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Loose brace repair
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=53547		 Page 1 of 1
Author:  James Orr [ Fri Sep 25, 2020 9:26 pm ]
Post subject:  Loose brace repair
The last inch or so of one of my lower face braces came loose tonight on the onboard end next to an arm of the X as I was shaping it. I use a lattice in the lower face, and the guitar is at an easy enough stage at this point to simply carve the whole thing away and replace it, but I’d also like to take the opportunity to perhaps learn how to adequately repair it in case something like this comes up in the future.

It’s just barely loose, and I’m not sure how I’d get glue under it without prying it up a bit to open some space. Doing that, though, also seems like it comes with a risk of causing damage to the top. The only option I can think of is to wick thin CA under to chase the loose space.

How do those of you in the repair world approach this?


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Author:  phavriluk [ Fri Sep 25, 2020 9:43 pm ]
Post subject:  Re: Loose brace repair
Thin CA needs contact between surfaces to secure a joint. It can be flowed into place but needs immediate (like right now) clamping to create a solid bond. It won't fill a gap. Regular Titebond can re-activated with heat and clamped/pressed/held immediately, too. Glues can be gotten into loose joints by applying some to a clean feeler gauge and sliding the gluey gauge into where the glue is needed. Enough's getting left behind to do the job.

A picture would be real nice.
Author:  David Newton [ Fri Sep 25, 2020 11:10 pm ]
Post subject:  Re: Loose brace repair
I do lots of repairs like this, braces are always coming loose on guitars.
Heat the area from the outside and thru the sound hole with a blow dryer. Hot hide glue on a short-stemmed brush (or long stemmed, depending on your reach) is daubed around the joint, working the glue in. Rub all around the area with a rag to remove what glue hasn't sucked into the joints. To clamp the brace I use a strip of flexible wood (like birch) bent into a "C" or arc-shape and spring it against the back to the top brace.
Author:  meddlingfool [ Fri Sep 25, 2020 11:47 pm ]
Post subject:  Re: Loose brace repair
Sounds like it’s just a top and not a closed box?

I would create a gap with care and try to get some glue under, then just press and release over and over again until you see the squeeze out. Wipe off the excess and put it back under the go bars...
Author:  Clay S. [ Sat Sep 26, 2020 7:00 am ]
Post subject:  Re: Loose brace repair
One reason I like to use hot hide glue for braces is that you can "add" glue without having to remove the old glue. Although it doesn't wick in as much as CA it will wick in some if reasonably thin. Also you can pull some glue in by working the joint some (opening and closing it) while the glue is still hot and before it gels. The "gluey feeler gauge", as Peter suggested, also works well.
Author:  BobHowell [ Sat Sep 26, 2020 8:50 am ]
Post subject:  Re: Loose brace repair
I have had success with syringes forcing glue into cracks. Heat is a new idea but I have used it with veneer. New tip.
Author:  Alan Carruth [ Sat Sep 26, 2020 10:54 am ]
Post subject:  Re: Loose brace repair
Titebond and glues of that ilk are basically a 'hot melt' glue with a small amount of solvent that has been emulsified into water. The drops coalesce and harden up as the water evaporates. They soften at about 140 degrees F. It never occurred to me to use that to repair a loose brace, so that's a good tip. These types of glues are not really water soluble once they're dry, and won't bond properly to new glue the way hide glue will, so the heat repair would probably be the best approach.
Author:  phavriluk [ Sat Sep 26, 2020 11:09 am ]
Post subject:  Re: Loose brace repair
Opinion:

If OP encountered this bracing separation on one brace end, there could be others. I suggest he inspect all the others, especially if this is a top being assembled on a go-bar deck and there's access to everything. And if another is found, I think OP needs to take some time to consider removing the braces already installed and starting over using glue techniques that will not turn into some form of glue starvation. This problem is not one to rush past.
Author:  James Orr [ Sat Sep 26, 2020 1:00 pm ]
Post subject:  Re: Loose brace repair
phavriluk wrote:
Opinion:

This problem is not one to rush past.


I agree with that. I use a lattice, which has quite a bit of surface area. I don’t think it was a starvation issue as much as not getting the glue spread and clamped in time. I used HHG, and this little corned of the lattice was the last to get the go-bar placed. I think the glue may have gelled before I got good pressure down. After some inspection, the other areas are secure.

Last night, though, I did rush. I wicked in some CA because I wanted it to cover every bit of the surface and knew it would chase into every last crook. My only concern is whether it will hold up in the long run. What do you all think?

Image

Image


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Author:  wbergman [ Sat Sep 26, 2020 5:06 pm ]
Post subject:  Re: Loose brace repair
Regarding wicking thin CA, for what it's worth. I did center seams on a BRW ukulele by putting the 0.05" parts together tightly and then wicking in thin CA three times. Prior to this, I had tested the technique on scraps and found that a single wicking did not work, probably because the first application all sucked into the porous wood. So, maybe if you decide on wicking thin CA, run more than one application with drying time in between.
Author:  wbergman [ Sat Sep 26, 2020 5:07 pm ]
Post subject:  Re: Loose brace repair
Regarding wicking thin CA, for what it's worth. I did center seams on a BRW ukulele by putting the 0.05" parts together tightly and then wicking in thin CA three times. Prior to this, I had tested the technique on scraps and found that a single wicking did not work, probably because the first application all sucked into the porous wood. So, maybe if you decide on wicking thin CA, run more than one application with drying time in between.
Author:  Clay S. [ Sat Sep 26, 2020 5:35 pm ]
Post subject:  Re: Loose brace repair
James Orr wrote:
"Last night, though, I did rush. I wicked in some CA because I wanted it to cover every bit of the surface and knew it would chase into every last crook. My only concern is whether it will hold up in the long run. What do you all think?"

