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Neck Relief

Discussion in 'Hardware, Setup & Repair [BG]' started by JPMo, Oct 11, 2013.


  1. JPMo

    JPMo

    Dec 27, 2010
    Canton, Ga
    So being the OCD perfectionist that I am, I decided to tackle the neck on my VM jazz. Action was a bit on the high side so I decided to straighten out the neck. Turns out my truss rod was maxed out so I'm at a road block. Is a neck without string tension supposed to have a slight bit of backbow or be fairly straight? I looked up some videos on youtube and saw somebody clamp the neck and apply pressure to the middle in an attempt to straigten out the neck, which I did. Right now the neck seems pretty straight but under tension will it just bow back up to being too high?
     
  2. It's supposed to backbow without string tension, if the rod has some tension on it. You should measure relief while it's strung up to pitch. Only then can you decide what measures to take. It may be that the neck is ok but needs a shim, for example. But measure relief first.
     
  3. Temezki

    Temezki

    Jul 1, 2012
    Finland
  4. JPMo

    JPMo

    Dec 27, 2010
    Canton, Ga
    ok Thanks. I dont think I need a shim because the saddles aren't bottomed out, but I'll keep that in mind.

    Yeah Im pretty sure its maxed out, I tried that technique but thanks for the help. That site is useful
     
  5. If it truly is maxed out (ran out of threads) you'll have to resort to the old washer under the truss rod nut trick. Simple, easy to do and works just fine. The only hard part is finding a washer that will fit.
     
  6. JTE

    JTE Supporting Member

    Mar 12, 2008
    Central Illinois, USA
    Measure the relief wit the bass tuned where you play it using the strings you use. Then you can start troubleshooting. Without the real data though, you're just randomly trying things. If the rod will not move when you attempt to tighten it, try this- loosen the nut to make sure it will move. If it does, then take the nut all the way off, put a VERY small amount of petroleum jelly in the threads of the nut. Make sure it's cleaned off and it's just a tiny amount inside the treads- just a very thin coating, you don't want globs (actually I'd use bicycle grease because I always have it around, but Vaseline is fine). Then carefully put the nut back on making sure the threads are engaged correctly and not stripping.

    Now, here's the thing. One should never simply tighten a truss rod nut. Pre bend the neck and snug the nut up. That way the nut isn't going to compress the wood because you're not making that very small diameter of metal force the whole neck to move. If it still won't tighten then either the threads are bunged up at that part of the rod, or your rod has run out of threads and you'll need to resort to the washers.

    But don't just start torquing nuts because the action is high. Find the real reason and address things in order. Make sure the nut is right. Set relief. Adjust saddle height to where you want it. Adjust intonation. If you can't get the action right and the relief is right, then look at the neck/body angle and shim as needed.

    John
    John
     
  7. The same amount of force is needed to keep the neck bent when you let go. Doesn't matter, with regard to wood crushing. But it DOES make for less friction on the threads as the nut is turned. So, still not a bad idea.
     
  8. JPMo

    JPMo

    Dec 27, 2010
    Canton, Ga
    Thanks everyone for the info!
     
  9. JPMo

    JPMo

    Dec 27, 2010
    Canton, Ga
    Well finished it up with some sunbeams and she sounds/plays great! I do prefer the sunbeams over the stainless rounds I had before any day!
     
  10. Rockin Mike

    Rockin Mike

    May 27, 2011
    Careful careful about maxing truss rods... I had one that I overtightened and it created an S curve that looked kind of like a forward-bow. Turns out when I loosened the rod the neck straightened out.

    FWIW I'm saying a "forward-bow" is when the rod is too loose and the strings pull the headstock forward. To me a "back-bow" is when the truss rod tension overcomes string tension and pulls the headstock back. An "S curve" is when there's both a forward and a back bow in different parts of the neck.

    On my "S curved" neck I was looking at the forward bow from frets 1 to 12, and ignoring the back bow above the 12th fret. I think they also call this a "ski ramp".
     
  11. JPMo

    JPMo

    Dec 27, 2010
    Canton, Ga
    Thanks I was definitely careful about not over-tightening the truss rod and I even had to loosen it some to get the string action a little higher
     

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