Neck de-laminating - any way to fix??

Discussion in 'Luthier's Corner' started by wsal, Jan 31, 2013.


  1. wsal

    wsal

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    Hey guys
    I'm in the process of building a guitar (shhh) and I just noticed the neck has de-laminated itself along one of the glue joins from the top of the headstock down to the pencil lines in the photo. This is a bit of a disaster as it's a neck for an archtop, and I've already cut the dovetail and fitted the fingerboard extension which was a lot of fiddly work, and I'd hate to have to restart from scratch. Can it be fixed? I'm thinking along the lines of syringing CA or some other thin glue into the crack and re-clamping? I can't really see any solution involving heating up the glue to melt it and re-doing, as the fingerboard extension is already in place and would have to be removed as well, not to mention the dovetail being already cut (which surely couldn't be perfectly aligned for re-gluing.) In anticipation - the glue used was Titebond - never had a problem with it before
    Any help?
    Cheers
    Will

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  2. Phendyr_Loon

    Phendyr_Loon

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    I'd work as much thin glue into the split as possible and throw a clamp on it.
    Once the fretboard is on it will provide enough lateral hold so the laminate joints will stay together.
     
  3. Bruce Johnson

    Bruce Johnson Supporting Member

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    No happy answer here. You've got to fix it right. A delamination this early on means either the glue joint is weak, which means that it's weak all the way down, or the wood strips are unstable and are pulling away from each other. Or both.

    If you try to cheat it now, it's just going to get worse. It hurts to have to back up and redo the work you've already done, but it will hurt even worse to put all the work in completing the instrument, and then have the neck split. One of the greater Luthier frustrations of all is having a neck lamination come apart, after the instrument is all finished and painted. I've felt that pain, as have most of us.....

    Saw it right down the middle, taking out that walnut center strip. Resurface the two parts, making them flat without springing. Laminations should always sit flat against each other unclamped. Don't glue them up if you have to use clamps to squeeze them together. Reglue them carefully with a slightly wider center strip. That will give you a little more material, so you can retrim your dovetail.

    Also, before you saw it apart, drill a 1/8" hole crosswise through the dovetail. Then you can slip a dowel in there to get the strips lined up exactly where they were.
     
  4. Geoff St. Germaine

    Geoff St. Germaine

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    I'm with Bruce on this one. The entire glue joint is suspect and it has to be taken apart and redone in order to ensure you don't have worse problems down the road.

    As much as it sucks, it's fortunate this happened now and not after you glued the neck into the heel block. I'm building a trio or archtops right now and I'd hate to have that kind of problem at that stage of the game.

    Any pics of the archtop body to post?
     
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  6. Snort

    Snort

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    I am at an even later stage in my current build and a thought that goes through my head everytime I make a new cut, or route another pickup cavity, is the amount of time, effort and money already invested in the project which makes any mistake more costly. Unfortunately the further you get through the build the higher the cost of that mistake. So fix the problem properly before you invest more time effort and money into the build. So I fully agree with Bruce here, if you dont fix it correctly you will always have that risk hanging over you, and the instrument will always be less than you really wanted it to be. I agree cut down the defective glue join reface both sides and add another lamination in the middle. make sure all of your joints are square and marry together perfectly. I like Bruces idea of the dowel through the dovetail, of course you will have to clamp the new lamination to one side of the neck and drill it also.

    Good luck I hope it goes well and dont forget to keep us posted on the results, we can all learn from this.
     
  7. Bruce Johnson

    Bruce Johnson Supporting Member

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    There's a wise old saying from somewhere:

    Amateurs and professionals both make plenty of mistakes. The difference is that the professional sees the mistake quickly, and fixes it right then, before it gets any worse. The amateur doesn't notice the mistake until it's too late to fix, or ignores it and thinks nobody else will see it.

    Building high quality instruments is hard! There are hundreds of tiny ways that you can screw up and ruin a pile of previous work. Don't let it get you down. You just have to back up and do that part over again until you get it right. It happens to all of us.
     
  8. wsal

    wsal

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    Thanks for the replies guys! Geoff, the project is a bit of a hybrid - I bought a complete archtop body on eBay, old factory stock or something (as it has a pressed laminate top), and then I'm building the neck to fit. The end result will (hopefully) be a 7 string approximation of a Gibson ES125/L7 with a humbucker and old style hardware! Here's a progress pic from a while back - pre fingerboard extension/headstock wings.

    One other thing, which WAS a separate issue (but might now be the nail in the coffin) - the blonde timber is Victorian Ash (also known as Tasmanian Oak, perplexingly) and scattered here and there are these little voids - do you think they are of structural significance? My plan all along had been to fill and stabilise them with sawdust and CA, or epoxy. Now I'm wondering if maybe the whole thing was doomed from the start, and having to restart with new timber because of the glue split could be a blessing in disguise?

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  9. Geoff St. Germaine

    Geoff St. Germaine

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    It's hard to say if there's a problem. I'd only use wood that had no voids for a neck, but that doesn't mean there's anything wrong with the wood you have. If you think there's a risk then it's probably not a great sign, and I wouldn't continue moving ahead with a build unless I was absolutely confident in the structure of the instrument.
     
  10. pilotjones

    pilotjones Supporting Member

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    Are those checks (crack lines that open themselves up) in the middle of the neck beam board?

    If so, I don't like it. Not one bit. Checks open up due to lateral tension, which is being caused by tension, bending to torsion elsewhere in the piece. It's not just a cosmetic problem.
     
  11. Bruce Johnson

    Bruce Johnson Supporting Member

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    Those internal cracks tell you that the board has a whole lot of internal stress built up. Some of the wood is trying to pull one way, while the wood nearby wants to go the other way. This is typical of wood that came from a branch, rather than the trunk of the tree. The internal stresses build up from the bending loads caused by good 'ol gravity. These internal stresses are literally grown into the wood and, as long as it's a log, will mostly be resisted internally. But, when you saw it apart into smaller boards, the stresses get unbalanced. The wood bends, twists, and even starts cracking internally. Unfortunately, the unbalanced loading gets worse as you thin the wood down. The more you trim it down to the final shape of the neck, the more the remaining wood will bend and crack.

    Internal cracking like that is a big red warning sign. You probably shouldn't use that board for critical parts like neck laminations. If you really want to use it, the safest thing to do is to pre-cut the wood down to maybe 150% of the final size, then set it aside for six months or a year, and see what it does.
     
  12. reverendrally

    reverendrally

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    I've used Vic ash on 3 different basses now and never seen anything like that. It's tremendously strong and stable in my experience. I have come across little knot holes and sap voids, but haven't had dramas with them. I filled them with CA. Have you tried tried stressing the timber to see what happens to the cracks? Ie. do they open up more?

    Personally, if it were me, I'd put it on the shelf for 6 months and see what it does over that time.
     
  13. pilotjones

    pilotjones Supporting Member

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    I hadn't thought of the limb wood possibility, but it sounds right to me too. And, limb or not, those cracks are screaming out, "do not use in a neck."
     

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