How is the neck supposed to fit?

Discussion in 'Luthier's Corner' started by Matthew Bryson, Jun 10, 2005.

  1. Matthew Bryson

    Matthew Bryson Guest

    Jul 30, 2001
    I've read many times that when checking out new basses to make sure that the neck fits correctly in the neck pocket. But, how is it supposed to fit. Is it okay if there is a tiny bit of a gap between the neck and the body (on the bass side in this case) ...not much of a gap, maybe .025 mm

    How much if any gap is okay, and if it is a problem, what's the problem with it?

    Thanks for any help you can offer.

    *I'm not sure where to post this, but I thought this forum my be appropriate - mods, please move is necessary
  2. Suburban


    Jan 15, 2001
    lower mid Sweden
    Well, if you have a .025 mm gap...there is no "gap"!
    There has to be a distance between the body cavity anf the neck heel, just to make sure it can be installed (obviously). The distance must also be wide enough to accept some "moisture movement" when the neck and body reacts differently to variations in environment.

    If the gap was .025mm, I'd be worried. What happens when temperature and/or air moisture changes??

    Between .1 and .3mm would be just fine. If I can chunk in the .42 pick, then I'll worry, and inspect the instrument very closely. But then again: I'm kind of picky on neck joints. A .8mm gap could work just as well. The really important part for the tone transmission of the joint is not the side, it's the bottom.
    The bottom must be very flat on both parts, and the screws must not bottom out.

    This applies only to bolt-on bodies, of course. In case of any glued variant, any gap is baaad!
  3. Keith Guitars

    Keith Guitars Supporting Member

    Aug 25, 2004
    Woodstock, NY
    Builder: Martin Keith Guitars, Veillette Guitars
    I agree...the critical area for vibration coupling is the bottom surface, and the bolt(s).

    However, once there's*any* gap/airspace on the side, then
    the its size is more or less inconsequential with regards to tone. Your tone is not traveling through air, so .00001 mm
    or 1/4" are tonally equivalent. It's either touching, or not!

    That having been said, the side-to-side stability is affected
    by the amount of free space around the neck. However, I've
    played basses with large spaces on one side whose necks wouldn't budge, even with serious attempts. It's a case-by-case scenario.

    Just my two cents!

    Martin Keith
  4. joeviau


    Jul 9, 2002
    Rhode Island
    While we're here, I've a question about glue-in necks.

    If the neck pocket and neck fit are too tight, isn't there a possibility that the wood will swell from the moisture in the glue and cause a problem / disaster?

    I don't really know, I was just wondering.
  5. Suburban


    Jan 15, 2001
    lower mid Sweden
    The moisture in the glue is not enough to make the wood expand in any tangible extent. You need to moisture the entire plank for that (more or less).

    So, when gluing, there will not be any cause for disaster.
    Later on, if the wood is not sealed enough, the neck may take in moisture and expand, and eventually crack the body. This is known to have happened, but is not at all common.
    It doesn't go the other way, because when the body wood expands, the neck pocket strives to widen.