Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Tight neck pocket V.S. loose one????

Discussion in 'Luthier's Corner' started by KenToby, Sep 10, 2002.


  1. KenToby

    KenToby

    Aug 15, 2002
    My Tobias has an incredibly tight neck joint and my Precision Deluxe has a very loose one, however they both play and sound great.
    How important is this joint and should I shim the Precision to tighten it??

    Thanks
     
  2. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Well, here's a perspective I heard somewhere (maybe even on this forum?) that makes sense to me.

    If you have any gap *at all*, it doesn't matter much whether the gap is big or small, because as soon as you lose direct contact between two pieces of wood, vibrations can't be efficiently transmitted between them, since air acts as an insulator.

    I don't offer this as fact, but it would seem logical. If it's true, it suggests that the old tight pocket thing may be something of a myth, at least as far as tone goes. I do think the fit of the neck pocket says something about woodworking skills and aesthetics and attention to detail, but I'm yet to be convinced that it matters all that much for tone.
     
  3. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    Agreed. Vibration is only transmitted by, and joint stiffness is only supplied by, surfaces that are in contact. Missing by .005" would be the same as missing by an inch. So in a bolt-on with any gap, the vibrations are transmitted through the surface-to-surface contact between the back of the neck heel and the bottom of the neck pocket. In a bolt-on that also provides contact at the sides of the heel, some vibration would be transmitted there also, approaching the effect of a set-neck or through-neck, depending on how tight the contact is.
    Note that if the pocket is too tight, side-to-side, the body can crack due to the pressure of having a too-wide neck into a too-narrow pocket. I have seen this on two Warwicks, one used, and one new. The cracks probably developed after manufacture, if the body wood shrunk more than the neck heel wood (due to temperature or humidity changes).
     
  4. Razor

    Razor

    Sep 22, 2002
    Dallas
    So how does one "shim" up a pocket that is a little bigger than the actual neck?
     
  5. Luthiers disagree about this. Some say vibrations are transmitted only via the bottom of the pocket. Think of a Fender-type pocket: The treble side of the pocket is nearly non-existent, but the tone doesn't suffer.

    This is true and happens oftentimes. That's why it's important that the wood used has been dried appropriately.
     
  6. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    Wherever there is contact, vibration will be transmitted. Wherever there is not contact, vibration cannot be transmitted.

    I would never say that the tone of a Fender "suffers" because of lack of contact on the side or sides of the heel. But I would say that the tone is shaped by this manner of attachment.
     
  7. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    Are we talking about the sides? I mean, I guess I could fit a side shim, but it wouldn't match the curve of a rounded heel. I'm looking at a neck and body I bought for a project and the neck pocket is 1/32" too wide on each side if I split the difference. This doesn't sound like much, but it's quite noticeable to the eye. The neck on my $250 Yamaha fits better!?! I agree with the effect (or lack thereof) on tone, but what about appearance. I wouldn't want to buy an instrument that had neck pocket sides I could fit a playing card in, even if the tone was great. Just looks like poor craftsmanship.

    just my $0.02
    -RH
     
  8. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Maryland
    Owner: FBB Bass Works
    If the bass develops cracks, then the 1/32" gap starts to look like good craftsmanship. Even well-seasoned wood will expand and contract when exposed to extremes of humidity.
     
  9. RyanHelms

    RyanHelms

    Sep 20, 2003
    Cleveland, OH
    I feel better about going ahead with that neck fit, since you put it that way.

    Maybe I'll do a touch of light sanding on the Yammy neck pocket to give it some room.

    Would it be OK to use hide glue and fill the gap? Sort of a quasi-set neck bolt on?

    Anybody that does bolt-ons, what's your tolerance for gappage? I imaging a pocket routed right from it's intended neck heel is pretty snug.

    -RH
     
  10. Here's some stuff on bolt-ons. You can approach set neck structural integrity with inserts and machine bolts. True, only in the area of contact but this method of attachment can help a loose neck joint immensely. With four bolts, you can pull together at a combined strength of about 800 pounds per square inch with the right hardware.

    I've used a method of fixing my sometimes :rolleyes: inaccurate routing of neck pockets by setting the neck in resin like a gunsmith does with a barrel in a stock. This makes a 100% contact with all matching parallel surfaces and can makes for a hard, sonic friendly material to transfer tone to the body. Since this is a "perfect" fit, there IS the possibility of a swelling neck or shrinking body could do damage. However, this type of joint is not "too" tight as one would be that were to "crush" the fibers of the body wood around the neck in a "hammer fit" sorta way.

    My rule of thumb for a decent fit is if you can unseat the neck with a slight bump of the neck by the butt of your hand on the back. If it bends out but doesn't pop out - tad too tight. If it falls apart when you remove the bolts - tad too loose.

    Hope this helps.
     
  11. I'm of the opinion tha t a neck pocket needs to be perfectly flat, as does the neck heel, for the sound transfer to be optimal. That is also the surface that is being squeezed together by the bolts, so I am guessing that unless the sides of the pocket are putting some pressure on the heel of the neck, there will be little or no additional vibration transmitted. And, in sound transmission, any layer of stuff adds "impedance" to the transmission. It's harder for the sound to go through a layer of neck wood, then finish, then paint, then to the body wood. Seems to me like there should be only bare wood on the bottom of the pocket and on the heel of the neck.

    Just my CD$0.03 worth.

    BT
     
  12. That's what Godin does. :)
     
  13. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    I agree except -

    It is not necessarily harder to go through different materials. The change in resistance itself does not absorb energy, although it could possibly cause some reflection. It is also possible that a finish layer could transmit better than an equally thick volume of wood.

    I think I would rather have as many surfaces as possible have some kind of finish, so as to reduce the rate of moisture absobtion and release.
     
  14. If I remember my physics right, and that was some time ago, it is actually the difference in density of the materials that affects how the vibration is transmitted. If you're soundproofing a wall, layers of dissimilar materials are called for. If you're trying to maximize transmission, like materials and the fewest possible tightest joints are best. That's why sustain is greater on neck through basses. All other things being equal, of course.

    Are we nearing the end of useful information on this thread?

    BT