Straightening non truss-rod guitar neck?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by doc, May 16, 2011.

  1. doc

    doc Member

    Jan 26, 2005
    Middle Tennessee
    I have an old classical with a fairly thin neck that is bowed. I also have a newer Martin Backpacker with a non trussrod neck that has a slight bow as well. I'm planning to set them with fingerboard facing down supported by the nut and the place where the neck joins the body, then strap some weights to the middle of the neck, enough to create a significant back bow, and leave them for several weeks. Any other advice that won't cost me much money? Neither guitar is worth major surgery (like shaving down the fretboard and refretting, having a luthier remove the fretboard to install a truss-rod, etc.).
  2. sahhas

    sahhas Supporting Member

    Nov 8, 2007
    Imaginary land....
    don't know exact answer, yrs ago i was going to buy a friend's 50s martin, he said the neck had slight bow to it.

    i checked a local martin authorized repair place, they said they do something called a "heat set"-process where the neck is heated (someway) and they clamp it to a flat surface to straighten it.

    this was explained to me over the phone, i'm sure it's more "technical" than i'm describing. have never seen it done of course.

    didn't end up buying the guitar-not sure my friend really wanted to sell it...
  3. supergenius365

    supergenius365 Supporting Member

    Oct 22, 2005
    I thought there was a heat pressing process to do what you want. Are there no local repair guys by you to ask?
  4. memiller

    memiller Member

    Mar 11, 2011
    Grapevine, TX
    There is. Basically you take what looks like a piece of gutter and strap it onto your fretboard, plug it in, and wait. Maybe in a few hours the glue that binds the board to the neck will have released just enough and the neck will have straightened out. Unplug the thing, let it cool on its own, and you're done.

    I've never seen this actually work. Plus the neck and board have to be separate pieces.

    How much of a bow are we talking here? Fret the string at the first and last frets, then give a vague measure of how much space we're looking at.
  5. Sweetfinger

    Sweetfinger Silver Supporting Member

    Jul 16, 2008
    Phoenix, AZ
    Both of your guitars have truss rods- they are simply non-adjustable. Hanging weights or stuff like that isn't going to do anything because the moment you string your guitar back up, your hanging something like 180 pounds on it from string tension. I've never been a fan of the heat press. This will only work if you can "slip" the glue joint between the fretboard and neck, which won't happen in most modern or 'budget' guitars. Basically the wood will eventually go back to where it was.
    Sometimes an aggressive fret level/crown/polish can get you more towards where you want to be as far as playability. Are you using light strings on the Backpacker like it recommends?
  6. bunny

    bunny Member

    Nov 19, 2007
    Heating the neck is a VERY tricky thing to do and should be done by pros only. There are a few ways to straighten the neck without trussrod (or with a trussrod that doesn't work) Heating is only a part of the process and usually the frets need to be replaced too. Besides, heating will affect the binding, inlay and finish!
    In most cases I remove the frets, use the sanding beam (removing some wood closer to the headstock), install new frets and often level them also with the neck bow in mind.
    Sometimes the neck reset is the best way, and in some cases new frets with a thicker tang help to straighten the neck (differnt fret tang width in different areas of the neck can be used to correct the neck behavior). This is a pro pro job of course.

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