Lifting Bridges - Updated

[mlejeune67]

unclrob, no offense taken. 

I did notice a slight lifting with my naked eye before trying it with paper.  The lifting doesn't really show in the pics I took.  It is a thin sheet of paper, I don't think a thick business card would fit under far if at all.  Even if there's no glue there shouldn't it still be tight to the soundboard?  I wasn't sure what to think which is why I brought it to my dealer.  Was tempted to post here first but figured they would the final judge of whether it was an issue.  They seemed to feel it was an issue and I was happy to get it resolved now rather than later.  Of course I'm working under the assumption that it would worse.

[unclrob]

Theres about a post-its of finish above the cleared area for gluing the bridge.That said if you can see the lift I'd say get it popped and reglued.I glue it all down by which I mean I look for squeeze out of glue.

I'm glad no offence was takin

LV thanks for the pix.

[mlejeune67]

I just received my L-03R back from the dealer after having the bridge reglued under warranty.  As the OP I thought you might appreciate an update.

The repair looks really good and I can't find fault with it at all.  I spoke with the tech who worked on it and he couldn't find a problem with the join.  He indicated that it was caused by humidity.  I'm really confident that this guitar was properly humidified so this would have had to happen before I purchased.  This brings me back to my original question a bit.  How does this cause the bridge to lift if it's installed properly?

I also feel compelled to mention how well the dealer handled this.  They are part of national chain here in Canada and I'm usually not big on chains.  They are pretty much the only place locally where there's a good selection of Larrivees though.  They took this in on warranty without any hassle, gave me a very nice guitar from their rental fleet, shipped the guitar to a qualified tech at another one of their dealers, and had it back to me within a month.  They also adjusted the setup and filed the fret ends.  I think the tech even said he put on new strings.  All at no cost to me.  A happy ending.

[GA-ME]

IThe repair looks really good and I can't find fault with it at all.  I spoke with the tech who worked on it and he couldn't find a problem with the join.  He indicated that it was caused by humidity.  I'm really confident that this guitar was properly humidified so this would have had to happen before I purchased.  This brings me back to my original question a bit.  How does this cause the bridge to lift if it's installed properly?

Woods gain and loose moisture according to the RH in the surrounding environment and glue does not. When woods take on moisture they swell and when woods lose moisture they shrink. Since the glue really doesn't appreciably gain or loose moisture, once cured, something has to give and that someting is the wood.

[tadol]

Plus the one rule of woodworking that is by necessity broken in guitar building is that you never glue wood to itself at right angles. Wood expands considerably across the grain, but not at all along the grain. When building furniture, alot of effort is put into making any connections at right angles capable of floating. Look under any solid wood table top, for instance.

As long as a cross grain glue joint is kept at a constant relative humidity, it will be fine. But any changes that cause the top or the bridge to move - however slightly - will affect the glue bond. Add the tension or uplift pressure from the strings, and the back of the bridge will be the first place you'll see it. That's the main reason the complete removal of the finish from under the bridge, and the shaping of the bridge to match the contour of the top, are so important. You really want to get the maximum glue area and most effective bond possible - but you also want to be able to take it apart and re-do it relatively easily if you need to.

The fact that so many guitars get subjected to so much and are still holding together after many years of use is testimony to the skill of their builders, and the quality of their materials - but the need to reglue bridges ( or re-set necks ) is certainly not a knock on them, or the sign of a bad or problem instrument - 

Your re-glued bridge is probably stronger than a new guitars - I doubt you'll have any other problem with it.

[mlejeune67]

Thanks!  I think I understand better whats going on there now.  Really appreciate all the comments.