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Using Vs. Not Using Graphite Bar Stiffeners in Neck

Discussion in 'Luthier's Corner' started by Jim T., Feb 28, 2004.

  1. I searched under graphite bars, neck stiffening etc...

    My luthier told me that he doesn't believe in using them but with the myriad of questions I was asking at the time and wanting to give the poor guy a break on questions for awhile,
    I was wondering why some luthiers don't like/believe in them and why others swear by them.

  2. Tried them and also discovered they're not necessary at all.
    Also, I see them as added stability more than stiffening device.

    The stifness added is low in comparison of what you can achieve by working on fingerbaord material or others horizontal laminations.

    Wood selection is key for the neck.

  3. Thanks JP. Could you clarify neck stability vs. stiffening?
    Don't they work together, both climatically and string pull wise?
  4. Skips


    Feb 19, 2003

    I was just reading about this on another forum, and the general believe was that similar strength neck can be achieved from using ebony, cocobolo, or purpleheart laminates--however, these all expand at around 10X the rate of Carbon fiber with heat/moisture.
    But...you'd think you'd want them to expand at the same rate...
  5. Suburban


    Jan 15, 2001
    lower mid Sweden
    Stability would be keeping the form (i.e. not warp), while stiffness would be the resistance to bending and compression.

    the problem with stiffnes is, that you need the stiff material to be so far out form the bend center as possible. For a neck, that would be tha back of the neck and the top of the fingerboard. Usually, you find the graphite stringers embedded in the neck, close to the bend center, where they add more weight than stiffness.

    The ideal neck is infinitely stiff and infinitely light - yet playable! Hence, it will never exist. But it woud imply an H-beam with fingerboard and back as flanges, with more or less nothing in between. The flanges would be built from very stiff material.

    An ordinary neck will consist of some layers of wood, perpendicular to the fingerboard. This configuration is to have the heght of the laminate across the bend center. Good thinking. Another way is a lamination parallel to the fingerboard, where you can use very stiff wood for the fingerboard and back, and balsa (well, not really; say spruce) for the core.
  6. Thank you guys.
    My original intent was to have a graphite bar placed under the low B string on a short scale bass hoping that the extra stability would help the B to project a little clearer.

    Sounds like all of my other design considerations (angled peghead, through body stringing, ebony or bubinga runners.stringers, custom wound pickups and EQ selection would far outweight any benefit the carbon fiber rod/bars would?

    Could any harm/negative "benefits" ensue from using a carbon fiber bar(s)? Other than additional weight?
  7. Jim the graphit just under the B string is not a good idea IMO.
    This will not add what you think and IMO not worth any effort.

    Through body stringing never did something great to me but this is just IME.

    about the stability and strength question, well Suburban kinda explained it. Graphite will not wrap/bend due to moisture ot temp changes, that's stability. Now, where the stringers are, they don't had much stiffeness.

  8. Suburban


    Jan 15, 2001
    lower mid Sweden
    I just remembered this morning, that I have seen a neck where the graphite insert actually helps stiffness. French, of course. Vigier, to be more precise.

    A single graphite bar is not a very good idea. It will mean an off-set stiffness where you need it less! "Treble" strings have higher tension, so the neck will bend more on that side. Also, you want to have the resonance frequency of the neck well above any useful frequency of the strings (incl harmonics) to avoid dead spots.
    So what you need, is a slight off-set of the trussrod towards the treble side. And, if you use any, repeat: any, kind of stiffness improvement, it should be off-set as the the trussrod.
    To improve stiffness on bass side only, a singlecut will be the feasible idea.
  9. Thank you Suburban. I appreciate all of the tech info everyone's giving me here.

    My luthier wasn't going to use carbon graphite reinforcement (as I wrote earlier)but I was a little paranoid that I/we'd be overlooking an important or even vital new technological ingredient in pursuit of my short scale low B goal.

    From what everyone's said here, I can rest easy on that score!
    Gotta love it when things are simpler than we try to make 'em out to be! :)

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