Gibson A4 neck delamination...

[Ian Pender]

I have a beautiful, but neglected 1911 Gibson A4 mandolin on my bench, and boy, is it giving me some trouble. It seems like it spent much of its life in its case, drying out in storage somewhere. When I got it, it had a center seam separation on the top, a badly shrunken and cracked fingerboard, some missing inlay and peeling fingerboard binding, and, most worrisome, a neck that had come delaminated down the center. I fixed the center seam split, removed the fingerboard (actually, it practically fell off on its own) and repaired the crack in it, reglued the binding and then got to work on the neck. This mando has a three piece neck with a pearwood center stringer that is dyed to look like ebony. The neck had split on the right side of the center stringer, so I ran plenty of hot hide glue down in there and clamped it. After that was set, I reglued the fingerboard, reattached the hardware (the original tuner buttons and pickguard are still intact, and in immaculate condition!) and strung it up, to make sure that everything would hold, before proceeding with the inlay repair (the missing inlay was in the middle of the crack from the split neck, so I wanted to make sure all was well there before proceeding). Well, the glue up that I did on the right of the center stringer held firm, but the neck split on the left side of the stringer within 24 hours. No problem, glued it up, clamped, and let it sit about two and a half days before stringing it back up. It was good for a week, before it split again, roughly in between the two prior glue ups.

So, from what I've gathered, tthe dyed pearwood center stringers on these mandos have a tendency to degrade. However, I haven't been able to find a solution to this problem from anyone I've talked to thus far.

Now I need to be clear, it's not my glue ups that are failing. This neck seems to be failing all along the length of this somewhat rotten and punky center stringer. Come to think of it, it's possible that the original glue joints were fine, and the wood just failed in that area.

How should I proceed here? I'm all ready to fire up the glue pot in the morning, but if I keep this up, I'll basically be impregnating this spongy old wood with hide glue, which has terrible gap filling properties, so in this regard, my efforts seem somewhat futile.

I'm typing on my phone, so I'll keep this short.
Any ideas? How would you guys proceed from here?

[Frank Ford]

Thin viscosity cyanoacrylate is about the only stuff I've had any success with, if I can saturate enough in there.  That old dyed wood was a clear issue even before the Great War, and Gibson acknowledged it in their literature  shortly after, when they went to the big triangular neck reinforcement.

Most of the time I count on the peg head and the dovetail body joint to help keep things together, along with the fingerboard, of course.  Then soaking in as much CA as I can, I call it basically done.

Now, the peg head often is the source of the stress wanting to pull things apart, so I reinforce it with a solid insert - either a spline or a dowel, to resist the tendency to allow the spit to start downward.

Here are a couple of FRETS.COM articles on that reinforcement:

http://www.frets.com/FretsPages/Luthier/Technique/Structural/Broken...

http://www.frets.com/FretsPages/Luthier/Technique/Structural/Broken...

[Ian Pender]

I thought I had read everything on your website, but I guess I must have missed these two pages that you posted. Not hard to do, I suppose, considering the sheer volume of informative articles that you've posted there. I need to take a minute to thank you for the wealth of information that you've provided all of us with that site, as well as with this forum. I've learned so much from both.

I had briefly considered inlaying some sort of reinforcement in the neck underneath the fingerboard, but I figured that it wouldn't do much good that far from the peghead. I also assumed that gluing the fingerboard back on would strengthen the neck up enough to make the added value of an additional reinforcement underneath negligible. I thought for a brief moment that maybe I could put some sort of spline under the missing inlay before replacing it, since the inlay route spans the stringer (I'll upload a grainy cel phone pic of this, why not?), but it would have to be a tiny spline, and likely a very pointless spline. But it would have never occured to me to split the peghead in that manner in order to install a concealed dowel through the tuning post holes, that's absolutely ingenious! I worried for a minute about the overlay and back strap fracturing in a way that made regluing the tuner post holes unsightly, but honestly, the back strap split so cleanly the second time it cracked that my glue up was virtually seamless.
Thank you so much for this idea, I'll probably give it a go this weekend!

[Robbie Collins]

I realize this idea would be time consuming and maybe sacrilegious and devaluing, but how about replacing the stringer with a better wood?

[Frank Ford]

Time consuming, and requiring destruction of peghead overlay/inlay, but a good solid fix, for sure.  Personally, I HATE taking those dovetails apart.   With the fingerboard off, you can rout for maple or reinforcement that can be glued deeply in the center of the neck, much like Gibson's late triangular insert. 

[Robbie Collins]

I forgot about the headstock fascia. Ian's photo shows something too beautiful to sacrifice.

[Ian Pender]

Split, doweled, and hanging up to dry. So far, so good.