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Extreme grain run-out? Curious neck failures...

Discussion in 'Luthier's Corner' started by reverendrally, Mar 16, 2018.


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  1. I came across this situation yesterday, after a friend of mine referred a work collegue to me with a broken neck on his acoustic guitar. The guitar in question is a 10yo Asian built Ashton. $150, so nothing exotic. Apparently a nice sounding guitar the owner was very happy with, even though he'd already had one neck failure and a PU failure. This is the pic he sent to me to ask about a repair...

    brokenashton1.JPG

    Here's a pic of the headstock... and a better close up of the break...

    brokenashton2.JPG

    Now here are the curious bits...

    1. This neck has broken before. You can see the old glue line from a previous repair (pretty ordinary repair I think, although effective for some years).

    2. Neither break resulted from a drop or impact. Both times, it just "popped" under normal string tension.

    From what I can see, it's regular old Mahoghany. What made me flinch was the way it had happened without an impact of any sort. Being stable for many years then just letting go spectacularly. Before you ask, no, it wasn't wearing super heavy strings. Just regular 0.013s". So all I can imagine is what we're seeing is pretty astounding grain run-out, in just the wrong spot. I guess that's a warning to any of us making one piece necks from cheapish timbers.

    The previous repairer refused to touch it on the grounds that even if they fixed it, it was a time-bomb and they'd have to charge him accordingly. I thought the same. Although the repairer did say you could glue it back together pretty easily and maybe have success, they just didn't want to risk it. I mean, you could rout channels and glue strips in, but not on such a cheap guitar. I gave him some advice on gluing it back together, but basically told him to buy a new guitar. He already has, but wanted to see if he could fix it for a spare. He's going to try gluing it himself.

    Anyhow, thought people might find it interesting and spark discussion about neck structures/techniques and help us all avoid such a catastrophic failure on something we love.
     
  2. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Not much to say, except that it's a structural failure. An engineering failure. The part was cut too small for the strength of the wood and the load being applied to it. It breaks right there, because the shape of the part is turning and going across the grain. The engineer in charge should have ordered them to put a volute there, to increase the depth of the beam. But the creative designer probably forbid it, saying it needs to be smooth and clean. And the project manager agreed, saying that the volute would increase the production cost by $0.05, which was unacceptable.

    Sure, it can be glued back together, but it will need some kind of reinforcement to keep it from breaking again. That work will cost some labor/money. But there are some cheap and simple repairs that you or he can do.

    If he isn't real concerned about how it looks, the simplest way to reinforce it would be to put a "Band-Aid" on the back of the repair. Glue the break back together, lining it up carefully. Sand the finish off of an area on the back of the repair, maybe an inch wide by 3 inches long, starting around the 1st fret, up an inch onto the back surface of the headstock.

    Cut a rectangle of cloth to fit. Ideally, carbon fiber cloth, but fiberglass cloth will work. Or rip-stop nylon, or some other cloth that has strong fibers and doesn't stretch at all. Saturate the cloth with epoxy and lay it on there. After it's cured, you can give it another coat of epoxy to fill and smooth it. Sand it to get a smooth surface and paint it brown. Do the job neatly, and it won't be too objectionable looking. It will be functional. It will act as a tension strap to take the load.
     
    Last edited: Mar 17, 2018
  3. BurnOut

    BurnOut It's The Billy Baloney Show Supporting Member

    Feb 1, 2015
    The Natti
    Justin Kennedy, somewhere on here does repair. His newest thing is using carbon fiber patch, along with a glue repair I'm sure. Finally covered with a matching wood cover. Beautiful repair work, seen his work on some high end vintage guitars. He does a most excellent job, takes his work very seriously.
     
  4. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    Vestal, NY
    Received a gift from Sire* (see sig)
    Love the not just "what and how" but "why" in your posts!
     
  5. Love to see a pic of that, if you can share one of his posts with us. :)
     
    BurnOut likes this.
  6. @HaMMerHeD posted this thread a while back. Probably more effort than you want to make on a cheap acoustic but interesting.

    Epiphone repair
     
    reverendrally likes this.
  7. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Yeah, I was going to link to that thread by HaMMerHeD too. That's the neater, more professional way to do the repair. He routed two slots and put in carbon fiber strips, covering them with wood.

