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Thread: Neck fall away at 12th fret HELP?

  1. #1

    Default Neck fall away at 12th fret HELP?

    Is it normal for the neck plane to have some fall toward the bridge starting around the 12th fret? If the fingerboard were glued on it would probably be noticeable. The neck is dead on level until about the12th fret. Iím sure this has been discussed. But if some of you old dogs that know what your doing would chime in. It would take a load off my mind one way or the other. Thanks Gentleman!

  2. #2
    Registered User Steve Sorensen's Avatar
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    Default Re: Neck fall away at 12th fret HELP?

    No. You want the surface of the neck and fingerboard support dead flat for gluing across the entire length.

    Steve

  3. #3

    Default Re: Neck fall away at 12th fret HELP?

    What Iíve read about fall away toward the fretboard end. What does that mean and why is it discussed? Thx.

  4. #4
    Teacher, luthier
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    Default Re: Neck fall away at 12th fret HELP?

    Fall-away or fall-off means that the fingerboard is tapered downward, starting at somewhere between the 12th and 15th fret to the very end of the fingerboard. In other words, the board is thicker at the 12th fret than it is at the sound hole end.

    Very important: Fall-away refers specifically to the top surface of the fingerboard. The gluing surface of the neck itself should always be dead flat. The back of the fingerboard must also be dead flat.

    Conventional theory says a flat board should work.

    However, many classical guitar makers have been tapering their boards very slightly above the 12th fret [1/32" or so] for at least a century to avoid string slap. This can also be helpful on electric basses. On basses, the taper would start at the 15th fret.

    Steel string guitars must be evaluated on an individual basis. A small amount of fall-off above the body joint can sometimes take care of string rattling in the upper registers.

    Some electric guitars can also benefit from a little fall-off.

    On mandolins, a flat board usually works well.

    If there is a slight amount of fall-off, it won't hurt anything, but the player will have to push harder to get a clean sound on the highest notes. If there is too much fall-off, there will be intonation problems in the upper register.

    In new construction, if a board is tapered before it is glued to the neck, the back of the board must be perfectly flat; and the gluing cauls have to be designed to accommodate the fall-off.
    Last edited by rcc56; Mar-21-2020 at 1:52pm.

  5. #5

    Default Re: Neck fall away at 12th fret HELP?

    This looks to about .020 from the 12th to the end of the neck before the extension. Should I glue it up and then level the entire length of the fretboard of just leave it be? Thank you so much for the input.

  6. #6
    Teacher, luthier
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    Default Re: Neck fall away at 12th fret HELP?

    Looking more carefully at your original post, the neck plane should always be dead flat. I've edited my previous post to reflect this.
    True up the neck before you glue the fingerboard on.

    If we taper, we only taper the top of the fingerboard.
    Last edited by rcc56; Mar-21-2020 at 1:53pm.

  7. #7
    Adrian Minarovic
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    Default Re: Neck fall away at 12th fret HELP?

    How does the underside of fingerboard look like? Is it flat or is the angle already in there? What type of mandolin are we talking about?
    The only instruments that may need the fall off are acoustic steel string flattops (mostly guitars but other instruments of similar construction may need it too) where neck under tension can change angle slightly against top of body and without the fall off there would be a ramp instead of nice straight board.
    Classical guitars (built in the traditional way) typically have through neck and low-tension of strings and neck/ fingerboard geometry is meticulously built in during construction.
    Adrian

  8. #8

    Default Re: Neck fall away at 12th fret HELP?

    Thanks. This was a hand made F-style. The fretboard has been removed. The neck has a stiffener in it, no truss rod. The neck has not had any taken off other than to just clean up the glue. Checked with a straight edge, the neck is dead straight up to the 12th fret. It then falls about 0.20 from there to the end of the neck just before the cross piece. Fretboard support has not been installed yet. Any thoughts?

  9. #9
    Kelley Mandolins Skip Kelley's Avatar
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    Default Re: Neck fall away at 12th fret HELP?

    You’ve been given good solid advice. You want it dead flat. Since it falls away from the 12th fret to the joint, you could glue a small shim on the neck and then make sure the fretboard extension is sitting high enough that you can level the entire fretboard plane.

  10. #10
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    Default Re: Neck fall away at 12th fret HELP?

    Since it is a repair rather than new construction, it is a judgement call.

    In post #5, you said the fall-off is .020". But in your last post you said 0.20."

    You can probably live with .020", but if were me I would probably sand it out. But if it is 0.20", that is too much fall-off over a short distance, and that would have to be attended to.

    Either you will have to:
    1. Take wood off the entire gluing surface of the neck until it is straight and true, or
    2. Add a veneer to the entire gluing surface of the neck and true it up [If you use black and extend it over the support piece before you glue the fingerboard on, it will look like a 20's Gibson], or
    3. You can add a short piece of thin veneer in the offending area only and true it up.

    If you take the third option and are crafty enough, you might be able to hide the spot by pre-dyeing the edge of the short piece of veneer to as close a color match as you can get to the existing finish, then kiss it with a tiny bit of French polished shellac on a Q-tip with a thin cloth cover.
    Last edited by rcc56; Mar-21-2020 at 8:08pm.

  11. #11

    Default Re: Neck fall away at 12th fret HELP?

    That was a mistake. I meant .020. Be tough to shim anD feather that little I would say. Can I take it out of the fingerboard!

  12. #12
    Registered User Steve Sorensen's Avatar
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    Default Re: Neck fall away at 12th fret HELP?

    Most veneer is 0.02 thick, so a strip glued onto the low area past the 12th fret, then sanded to give a flat surface from nut to the end of the board works great.
    Been there done that.

    Steve

  13. #13

    Default Re: Neck fall away at 12th fret HELP?

    Thanks Gentleman! Strong advice. Appreciated.

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    Default Re: Neck fall away at 12th fret HELP?

    Iím continually amazed by the experience and expertise of those willing to contribute to the Cafe. Justrythym, youíve gotten some advice from some of the best in the biz...

  15. #15

    Default Re: Neck fall away at 12th fret HELP?

    In a perfect world, the neck is straight and the strings follow the neck. Easily achieved with a new build.

    In the imperfect world of repair and especially vintage instruments -- while a straight neck is still the goal, I would say fall away is preferable to having a "ski slope" at the end of the fingerboard. Fall away make it easy to adjust the action low up to that point, the upper frets being harder to play but in an area many people don't use anyway. OTOH, a ski slope makes it impossible to have low action anywhere and must be repaired, removed, replaned, etc....

  16. #16

    Default Re: Neck fall away at 12th fret HELP?

    Hey Jeff. Thanks for jumping in here. I checked this again. It is dead flat until the 12th fret. It then falls toward the cross piece. It is a tight .020 right at the cross piece at the end of the neck. More like maybe .018. When I hold the fretboard against the neck and site down it. It looks like you can see it just a little. If it makes any difference. Holding a straight edge on the bare neck plane and measuring the height at the bridge location, itís 20/32. Iím going to put big frets in this 55/95 because that is what my Son is use to. Looks like right now Iím going to be in the area of 3/4 finished bridge height. Thoughts? Thx. Man!

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