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Feeling the glue lines? They come and go.

Discussion in 'Luthier's Corner' started by rwkeating, Dec 19, 2017.


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  1. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    What is going on here and how worried I should be? For these examples I've used Titebond Original and for a finish, Watco Danish Oil.

    After gluing the fingerboard to the neck, I smooth out the lines where they meet so the joint can't be felt and apply the finish. After a few months of the instrument being done and a few temperature changes I can slightly feel the joint. After a while and other temperature changes, I can't feel the line anymore ... and back and forth it goes throughout the year. This also happens in a few spots on a laminated neck that I made (where the laminates meet) but so far to a much lesser extent.

    This isn't severe, but still ... I don't remember ever feeling anything like this on professionally made instruments. Is it because they use a finish that covers the wood and mask this very slight change at joints?
     
  2. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Unfortunately, that's one of the characteristics of Titebond. It expands and contracts with the weather, and will creep over time, like sinking at glue lines under the finish. That sort-of softness is a good thing for most general woodworking, because it helps joints stay together. But, we Luthiers are unusually fussy about how it all looks and feels up close. I like Titebond around the shop for all kinds of things, but I don't use it on instruments for those reasons.

    LMI's Yellow Instrument Maker's Glue is similar to Titebond, but it dries harder and doesn't move much. I use it on instrument joints where I don't want to use epoxy for some reason.

    I use West Systems epoxy for almost all structural joints on my own instruments. Strength and stability are the reasons. It doesn't break and it doesn't creep or sink over time or weather.

    A general note, regardless of the glue that you use: If the joint is tightly fitted, there should almost no glue line there. If you are seeing a line of glue that's pushing out and pulling in with the weather, that means there's a small gap which is filled with glue.
     
    rwkeating likes this.
  3. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    Thanks @Bruce Johnson. Is there a locally available, affordable glue that you would recommend for overall instrument building? I don't build enough to purchase large quantities of West Epoxy and depending on the on line place, shipping may be as much as the cost of a glue.
     
  4. T_Bone_TL

    T_Bone_TL

    Jan 10, 2013
    SW VT
    I'm reasonably sure you have a west marine near you, just like Nexy. I see quarts on the shelf there. 1160 N Halsted St, Chicago, IL 60642 according to the interwebs.

    Bruce, do you know if the (more expensive) 207 hardener lasts better than the 205/206 (unmixed), which you've mentioned as having shelf-life issues (more expensive if you use it slowly.)

    I found mention on a sailing forum from someone who said he'd been drawing down a can of 207 for 10 years with no color change, so perhaps it does. I also find that west claims the color going off in the 205/206 is purely cosmetic, and should not be a concern for strength (there's also mention of the possibility of the resin crystallizing, which can be solved by heating to 50C and stirring.)

    You could buy dual-tubes of Devcon (or whatever's handy) at the hardware store, but you'll soon exceed the cost of a small set of cans, I think.
     
    Last edited: Dec 19, 2017
  5. rwkeating

    rwkeating

    Oct 1, 2014
    Chicago
    none
    One more thing before this thread dies out. Should I be worried about the joints I've used Titebond Original on? I've also used it on scarf joints for headstocks.
     
  6. HaMMerHeD

    HaMMerHeD

    May 20, 2005
    Bruce, which West Systems epoxy set/kit/system do you use?

    I'd like to give it a shot, but they have a lot of options and I'm not sure where to start.

    I've used Titebond Original on every guitar I've made in the last 6 years, and have suffered no joint faillures.
     
  7. Beej

    Beej

    Feb 10, 2007
    Vancouver Island
    Oh man, the first few guitars I built, I made from old white glue that had been sitting on the shelf for years. No failures in any of the joints yet. I can't imagine titebond failing in that regard, but shrinkback? Yes... :D
     
    rwkeating likes this.
  8. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I use West Systems 105 Resin and either 205 Fast or 206 Slow hardener. For structural laminations, I go slow with the 105/206 mix. They go together in a 5:1 ratio by volume. You've probably seen my description in several other threads on how I mix small quantities of West Systems epoxy using my trusty Betty Crocker mixing spoons.

    I'm not saying that Titebond is bad stuff. It's one of the classic wood glues that's been around forever. It's easy to use and tough. But it has a few drawbacks like the shrinkage and creep. And it weakens at lower temperatures, which may or may not be a good thing.

    Good marine-type epoxies are stronger and more reliable than Titebond, and they don't shrink or creep. They also can fill gaps and can be sanded and polished. But they are more expensive and fussier and messier to use.
     
    rwkeating and HaMMerHeD like this.
  9. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    No, if the joint is fitted well, the Titebond should be fine. It's a good strong glue. You might get some creep or visible glue lines.
     
    rwkeating likes this.
  10. HaMMerHeD

    HaMMerHeD

    May 20, 2005
    Thanks Bruce! I actually tried LMI's instrument glue, but found the open time to be way too short. I did like how hard it dries though.

    Imma get some epoxy though.
     
  11. Gilmourisgod

    Gilmourisgod

    Jun 23, 2014
    Cape Cod MA
    I used Titebond on my Ric Build, now that it’s finish painted, I notice the neck beam/ body joint is faintly telegraphing through along the neck beam. I’ve seen this on real Ric’s too, so maybe it’s unavoidable because of basic wood movement.
     
  12. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Apr 10, 2021

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