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Neck Bow.

Discussion in 'Luthier's Corner' started by popinfresh, Jul 5, 2005.


  1. popinfresh

    popinfresh

    Dec 23, 2004
    Melbourne, Aus
    Hey guys, I finally cut out my neck today on the band saw, first problem I've come across is that once I took the thickness out of the neck (made it 22mm at bass end, 17mm at headstock end, is that ok?) it's become a bit bowed.

    Is going backwards though, so If I had strings on it, it'd be pulling it back towards straight..

    Is this OK? Will it straighten up when I put the truss rod in?

    Thanks!

    BTW: It's a NT Thunderbird!
     
  2. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    I'd use a double-action truss rod, so you can add forward bow if necessary, in case the string tension isn't enough to do it alone.

    Also, can any of the luthiers comment, is it possible or advisable in this case to glue on the fretboard while the neck is held in a slight forward bow, to try to counteract the (warp) backbow?
     
  3. I guess that it depends to what extent it has bowed. The neck on my 8 string I'm building bowed after the neck profile was cut and the fretboard was on. The humidity here had changed massively, so I just waited for it to go back to normal and it went away. I was also able to check that the truss rod could correct this amount of back bow, which it did easily with about 1 turn.

    How high is the middle of the neck compared to a line running from the two ends?
     
  4. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Maryland
    Owner: FBB Bass Works
    Yeah, I would think how you will proceed would depend on how much bow there is and how radically the humidity changes in your area. Gluing in a little relief would certainly help to counteract the backbow that the neck seems to want to gravitate towards. But if you are at one of the humidity extremes in your area and the bow is minor, you may just want to glue it on flat and when the humidity subsides it will come to rest at a more hospitable level.
     
  5. popinfresh

    popinfresh

    Dec 23, 2004
    Melbourne, Aus
    Humidity is pretty low here, as it's winter. So I don't think it'l be chaning around much soon.

    It's not much of a bow (I don't think). Around 1mm or 2mm at the highest point.

    Should I still just put the one truss rod in there? What about graphite bars, or will they do nothing for backbow?

    Cheers.
     
  6. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Maryland
    Owner: FBB Bass Works
    One truss rod should do. Graphite will stiffen against humidity changes. @ 1mm, I'd probably go ahead and move on if you're using a double-action rod. String tension will probably take out the 1mm and then you can add a touch of relief with the rod.