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View Full Version : bridge remounting advice sought



theabsurdman
09-29-2014, 11:25 AM
The bridge was lifting at the back and I took it off with the idea of refixing it with hide glue but a few problems became apparent:

- The wood has cracked slightly under the bridge all the way through to the inside.
- the body surface under the bridge is not flat but depressed slightly with a lip at the edge - looks like it could have been over-clamped.
- there is a lot of old gummy glue residue that looks like it could be epoxy.

Am I right in thinking the best way to go with this would be to scrape away as much of the old residue as possible, then use epoxy to get the strongest possible bond filling the gaps and stabilising the crack using the bridge as a splint? The crack is entirely contained underneath the bridge and the epoxy I have sets hard like glass so I hope it won't deaden the sound transmission too much.

It's not an expensive uke but nice enough.

Any other glues or techniques I should be aware of?

Thanks.

71389

Kent Chasson
09-29-2014, 12:24 PM
Based on the questions you're asking, I'd recommend taking it to a repair tech. I can't see the crack you're talking about but if it's just a bridge re-glue, it's an inexpensive job but one best done by a pro.

Based on what I can see.... If someone brought it to me, I would remove the glue, remove the top finish all the way to edges of the bridge, make a clamping caul (if needed) for the inside that spreads clamping force and is notched around the braces, and then re-glue with titebond or hot hide glue. It may also be necessary to sand the bottom of the bridge to better fit the top. A good fit is always better than trying to use epoxy to fill gaps.

Good luck.

Michael N.
09-30-2014, 12:46 AM
Not sure that is Epoxy but it needs removing. Little wonder the bridge came off with that amount of stuff sitting under it. You need a very sharp scraper. Wide chisels are good but even better is a small Plane blade, anything about 1" wide is fine. Remove the glue from both the bridge and the soundboard surface.
If there are gaps under the bridge the more usual procedure is to make the underside of the bridge fit the footprint of the soundboard. You can chalk fit it and test the fit with the thinnest feeler gauge - which is 0.05 mm's. Same scraper tool is used to make the fit.
If you are familiar with Hide glue you can reglue the bridge by just using light finger pressure and holding it for a few minutes, no need for clamps or cauls.

theabsurdman
09-30-2014, 09:32 AM
Thanks for the replies so far guys.

I could take this to a guitar tech but I'd like to have a go at fixing it myself, if possible.

I took another picture that I think better illustrates the problems. You can see the crack and the 'lip' where the top is no longer flat.

Removing all the remaining gunk will leave a gully and an exposed crack that would be very hard to match with the underside of the bridge such that it was flat wood-wood surfaces being glued and as much as I like hide glue, I understand that it isn't really that good at space-filling.

Is epoxy really a no no? Or is there something else I could use to use to fill the space and level the surface?

71411

Michael N.
09-30-2014, 11:14 PM
Strange how a change in camera angle tells an entirely different story. That's a real mess. The only reason that amount of wood should come off is with a top that has very short grain. Hard to tell going by the picture but perhaps someone was overzealous with scribing around the bridge and plunged far too deep with a scalpel. It's been done before. The other possibility is a previous botched repair. A few possibilities.
There are other ways to deal with this but they are long and involved. Approaches you would use on very expensive instruments and would be in the hundreds of dollars to correct.
You just might be better served putting the epoxy on and hoping it fills the gaps.

lauburu
10-05-2014, 10:28 AM
Yep. That's a mess. If it were me, I'd carefully rout out the glue from the low area, make sure the routed area is smaller than the footprint of the bridge. Glue in a veneer shim to fit the routed area, then sand level. Clean up the underside of the bridge then glue over the repaired area. Not the easiest of fixes but it should make a strong repair.
Miguel

theabsurdman
01-24-2015, 01:07 PM
I realize now I probably should have posted this to tech support rather than Luthier's but a quick update for completeness, as I finally got around to fixing this bridge.
I did use epoxy - v-tech 3 ton, which sets particularly hard - and (touch wood) it seems to have worked (so far). Thanks to everybody who replied.