    In terms of pure strength, the Band-Aid type is actually stronger because the added tensile fibers are right on the back surface. But it's uglier. With some care and black epoxy, you could make a neat looking shaped black patch.
     
    b3e likes this.
  8. BurnOut

    BurnOut It's The Billy Baloney Show Supporting Member

    Feb 1, 2015
    The Natti
    He hasn't been on here in a while, mostly post his stuff on FB. I grabbed a pic off his page, let's tag him maybe he'll pay a visit @ModulusAcacia
    FB_IMG_1521319091354.jpg
     
    T_Bone_TL, b3e, reverendrally and 2 others like this.
  9. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    Vestal, NY
    Received a gift from Sire* (see sig)
    Impressive! :thumbsup:
     
    BurnOut likes this.
  10. Christopher DBG

    Christopher DBG Commercial User

    May 18, 2015
    Westerly, RI
    Luthier/Owner, Christopher Bass Guitar
    I'm having trouble figuring out what I'm looking at. What is the deal with the light colored wood around the edge and the dark colored wood (?) inside? The light color is where the finish flaked off, but the dark?
     
  11. T_Bone_TL

    T_Bone_TL

    Jan 10, 2013
    NW Mass/SW VT
    Can't be sure with the size of the pic, but I think it's the back of the fingerboard. Or it's a weird angle and is truss-rod related?
     
  12. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    Vestal, NY
    Received a gift from Sire* (see sig)
    Yeah, the headstock is offset to the left from the broken end of the neck - that dark spot is the truss rod & channel. Took me a minute to "wrap my eyes around it", weird perspective I hope never to witness in person...
     
    BurnOut likes this.
  13. Bit of gaffer/duct tape and it'll be fine.
     
    4sight and BurnOut like this.
  14. Thumpin6string

    Thumpin6string Supporting Member

    Apr 25, 2013
    Redding CA
    I've done a not so kosher repair on a similar break on a cheap guitar. I glued it back together and after it is set, drilled diagonally through the break and drove in a hardwood dowel with glue. It bridges the break and you only have to sand the end of the dowel flush. With stain and finish, it looks almost like a knot.
     
  15. shodan

    shodan

    Mar 23, 2005
    Central Midwest
    No problem.
    Headstock Repair.jpg Headstock screws.jpg
     
    4sight, BritFunk, BurnOut and 2 others like this.
  16. shodan and Gilmourisgod like this.
  17. Christopher DBG

    Christopher DBG Commercial User

    May 18, 2015
    Westerly, RI
    Luthier/Owner, Christopher Bass Guitar
    @reverendrally , I was asking what the black is because I don't see any grain runout. Maybe it's mostly just a shadow I'm seeing, but hard to tell what else is going on inside there. That break looks like it goes across the grain at a 45 degree angle. A break due to grain runout would look like it followed the natural grain of the wood. @mapleglo posted a picture of a Fender neck she was thinking of buying a while back that had a broken headstock and it was a perfect example of a break due to grain runout. The break was clean, just like a split piece of firewood.

    I'll bet that neck is Philippine Mahogany and not Honduran. From the few times I had a piece of Philippine Mahogany it seemed lighter and more brittle, but can't say for sure less strong or likely to break. Pretty weird that it just popped off like it did.
     
    Last edited: Mar 18, 2018
    reverendrally likes this.
  18. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    Of course all this begs the question if ANY repair like this is cost effective on a $150 guitar. There must be 500 pictures online of Les Pauls and T-Birds with headstock breaks due to short grain in mahogany, that rises to the level of design negligence IMO, though I got a can of whupp-a** opened on me when I pointed it out on the T-Bird Club (big surprise!):D
     
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  19. T_Bone_TL

    T_Bone_TL

    Jan 10, 2013
    NW Mass/SW VT
    Hired out? Of course not, unless there's a big helping of sentimental value (which seems like it might apply to the Revs not-quite-customer.) Done by the owner, or the new owner that picks it out of the dumpster (and please, don't literally throw it in the dumpster - at least put it to the side and not too close to pickup day so someone else can grab it, or better yet, offer it up for free more formally) it can. Or it may serve as a springboard for some budding luthier to build a whole new neck, again, at more than the guitar is worth, but they gain the experience. Depending exactly where it's broken, it might lend itself to a headless conversion, too. Yes, I was alive in the 80's and still think headless is kinda cool.
     
    b3e likes this.
  20. b3e

    b3e

    Sep 5, 2017
    Warsaw, Poland
    Value is very subjective. Those east European 60s and 70s guitars, which believe me, were of nearly no value in the 80s for their crappy workmanship, bad pickups, horrible fretwork etc, are currently appreciated by some musicians for their unique sound and bumped up in value. Some things, on the other hand, dropped in value, like peppercorns, which for a handful of you could buy land and villages a few hundred years ago. Yes, it gave me some ideas on where to make money if I had a time machine ;)

    No matter how valuable it is from a market perspective it's still a guitar made of wood, which can make a musician happy or can grow the next Jimmy Hendrix, or a master luthier in the next decades. If I had it, I would probably fix it just for the sake of rescuing an instrument and trying out some techniques. If I had to pay for the repair, I would probably consider a replacement. Those techniques above though, would make me wanna try and even do it on my own :)
     

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