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As much as I hate to admit it, even with cauls and fastidious clamping, not all my glue joints are perfect. In this case, these sides are wavy and caused the problem.

Here, I am using a piece of .001 dental matrix strip (ask your dentist for a few) to check around the edges of the joint and…. “Oh crud! How did that happen?”



You could also use a feeler gauge for this. (BTW - a sheet of paper is about .004.)

And here’s how I fixed it. I placed some CA glue on top of the strip and ran it back and forth through the joint. Then I clamped it.


It worked! And it probably saved this build from having a weird buzz after completion.

Nice tip! I will bug my dentist for some of those.

CA on Mahogany may bleed into the wood and show in finish. The more I do this the less I us CA. I like Fish glue and Spectrum CP0101

tippie53 wrote: ↑Fri Jan 03, 2025 6:38 am CA on Mahogany may bleed into the wood and show in finish. The more I do this the less I us CA. I like Fish glue and Spectrum CP0101

Zoinks! I had a ton of issues with rosewood and shellac, but never dreamed that hood ‘ol mahogany would be a problem. I liked the fish glue (StewMac) when I used it, but failed to mark the date that I opened it. Maybe I’ll order a new bottle. I’m finally writing the opening dates on everything - time flies when you’re having fun.

we sell fish glue at blues creek guitars.
Glues are something that you want to be sure you are using the right ones.

in a nut shell
Fish glue
when in doubt do a test glue up you will know if its fine . Glue up wait 2 hr see if it pull wood fibers off when pulled apart

types of glues
Drying glues
these are hide and fish
once dried they are set can be reglued
curing clues
Tite bond
Pva ect
these are usually a 24 hr cure once cured you need to remove old glue to reglue
Reactive glues
CA epoxy
once set done I have seen them reglue to themselves often can be removed with solvent. Naphtha can take off epoxy acetone removes CA

Thanks John! Good advice.

Typical beginner I can’t see the forest for the trees.

On my current build, the top is now glued to the sides. And of course, I felt this was the perfect opportunity to figure out the mysteries of resonance and tap tones. So I took my handy dandy rubber tipped hammer out and tapped…

Boink boink - good
Boink boink - good
Boink boink - good
Boink -bzzzz - dangit! what in the heck was that???

….. Let me try again …..

Boink -bzzzz - uh oh…. This is not good.

I isolated the buzz to a couple of areas in the waist are that were not fully glued. You and I both know how fastidious I was in the gluing and clamping of the top, right? But visually, I was fooled. Even with magnification, they looked like closed joints. But when I probed with dental matrix band (as shown above) I confirmed several areas. I put a ‘goober*’ of fish glue on the metal band and flossed it repeatedly through the space between the kerfing/side and the top. Then clamped.

I’m not sure if the binding slot and glued binding would have covered up the issue, but it was sure nice to know about this in advance and attempt to correct it.

Lesson learned - don’t assume. Always check your work.
Note for next build: work even harder to make sure that the tucked brace fits perfectly - and then some. Pretty good, or even really good, is not good enough.

—————-
* A note on the terms in this post: a ‘goober’ is more than a ‘dab’ but not quite a ‘blob’. All of these measures are far less than a ‘dollop’.

Great tip with the dental strip. Such a clever way to spot those sneaky gaps. I’ve used a feeler gauge before, but the dental strip seems even more precise for tight spots.

I’ve had similar experiences with mahogany. It can sometimes bleed through and show up in the finish, especially with shellac. Just be mindful of the open time, and always test a small area first to ensure compatibility with your finish.

Keep up the great work; These little tricks really make a difference in the final build!

Great to hear that I am not the only one that has experienced the occasional glue joint malfunction. Thank you for the great reminder here to always check and inspect your work as you move along the build. No matter how thorough you attempt to be there can always be that gotcha.

Have any of you tried Old Brown Glue? I have found it to have a longer open time than hide glue, it stores very well in the fridge between uses and and is quite easy to use. I haven't tried fish glue but that sounds very interesting and I may give it a try.

Fantastic forum BTW! I'm a newbie here and while I have built more solid body guitars than acoustics the information here has me itching to get an acoustic build started on the bench.

Thanks!!