truss rod-less neck

Discussion in 'Luthiery, Modifications & Customizations' started by foreright, Jan 28, 2021.

  1. foreright

    foreright SS.org Regular

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    Hi all,

    I'm after some advice as to whether two 4x10mm unidirectional CF rods would be sufficient in a 7-string neck to mean you wouldn't need a truss rod (leaving aside the matter as to whether this is a good idea or not, and I'm willing to concede that it's likely not...)? The neck itself will be a single piece bolt on made from korina with an ebony fretboard and not overly thin.

    My concern here is that if I went with that amount of carbon with a truss rod, it might be too stiff for the truss rod to work correctly. I usually go with two 4x4 CF rods parallel to the truss rod and have run into this issue before with a laminated neck. As stiffness increases with the cube of the thickness (ie. a little bit extra depth = a lot of extra stiffness!) that is kinda concerning.

    I have built truss rod-less guitars (acoustic) in the past but used some pretty substantial aluminium box section for those.

    Any opinions or is this a trial and error thing in reality?
     
  2. spudmunkey

    spudmunkey SS.org Regular

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    Only thing I have to offer: not all carbon fiber is created equal(ly).
     
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  3. foreright

    foreright SS.org Regular

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    Very true - maybe I need to do some experimenting.
     
  4. MaxOfMetal

    MaxOfMetal Likes trem wankery. Super Moderator

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    This isn't exactly unknown territory.

    Vigier does something similar with thier "90/10" neck construction, which is a mostly (90) wood neck with a big bar of CF (10) running down the center. In practice it works great, creating a stiff neck with just enough flex to allow for relief. Works just fine on thier 7-strings too.

    I'm sure you could workout exactly what forces you'll be working with relative materials, but they'll always be some trial and error to see what happens in the real world.
     
  5. foreright

    foreright SS.org Regular

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    Yep that is the kind of construction I was thinking about - guess I could work out the volume of the neck and check that I'm near enough to 10% CF. If the bar is in the centre of the neck rather than towards the edges it can be deeper too. Hmm.
     
  6. Winspear

    Winspear Tom Winspear

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    I may be wrong but it's my understanding that box section cf is better than solid of the same size? I intend to try a central 10mm box section with a 6mm box section either side
     
    Last edited: Jan 28, 2021
  7. pondman

    pondman Build Whore.

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    I dont see the point in not fitting a truss rod, its not a lot of work to do.
     
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