I think next time you may want to slow down a little and not rush the "redo". I've had situations where the first effort has failed to give the results I wanted. The nice thing about HHG is that even after the glue has set, with a little heat and water the parts can be separated if necessary, realigned, and reglued, without the need to clean off the old glue. With my recent travails regarding several old guitars that have come apart this has been a god send. Some have required regluing every seam, every block, and every tentalone making - me - at times almost come unglued at this sisyphean task. But it has been interesting to see how lightly built some of these old guitars are - sides at .050 in and backs at .075 in..
If you are committed to using HHG embrace it's virtues. They make it's drawbacks more bearable.
Author:  Alan Carruth [ Sat Sep 26, 2020 6:17 pm ]
Post subject:  Re: Loose brace repair
If you're using Titebond it can be thinned with water, up to about 10% of it's volume, without affecting the strength of the glue line noticeably. You do have to be more careful not to over clamp it, though. This extends the working time usefully. I use this in laminating veneers for binding and purfling. I was having the same issue of layers not sticking together well because it took too long to get the go-bars on.
Author:  James Orr [ Sat Sep 26, 2020 6:43 pm ]
Post subject:  Loose brace repair
I make a few of these lattices at a time, so I have two more on the shelf ready to go. I’m just going to pull this one off and do it right. Fewer worries that way. :) Is the easiest way to pop it off simply to work a hot pallet knife under?

Thanks for the thoughts and advice, everyone.


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Author:  bobgramann [ Sat Sep 26, 2020 9:18 pm ]
Post subject:  Re: Loose brace repair
When you’re using HHG, the heat gun is your friend. For that last spot where you think the joint might have cooled before you got it clamped, put a drop of water at the joint, spread it along the corner with your finger, and warm it with the heat gun until it feels warm when you remove the gun (ie, quick before it smokes). You might have been able to save it this way before the CA. HHG won’t fill gaps, but you can close gaps later with a drop of water and heat.

I went to using a brush on my braces for a while to reduce mess. I started discovering inconvenient failures. I’ve gone back to pouring it from a nozzle on a bottle. I have to clean up, but the thicker line of glue holds the heat better.
Author:  Terence Kennedy [ Sat Sep 26, 2020 11:05 pm ]
Post subject:  Re: Loose brace repair
I would really worry about using thin CA on spruce. I have never done it for braces but know from rosettes and binding that if the channels are not sealed with shellac it can wick into and discolor the wood.
Did you have any issues with it wicking through and discoloring the other side of the top?
Author:  James Orr [ Sun Sep 27, 2020 1:23 am ]
Post subject:  Re: Loose brace repair
Terence Kennedy wrote:
I would really worry about using thin CA on spruce. I have never done it for braces but know from rosettes and binding that if the channels are not sealed with shellac it can wick into and discolor the wood.
Did you have any issues with it wicking through and discoloring the other side of the top?


That's definitely something I considered, Terence. No bleed through thankfully.
Author:  meddlingfool [ Sun Sep 27, 2020 2:17 pm ]
Post subject:  Re: Loose brace repair
I’ve only had trouble with exposed endgrain, never on the flat...
Author:  James Orr [ Sun Sep 27, 2020 4:35 pm ]
Post subject:  Re: Loose brace repair
For the curious at heart, the CA is holding just as strong as the HHG right now as I’m cutting these braces off.

Image


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Author:  Terence Kennedy [ Sun Sep 27, 2020 6:30 pm ]
Post subject:  Re: Loose brace repair
When I glue braces with hide I usually heat the braces on a heating blanket and the plate with a heat gun. Run a good bead of glue down the brace with a squeeze bottle and go bar it on.

Usually lots of squeeze out cleaned up with a sharpened piece of spruce followed by damp paper towels and scrubbing with a toothbrush using hot water from the glue pot.

I hit the wood which is usually pretty damp with a heat gun after to dry it quickly but never thought about how that is probably reactivating any glue that might have prematurely gelled. Probably is.

Good info that the thin CA didn’t wick and is holding well. I think there was some guy here years ago that built a whole guitar using only super glue and it held together fine.
Author:  James Orr [ Mon Sep 28, 2020 1:01 am ]
Post subject:  Loose brace repair
Terence Kennedy wrote:
I think there was some guy here years ago that built a whole guitar using only super glue and it held together fine.


That was Kevin Gallagher, and I almost brought it up! That story was ultimately why I decided to use it the other night. If I remember correctly, he needed to get the guitar done for a show and built it in some ridiculous period of time—I think in a day or two.

Great tips, BTW. Thank you. I do think that kind of setup could really help with a lattice structure like this. Spreading the glue in time wasn’t too difficult, but getting a bar at all the critical positions within the remaining time before it gelled was.


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