Official Luthiers Forum!

Hi everyone,

I have a guitar with the back partially unglued that I am about to repair. I haven’t had time to fully inspect it yet, but from what I’ve seen no braces seem un glued or damaged; the opening goes from the lower bout (near the block) to just before the waist on the bass side. The guitar is a Martin DCX1E and I’ve never done any repair like this before.

My question is, supposing that all the braces are fine, are there any guidelines, things to watch for, things not do to… that I should know before starting? My plan as of now is to try and clean any glue residue and make a good joint, put just as much glue as needed (I will go for titebond) and clamp it.
I won’t retouch the finish afterwards, the job is only about regluing the back plate to the sides.

Thank you for any feedback!

_________________
Olivier Gauthier
Montreal, QC

Did it take a hit, or did the joint just give way? If it took a hit, you may be in for replacing some kerfing. I see a lot of these with shattered kerfing. Sounds like you should be fine, the HPL sides and backs don't have the stiffness that wood has, so I ended up making a mold to keep them in alignment. I've used Titebond for the main gluing, and then touched up the joints with CA because they never seem to be exactly set, no matter how much I try.

Here is why most lining to back plate or top plates fail in spots. Poor joint clamping at original glue up or concentrated heat exposure. The real problem you face is getting rid of the old glue. i do not suggest you use two glues as mentioned. No glue hold well to old glue, few if any glues hold well to different types of glue, including CA. Ideally you need clean bare wood joint with new glue. The bond of PVA glue is a chemical bond not just a mechanical bond.

Thanks guys

Mark, yes it did take a little hit (I think it fell off a bench or something) and like I said I didn't inspect it a lot, but thanks for the hint, I hadn't thought about the lining

Michael, good thing you mentioned that

Thanks again

_________________
Olivier Gauthier
Montreal, QC

Michael, I agree with you on not relying on the 2 glues for structural support. The sides of those HPL guitars have a 45 degree chamfer on them, no binding. In my experience, no matter how careful I was there were 1 or 2 places where the chamfer didn't line up perfectly. I use CA glue like a drop fill finish repair and scrape them back to the original chamfer. The CA isn't structural.
If it took a hit, also look for any hairline cracks in the side. These guitars fleck and crack rather than dent. I've reglued about 15 of these, and most of them had damage to the sides that didn't immediately show itself until I started putting it into the mold. Good luck!

thanks guys! I glued it back together yesterday at the end of the day and won't be able to go back to the shop to check my work until friday (tomorrow morning)... I'm quite nervous to see how it will turn out! I am aware it probably won't be a perfect flush fit all the way around, but I think (and hope) i have taken all the needed precautions...

_________________
Olivier Gauthier
Montreal, QC