Fixing Cracked Neck Below Headstock

Discussion in 'Restoration & Repair' started by RobLM, Feb 13, 2017.

  1. RobLM

    RobLM New Member

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    I'm a beginner at repairs, and for practice I took a shot at fixing a cracked neck near the headstock on an old Fender DG-7 acoustic I picked up at a thrift store several years ago for $20. I have a couple of pics here (should have done a before and after, but didn't think about it) and am wondering if anybody has any feedback on how to do this better in the future. Here are the pics after the gluing and clamping, and below that, a quick description of what I did...
    upload_2017-2-13_19-1-13.jpeg
    upload_2017-2-13_19-1-38.jpeg

    The big inverted "U" crack was the first and worst of the visible cracks. What I did was:
    1. Set the guitar up vertically in a jig, then used a long board parallel to the fretboard with a clamp on the headstock and one on the neck below the crack to stretch the crack open a little bit for glue access
    2. Tried a couple ways to get hide glue into the crack as far as a could, including using a guitar string to get into the cracks a bit and also using a compressed air can to try and blast it down further
    3. Re-clamped to hold the crack shut.

    I am wondering a few things:

    1. You can see from the sideways shot that the neck below the crack didn't end up completely flush. Maybe this had to do with where I put the clamp (a little below this point). What could I do in a future similar repair to get it flush?
    2. Again in the sideways shot, you can see the cracks have spread into the binding at the first fret...is this likely to get worse in the future?
    3. Any tips on handling/maneuvering tiny chips like the one missing in the second picture? Do you just try to work it into place with your fingers?
    4. What else could I have done to make this a smoother-looking repair job?

    Any and all feedback appreciated!
     

    Attached Files:

  2. fumblefinger

    fumblefinger Member

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    Did you do any research before you attempted this? There are numerous neck repair threads here, on other forums and on YouTube.

    Anyway, the "U" shape is the scarf joint used to join the headstock and the neck. It wasn't a crack, but a delamination of the joint.

    1) When you clamped it up, did you use a caul that matched the shape of the neck? There are a number of ways to make one, but it is important to match the shape to get every fragment down flush.
    2) Just how hard did you tighten the clamps? Is it possible that in the process of clamping it, you caused the cracks to spread by overtightening the clamps? They should be firm, but not as tight as you can get them. You can overtighten them to the point that the wood is compressed past the original shape. Guess how I know? The other thing is that without knowing what the crack looked like, it's possible that there was a sliver that wasn't laying in the groove where it belonged. If it was across the grain, it could have held up the other side of the break and clamping forced the other side to bend, causing additional stress on the existing cracks. It's essential to make sure that any loose fibers are either removed or held back in place.
    3) The missing chip looks to be nothing more than finish. Drop fill it with whatever finish the neck has. Looking at the cracks, I'd assume it's a poly finish. If so, drop fill it with a medium CA. Same for the other cracks. Sand and buff.
    4) The hide glue is pretty thick. I'd have used Titebond I and thinned it 10%. Use a syringe to inject the glue into the cracks. If it has a truss rod, use a pipe cleaner to force some wax down the tr channel and on the tr itself. This keeps the glue from sticking to the tr. Then left it in the clamps for at least 48 hours. I don't see any glue squeeze out. Have you cleaned it up? If not, you didn't get enough glue in there. Again, hide is great stuff, but hard to work into a crack.

    I've attached a pic of the jig I use to lever up the headstock to open the crack, and one showing the syringe in place to inject the glue.
    Hope this helps.
    IMG_1453 1.jpg IMG_1455.JPG
     
  3. RobLM

    RobLM New Member

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    Thank you, very helpful! I did some research before the attempt but not much...since it's an old and inexpensive guitar of mine, I wanted to try and get as far as a I could without much help, to have somebody pick it apart to learn from the mistakes I made doing it on my own. I'll learn faster that way. In that sense, I think I succeeded :). Got a repair class coming up soon too, which is good because this was my only instrument that I would consider treating sacrificially in this way for learning purposes...

    I'm not sure how many people use this, but the hide glue was Titebond Liquid Hide Glue straight from the bottle, not the traditional heat-up kind. I think it might be a little thinner, but a little thinning would still have helped. Not sure if that stuff works as well as the traditionally used hide glue.
     
  4. fumblefinger

    fumblefinger Member

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    Hey Rob, if you're doing repairs to any of the usual woods used on guitars, Titebond I works very well. I've not used their hide glue, and I'm not sure if thinning it would have been the right thing to do. The good thing about both is that they can be separated with heat, so if the placement doesn't come out correctly, you have a second shot at it. You're right, experience is a great teacher. As long as it's your axe that you're working on you can chalk up any defugulties to your education. If it's a customer's, well that's another story...
     
  5. Tonedragon

    Tonedragon New Member

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    Tightbond, clamp then colormatch. I flood the plastic finish chips with CA glue. Then level sanded hit it with some tru-oil and buff. It's not always invisible to eye but it is to the hand. I then explain to the customer that their guitar is now about a 1/4 of what they paid , most scarf joint necks are strong but if they do break it's usually around that point. I then explain why they get made like a that in the first place.
    Lastly I suggest they order a guitar from me.
     

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