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Setup trick

Discussion in 'Luthier's Corner' started by nemo, Mar 17, 2008.

  1. nemo


    Mar 19, 2004
    Hello, I just want to share with you some sort of a trick I have been using when setting up a bass - maybe you know it or have something to say to it, so please feel free to comment.

    It concerns the neck and body joint - with strings on, after tuning to a normal tuning, I slightly loose the neck-holding screws - two or three turns, just slightly so that neck can so-so move, then I slightly move with the neck to allow it to settle in the neck pocket by force of the strings pull. Then I tighten the screws back.

    In my theory, this settling in the neck pocket should increase the sustain and helps the overall resonance. What do you think?

    I thought about doing the same with bridge-holding screws but didn't tried it yet.
  2. I would think it would put unnecessary stress on the threads in the neck being under string tension and manipulated while under said tension instead of being locked to the body so the whole assembly bears the stress, as well as the potential for creating wear and possibly elongating the holes in the body the neck screws pass through from the screw threads...moreso if there is significant gap between neck and body at the heel.

    I dunno, I am unsure if I see any benefit, but anything is possible.
  3. That scares me.

    it should be seated prior to tension being applied.

    Just my opinion - but if it works for you....
  4. DSB1


    Mar 8, 2006
    Sounds like your neck pocket is too loose.
  5. ZolkoW


    May 8, 2006
    Hungary, EU

    I think, the theory is not bad at all. IMO, this is the same thing, that happens to every bolt-on necked instrument, but in a longer period. you help them finish in shorter time.. yes, full string-tension, and loose screews are a bit scary :)
  6. nemo


    Mar 19, 2004
    The neck pocket is not loose at all. When screwed in normally without strings, the end of the neck is about 0.5 - 1 mm from the heel of the neck pocket.
    Loosening screws under string tension causes pulling the neck bottom to the full contact with the heel of the neck pocket in the body. That is why I think it helps resonance.

    As ZolkoW poited out, I believe too that this process happens naturally in a longer time in bolt-on basses.

    Normally the neck-body contact is kept due to the lateral friction tightened by screws.

    I believe that if neck heel is in full contact with the bottom of neck pocket, the force and resonance is transfered directly and perpendicularly rather than by lateral contact only and thus more effectively.
  7. luknfur


    Jan 14, 2004
    I'm no luthier but the loosened neck thing seems questionable. Inclined to increase slop in the scewholes/inserts/whatever.

    Before I ever did it to a bass, I'd rig a neck to a board, tork the screws and mark the neck on the board, then tune the strings up and see if the neck moves over a time period. I'm also no engineer but my guess is a 4-bolt neck isn't going to move anywhere regardless whether it has a heel to butt up against or not. But I've never done that so I don't know.
  8. SDB Guitars

    SDB Guitars Commercial User

    Jul 2, 2007
    Coeur d'Alene, ID
    Shawn Ball - Owner, SDB Guitars
    If you have a 1mm gap between the end of the neck and the end of the neck pocket, it sounds to me like your screw holes are misaligned, and your pocket route is sloppy. The neck should fit snug in the pocket, all the way at the end, *before* you insert the screws. Snug enough, preferrable, that once the strings are out of the picture, you can remove the neck bolts, and hold the instrument up by the neck and it won't decouple form the body. I would suggest removing both the strings and bolts, and checking to see if your neck joint is tight when the neck is all the way down in the pocket

    If the neck is properly screwed down, then it shouldn't shift in the pocket even under full tension. See, the strings are not simply "sliding" the neck toward the bridge. They are pulling on the headstock like the string of a bow, which causes it to arch upward (which is why we have truss rods).

    In the case of bolt on necks, this is *always* the case... which is why if you loosen the bolts, the neck will bow up perpendicular to the plane of the strings.

    I won't argue that good neck to body coupling is a good thing, but is there any quantifiable data to support this whole "perpendicularly vs. laterally" idea?
  9. nemo


    Mar 19, 2004
    If you loosen the screws just a little bit, say, half to one turn, just to allow the neck to shift, the neck will not bow yet, it will shift laterally down to the bridge.
    The length of such shift doesnt necessarily be like 1 mm, it does not need to be even visible, but the strings pull will just seat it better.

    I made some quick drawings to explain how I meant it:

    after seating:

    I am no expert at all, thats why I posted it here to hear some more qualified opinions.
    I would love to have someone with some tension distribution measuring instrument to prove the impact of such procedure.
  10. the holes in the body are oversize so the body will slip over time regardless of how tight you have your screws to begin with...

    to me, loosening the screws and retightening is unecessary...it will seat itsself...
  11. I would think a better option would be to shim the space between the heel and body, rather than slip the joint.
  12. I always loosly seat the neck then tap the bridge end of the body against a carpeted floor, then tighten the neck screws. If you have just enough screw tension to keep the neck from slideing back but loose enough that it will slide when tapped into place then it will be seated as good as it can get. That's pretty similar to what you are doing.
  13. SDB Guitars

    SDB Guitars Commercial User

    Jul 2, 2007
    Coeur d'Alene, ID
    Shawn Ball - Owner, SDB Guitars
    I can see that... it's doing it while under string tension that would worry me... There is a couple of hundred pounds of tortion on that neck when the strings are tuned up, and that can't be good to place that stress on partially tightened screws... I can see bad things happening.
  14. Greenman


    Dec 17, 2005
    Ontario Canada
    +1. Thro a strip of 50 grit sandpaper in there and your done. :D
  15. svtb15

    svtb15 Banned

    Mar 22, 2004
    Austin,TX - McKinney,TX - NY,NY, - Nashville,TN
    I play it all. Whatever works for the gig. Q+
    Great idea. But in fact many top name builders do exactly as you mentioned ... it does make a difference too.. and its cool that you figured it out on your own...

  16. nemo


    Mar 19, 2004
    Whoa, thanks for info! I am so proud of myself.. :D
  17. 202dy

    202dy Supporting Member

    Sep 26, 2006
    If the idea is to make a connection while the components are subject to outside forces then the results will be less than optimum. This is especially true when the fasteners and the components are of differing strengths. The screws can destroy the threads in the wood if assembly is forced or misaligned. The connections will always be better when the parts are assembled at rest. In the case of a bolt on neck, without tension.

    Slipping the joint for a quickie setup is a trick that is used by many factories/importers when doing a final setup before shipping a new guitar to the dealer. When the strings are changed it is typical that the setup will fail. Then the customer is faced with paying for a setup. The good news is that quite often sustain is improved. The bad news is sometimes the dealer ends up eating it.
  18. Makes no sense to do this in my opinion, but I will agree that overtime you may find that the screws will come loose on their own because they are constanly being played with. Going to need a little more of a turn so they will tighten.
  19. nemo


    Mar 19, 2004
    Why constantly? I do it only once I receive bass and that's it.
  20. nemo


    Mar 19, 2004
    I don't understand what you mean.
    By "slipping the joint" you mean the process I have described above?
    If the factories/importers do this procedure, why its effect would be lost when changing strings??

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