Regluing a bridge on a uke with no sound hole

As you can see from photo my uke does not have a traditional sound hole. I am loath to clamp the whole body. Has anyone successfully glued a bridge with superglue without clamping?View attachment 103885

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Here is a thread on another site that might be of some use:
http://www.classicalguitardelcamp.com/viewtopic.php?t=37165
Apparently it has successfully been done without clamps.

Maybe some of the luthiers around here will weigh in if they see this. There's also a builder's forum here you may want to check.

Most luthiers will tell you to NEVER EVER EVER use superglue or crazy glue, but instead either one of the variants of Titebond, or hide glue, and you may get away with Elmer's 'Wood Glue' or 'Craft Glue' but a 48 hr drying/curing time is what I have used in the past to repair my own instruments.

I taped off around the bridge area, sanded all the old glue off both the bottom of the bridge and top of the soundboard, then put a copious amount of glue in each, spread with a fingertip, then set the bridge in place and then put a stack of 5-6 encyclopedias on top and any glue that squeezed out, I removed with a dozen or so q-tips and then one pass with a damp paper towel around the edge of the bridge, and let it sit.

You need to put the books on top before the wiping off the squeeze-out, otherwise you will do the wiping at least twice.

During the time after stacking the books and wiping, you can verify correct placement of the bridge, otherwise your intonation will be messed up, and a 3mm wide saddle can only do so much to fix intonation issues...

The Titebond and Hide glues can both hold a bridge in place on a soprano (~13.75" scale) which usually has no more than about 27 lbs total string tension, AS WELL AS on sizes up to a baritone (~20" scale) which usually has no more than about 55 lbs of total string tension. Classical guitars have the bridges held on with nothing but hide glue for hundreds of years at a 25" scale length and about 100 lbs of string tension.

The briidge does not usually come off solely from glue failure, but due to the fact that the bridge and soundboard are made of different woods, which react differently to humidity, and thus will contract and expand based upon relative moisture content, this disproportionate wood reaction is what leads to the glue being released, NOT the bonding strength of the glue itself. Super/crazy-glue is likely to cause MORE damage to the top because the area under the bridge cannot expand or contract much at all now, and the wood around the bridge is more likely to fail, and thus causing a hole where the bridge used to be.

But I am NOT a luthier, and you will get professional advice as per suggested above by jer, by re-posting your question in this section of the forum:

http://forum.ukuleleunderground.com/forumdisplay.php?30-Ukulele-Building-Luthier-s-Lounge

also, there are tons of YouTube videos that demonstrate the procedure, and likely any done that recommend super/crazy-glue are NOT a pro, OR are put up by folks that have not done their research. Using the wrong glue means that you cannot easily remove or repair again if you mess up without extreme damage to the instrument due to the use of acetone solvents to release the super/crazy-glue.

However, it's your instrument, and you are free to do as you wish.

Hope this helps and best of luck

Without a photo I'm guessing for your instrument, but this is what I'd do if I built a uke with no sound hole.

All joints are best with full wood-to-wood contact, so I wouldn't weight down the bridge in place of clamping. This will almost certainly change the shape of the top, so you don't get a good fit and the bridge will pop off again in the not too distant future.

So step 1 is to scrape away all the glue residue on the top at the bridge footprint (I use a chisel held vertically) and on the underside of the bridge, so that you are glueing freshly exposed wood. This is the point where you (if necessary) shape the underside of the bridge so it fits the top with no gaps.

The glueing technique is what is called a "rubbed joint" - apply glue to both surfaces and then rub the bridge back and forwards a tiny amount (1/8-1/4 inch, 2-3mm) to force out the surplus glue in the joint. After a few seconds you feel it start to grab, and you make sure it's in the right place and hold it there with light finger pressure for about a minute. That's it, leave overnight for the glue to cure. You will need to clean up the glue squeeze out before it cures solid.

This works best with hot hide glue, but also works OK with Titebond too. Both these glues are reversible if you get it wrong, or if future repairs are needed.

Superglue is a bad choice, though I'm not saying it definitely wouldn't work. It's one shot (if in the wrong place then you're literally stuck with it), and makes future repair really hard. It doesn't fill gaps successfully, so you still need to make a good fit, and if you're doing that you might as well use a better glue.

Edited to add that I've glued a few bridges using this method and hot hide glue, and they all stayed on.

