Bridge Rotation

[Stuart Horsman]

A late 70's Guild has come into our shop for it's second neck reset in 18 mos. The bridge continues to rotate (pull forward)-despite adding minor braces to support the top, when we did the last reset. Has anyone had any success at curing the bridge problem? I would much prefer to solve this problem than remove the neck, again. Thanks

[Jeffrey L. Suits]

If the BRIDGE is moving, why are you dealing with the NECK?

JLD Bridge System. They work, I've installed 70-80 by now.

When you get the bridge back in alignment, you may have to deal with an overset neck.

[Stuart Horsman]

Thanks for the heads up about the JLD system. I'll chase it down, and see what it is. The only one I had seen was the "Bridge Doctor" and I wasn't overly impressed. Stuart

[Jim Bancroft]

I'd look for loose bracing inside. As long as all the bracing and bridge plate are in fine shape you should not have a problem with the bridge rotating. Also check for excessive bellying of the top, that may be a problem, but I doubt it. Maybe owner is using excessively heavy strings, but the guitar should take it, if it's structurally solid.

Jim

[Stuart Horsman]

I've checked the bracing, and the bridge plate (a little light, but okay). The owner uses light strings, so I knew that a neck reset would not cure the "problem"-which is why I'm trying to solve the bridge problem. Thanks for your help.

[Jim Bancroft]

As long as the bracing is solid, the instrument should be fine. Without seeing the instrument, the next item would be to reset the neck to where the bridge is. Otherwise you would have to do something to flatten the top. Possibly a new or slightly larger bridge plate.

When you say bridge rotation, I'm assuming you are referring to excessive bellying of the top???

Guitars all have different degrees of bellying. Basically if the guitar is structurally solid, even though it may have lots of bellying, I reset the neck to match the bellying and bridge location.
A guitar will reach a point where it won't pull up anymore. Being this guitar is strung with light strings, I can't see where things are going to get worse.

I guess I've never run into such an instrument, that was that structurally weak, that light strings was causing problems, especially if the guitar was originally designed for steel strings.
Good Luck
Jim

[Stuart Horsman]

Dear Jim,
Thanks for your help, and input. When we reset the neck, 18 mos. ago, we did as you suggest, and set the neck angle where the bridge was, but the bellying problem continues. This is why I'm trying to cure the problem at the bridge.... Stuart

[Mike Mancini]

Stuart, maybe the owner uses light gauge strings now, but he (or the previous owner) used heavier strings in the past that caused the top to belly excessively. I have a laminated-top beater guitar that had a really weak top that the bridge would rotate so much that it shortened the scale length, and eventually pulled the bridge off the top. I ended up having to put a spruce reinforcing plate under the bridgeplate.

Hopefully you wont have to resort to that but have you tried moistening the underside of the top and clamping it flat for a while? StewMac sells the Thompson Belly Reducer that looks like it would do the trick, although it shouldnt be hard to make one yourself. Then, after the belly flattens, maybe light gauge strings would help keep it under control.

On the other hand, I'm starting to thing that once wood "stretches", it gets a sort of memory and will eventually return to that state. The 1971 Martin D35 that I just overhauled had a weak top and the braces were not loose, yet it had a bad bellying issue like my laminated beater. I replaced the 1/4" straight braces with 5/16" scalloped and the top is nice and flat now.

Good luck and I hope to hear how you resolve this.
Mike

[Stuart Horsman]

Dear Mike,
As much as I dislike the idea of rebracing the top, I think that might be the longterm solution for this instrument. I am also considering a larger, heavier, bridge plate. Any thoughts? Several people have recommended the "bridge doctor," but I can't bring myself to install it on a nice instrument (cosmetics). You went to a 5/16 brace? I presume spruce? Thanks again, Stuart

[Jeffrey L. Suits]

You can fill the 1/4" mounting hole in the bridge, with either a tapered plug, or dust/superglue. I think you're referring to the one that uses the brass pins, which I don't care for, either.

This WILL flatten the top. I almost always install them for the volume/tone enhancement, as well as stabilising the top.

[Mike Mancini]

Yes, I installed 5/16" scalloped spruce bracing from StewMac. I replaced the X brace and the 2 belly braces (tone bars). The guitar is now a kind of hybrid D35/D28. The tone is much improved, and my pickin buddies agree.

A larger, heavier bridgeplate may help but at the expense of loss of some sound.
Instead, I would first try flattening the top with a clamp,as I suggested and using light gauge strings. If that doesnt work, maybe a reinforcing spruce plate would work, as Frank used at http://www.frets.com/FretsPages/Luthier/Technique/Guitar/Structural...

Both can be done thru the soundhole. If they both dont work, rebracing may need to be considered. But I heard that Guilds are built like trucks, so I'd be surprised if that would be needed.

I'm not a fan of the Bridge Doctor. I tried it on my laminated beater guitar and it didnt work. My guitar was so bad it bent the screw that secured the Bridge Doctor to the bridge !

[Jeffrey L. Suits]

"I'm not a fan of the Bridge Doctor. I tried it on my laminated beater guitar and it didnt work. My guitar was so bad it bent the screw that secured the Bridge Doctor to the bridge !"

Well, if something's that bad, what can you really expect?

This would be an inexpensive, functional fix for the OP's Guild, especially compared to rebracing and/or a new bridgeplate.

JLD's will need adjustment after un-bellying a guitar, and then you can get the top in equilibrium, for better tone. A guitar is not going to sound great, when the top is being pulled back into line, after years of warping, but after it take a set, it can be optimised. I use a strobetuner for this.

I always get a kick out of a customer's expression, when they play their first chord, after a JLD install; I like to do it with the same strings on the guitar, so the JLD is the only variable.

[STGuitarworks]

Hey Jeff,

I been a fan of the JLD for a couple of years now, I recommend it to customers, I install it on my own for the same improvement in vloume and tone...

How do you use a strobetuner to optimize a JLD?

Sean

www.stguitarworks.com