 - 09:53 AM

Richard Bridge said: "I expect this to make the guitar sound more like a tailpiece guitar rather than a pegbridge."

Which, I am afraid, only goes to show how wide of the truth expectations not based on empirical research can be. Try it sometime.

The effect of fitting the Bridge Doctor in my experience has been to increase both volume and mid-range tonal subtlety without any introduction of nasal tone, although it does take a couple of days for the top to settle down. Not an expectation. An observation.

BTW if you do fit one DO NOT over tighten it-- tighten the screw till the rod seats onto the tailblock (unstrung) then proceed slowly with 1/2 turn increments over several days. You'll get to a point where all is where you want it, bridge is flat, tone is good-- I would then back off a 1/4 turn and let it settle.

Subject: RE: Guitar body belling up
From: Richard Bridge
Date: 29 Jul 08 - 10:43 AM

Well, I also have two real bridge doctors, fitted to my 6 string and my 12-string Mugens, and I do think they have taken the shimmer off the sound a bit. I also do not hear an increase in volume.

Subject: RE: Guitar body belling up
From: McGrath of Harlow
Date: 29 Jul 08 - 05:53 PM

Most useful thread I ever started, from my point of view. The Bridge Doctor I put in back in 2006 is still doing a great job.

And one unexpected extra came with it - buying it put me on the mailing list for Stewart-MacDonald, and every now and then a fascinating catalogue from them drops through my letter-box.