Well depending on how fancy your uke is, another option would be to use Titebone or hide glue, but also add a pair of screws to the bridge through the top. I have a Riptide laminate uke without a conventional sound hole, and there are two screws holding the bridge in place - though after you cover them with wood plugs you can't even tell they are there. The screws would certainly hold the bridge down well as the glue sets, and compensate for not being able to clamp the bridge down as the glue sets.

I would suggest to NEVER use screws to secure a bridge to the top of a uke. This is very poor technique and is to be avoided.

besley said:

Well depending on how fancy your uke is, another option would be to use Titebone or hide glue, but also add a pair of screws to the bridge through the top. I have a Riptide laminate uke without a conventional sound hole, and there are two screws holding the bridge in place - though after you cover them with wood plugs you can't even tell they are there. The screws would certainly hold the bridge down well as the glue sets, and compensate for not being able to clamp the bridge down as the glue sets.

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BlackBearUkes said:

I would suggest to NEVER use screws to secure a bridge to the top of a uke. This is very poor technique and is to be avoided.

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Well that "poor technique" point will be news to Gibson, who have been using screws to hold down the bridges of many of their acoustic guitars since the 1930s or so. Models like the J50 and J45. If you like, you could just use the screws as "locator" pins and then remove them after the glue dries.

You certainly are correct about Gibson using screws on bridge for many years. I have repair countless bridges from these guitars over the years and the screws make the damage worse. Better that the bridge pops off completely than to have screw holes tearing up the top as the bridge fails. This is my experience.

besley said:

Well that "poor technique" point will be news to Gibson, who have been using screws to hold down the bridges of many of their acoustic guitars since the 1930s or so. Models like the J50 and J45. If you like, you could just use the screws as "locator" pins and then remove them after the glue dries.

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BlackBearUkes said:

You certainly are correct about Gibson using screws on bridge for many years. I have repair countless bridges from these guitars over the years and the screws make the damage worse. Better that the bridge pops off completely than to have screw holes tearing up the top as the bridge fails. This is my experience.

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Just in case you (or anyone else with experience here too) check this thread again, and have time to reply, I was wondering:
Did the ones you repaired have just screws going through or were there bolts with nuts on the inside? It seems like if they had bolts with a nut on the inside it'd hold up a lot better. I took in a Gretsch Jim Dandy guitar recently that has bolts going through the bridge, but I can feel nuts on the inside at the end of the bolts, so there is some clamping action going on. I'm hoping that holds up better than just a screw through a top would and helps avoid tear out. This is an inexpensive instrument, but I do really like it.
I dabble in some primitive type instrument building sometimes (diddley bows, cigar box type instruments) so this info interests me because of that too.

jer said:

Just in case you (or anyone else with experience here too) check this thread again, and have time to reply, I was wondering:
Did the ones you repaired have just screws going through or were there bolts with nuts on the inside? It seems like if they had bolts with a nut on the inside it'd hold up a lot better. I took in a Gretsch Jim Dandy guitar recently that has bolts going through the bridge, but I can feel nuts on the inside at the end of the bolts, so there is some clamping action going on. I'm hoping that holds up better than just a screw through a top would and helps avoid tear out. This is an inexpensive instrument, but I do really like it.
I dabble in some primitive type instrument building sometimes (diddley bows, cigar box type instruments) so this info interests me because of that too.

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The Gibsons that I've seen did indeed have bolts with nuts, not wood screws. Some folks have removed them thinking it would improve tone, only to find out that the bolts were all that was holding the bridge down. I can't imagine the bolts failing, but it wouldn't surprise me with a wood screw. Which is why I suggested the idea of using the wood screw just to anchor things till the glue sets, then remove them.

OK, here is what happens when the glue fails and the small bolts holding on the bridge are the only thing left. You now have two small points of contact with the bridge to the top plate. The pull of the strings lifts the bridge and the bolts start to come through the bridge plate on the inside, and then the top plate. These two small contact points now start to deform the top and the top starts to bulge behind the bridge. What needs to happen before this starts is for the bridge to be removed and re-glued to the top, you can then put the bolts back if it makes you feels better. I've done this repair many times. I would never build using bolts on a bridge, bad idea IMO.

besley said:

The Gibsons that I've seen did indeed have bolts with nuts, not wood screws. Some folks have removed them thinking it would improve tone, only to find out that the bolts were all that was holding the bridge down. I can't imagine the bolts failing, but it wouldn't surprise me with a wood screw. Which is why I suggested the idea of using the wood screw just to anchor things till the glue sets, then remove them.

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Yikes. Thanks for the info!
Here's to hoping I won't have that problem on my instrument with bolts. Now I know what to look for.