Help glueing a guitar

[scott spencer]

Need a little help from you experts out there. My son has an inexpensive Alverez RF-20 acoustic guitar....decent sounding guitar though. The bridge has lifted from the face of the body. I'd guess the bridge is rosewood and the body is spruce. We cleaned off the old glue traces and reglued with yellow wood glue and applied modest clamping pressure. The bridge lifted again within minutes of restringing. We stripped off the glue again, and retried using epoxy. This time it held for a day or two, but lifted again. I don't know what else to do. Any suggestions?

[john whittaker]

Scott...FYI - I'm not a luthier but my BIL is and...I stayed at a Holiday Inn Express last night...:rolleyes:

Anyway, he uses hot hide glue on his instruments. I also know that the top is supposed to be a little thicker and braced at the bridge location so it can take the extra pressure of the strings/bridge. BUT if epoxy didn't hold??? Maybe you need to make sure you sand down to bare wood before gluing. Pehaps you could make a block that just fits inside the body and use it as tempory bracing so you can put some clamping pressure on the bridge glue-up. (or wait for a real expert to answer your question)

FYI - I play a bit and think that Alverez, for a less expensive production type, makes a darn good guitar. (bang for buck)

Good Luck

[Doug Shepard]

Also not a luthier - but I play one on TV.
I've done some minor repairs on my own instruments in the past without screwing things up too badly. I'd also go the hot hide-glue route and scraping or sanding to bare wood. Epoxy could/should work, but what kind did you use? I've had the 5-min BORG stuff fail when other epoxies worked fine. The rosewood might need to be wiped with acetone first before gluing too. Before you re-try it though, I'd get hold of some of those wand mounted mini-mirrors and try to get a look at the underside of the top. Or tap around to see if any of them sound like they've come unglued from the top. Something makes me think you could have some bracing failure going on there. There might be a non-obvious reason other than glue failure why the bridge wanted to start lifting off in the first place.

[Norman Hitt]

Scott, (not a luthier either), and like others, played and had a small band, yearrrrrrrrrrrrs ago, and have made minor repairs. Do check the bracing underneath, as mentioned above, and ALSO, you will have to get ALL traces of the PVA removed, (SEE Bob Smalser's thread on repairable glue joints, as his tests showed that nearly NOTHING will stick to the PVA glue). Hot Hyde glue was "probably" the original glue used in construction, (but maybe not in the later generation instruments, as I have no recent experience with instruments).

[scott spencer]

Alright then you non-luthiers, I've approtiately retitled this thread! Thanks for all the tips. I'll check the bracing, scrub off the glue better, and look into hot hyde glue. ....now why didn't I think of that? ...oh yeah....no clue about guitars! :D

[Andrew Ault]

Scott,

How are you clamping it? I use extra deep clamps for this and sometimes a custom backer block between the clamp and the bridge plate (which is inside the guitar, under the bridge). I would usually use three clamps for this.

This is a highly stressed joint, as you know, so of any joint this one needs to be done carefully. Remove all traces of glue, acetone, scuffed surfaces, perfect clamping, lots of time to cure.

I use wooden cam clamps for this.

- Andy

[John Bailey]

Another non-luthier here, so take my comments with a grain of salt. I build dulcimers and have done some repairs on my guitars. All the other suggestions are appropriate in my view. I would add that I usually have little success unless I remove the offending piece entirely before I reglue. I would add heat and slowly pull the bridge off. That will allow you to carefully scrape or otherwise remove the old glue entirely. If the spruce below the bridge has a "lump" in the wood, it probably has braces that have come unglued. If that's the case, the sideways pressure will be higher due to the angle of force between the top of the guitar and the direction of the strings, and tend to lift the bridge. You must fix the bracing first. Again, not a luthier, but that's how I'd handle the situation.

By the way, my two guitars are both Alvarez-Yairi's and I find them to be some of the best no matter what the price.

John

[Vaughn McMillan]

It's been quite a few years, but I used to do guitar repair (among other things) in a drum & guitar shop. Andrew's advice is spot on. He's described almost exactly the things I've looked out for when I've repaired bridges on acoustic guitars. (Except I've used extra deep C-clamps instead of cam clamps.)

Ditto with John's advice. I'm assuming the bridge is all the way off the guitar. If not, it needs to be. As John mentioned, if there's a raised section of the spruce guitar top directly under the bridge, you should check and fix the bracing underneath.

To prevent marring the guitar top when removing the old glue, I've had pretty good success masking off the fnished surfaces with tape before scraping/sanding the old glue off. As others have mentioned, the bridge was most likely attached with hot hide glue, but I've had success reattaching them with yellow woodworking glue. As Andrew said though, it's gotta be a perfect joint.

- Vaughn

[Dan Forman]

I would second Norman's suggestion about looking at Bob Smalser's thread, here is the link. http://sawmillcreek.org/showthread.php?t=21822&highlight=epoxy

Just for the record, am a guitar player, not a luthier, but I've known a few, and they all used hide glue. I think this is due to the inevitability of repair at some point, so it helps to be able to take them apart when needed.

Dan

[Hank Walczak]

There's a lot of info at the Musical Instrument Makers Forum.
http://www.mimf.com/cgi-bin/WebX
I'm sure one of the threads addresses the issue.

Hank