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Thread: Is my truss rod broken?

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    Default Is my truss rod broken?

    I just got a new Kentucky KM-252. The neck appears straight but I wanted to add a touch of relief. When I took off the truss rod cover, the adjustment nut was all the way tight as far as it will go. So I turn it a little to the left to add relief but it has no affect. The nut is very loose and spins freely without adding any relief. The nut almost came off at the end of the threads and still didn’t add any relief. Am I not understanding something or is it broken?

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    Default Re: Is my truss rod broken?

    I assume it's a single action truss rod. Tightening it will pull the neck back to reduce relief/forward bow. Loosening all the way will result in whatever forward bow was built in, which may be very little. I suppose leaving it loose may result in some addtional relief due to string tension over time.

    I also assume you're taking the tension off the strings while adjusting. After you backed it off, did you tune up to check your relief?

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    Default Re: Is my truss rod broken?

    Oh…single action truss rod! I guess I’m used to the double action truss rods on my guitars. So it’s not broken, it’s only going to have whatever natural relief it has when the nut is loose. There’s also no resistance when screwing the nut all the way tight as far as it will go. The nut slides easily up and down the available threading having no affect either way. That’s normal?

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    Default Re: Is my truss rod broken?

    Quote Originally Posted by bbaker2050 View Post
    So it’s not broken, it’s only going to have whatever natural relief it has when the nut is loose.
    Not exactly: It’s going to have whatever natural relief it has when the nut is loose =and= the strings are putting tension on the neck. Parker's question of "did you tune up to check your relief?" is important but still unanswered.

    Quote Originally Posted by bbaker2050 View Post
    The nut slides easily up and down the available threading having no affect either way. That’s normal?
    Not normal, but not uncommon on more "ecomony" instruments. I would not have expected that on a Kentucky, even a lower-level one. (I once fixed a friend's Sigma -Martin import- guitar by adding several washers under the trussrod nut, which was bottoming out on the end of the threads.)

    It's possible that the rod is gunked up with glue that's preventing it from moving. I'd first tune up with the nut still loose and see if that pulls the neck into some relief. Maybe overtune by a note or two, or try heavier-gauge strings, to do the same. Maybe some "hand-messaging" to bend the neck into relief, while breaking any glue tension.

    And/or take it up with the seller. If it was a Cafe sponsor, they tend to be very good with such issues.
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    Default Re: Is my truss rod broken?

    Yes, I’m tuned up to full tension and there is still no relief with the nut loose. I bought it from Musicians Friend thinking I could do the setup.

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    Default Re: Is my truss rod broken?

    Your rod isn't broken. You have a stiff neck (usually a good thing) that may not have enough relief planed into it from the start (not so good). I would leave it loose for a while and see how the neck responds. Be aware that the nut and rod may vibrate a bit when loose. Also, on a single action rod there is not way for glue etc. to gum up the works if the threads are clear. One more thing, most mandolins are set up with very little if any relief. The smaller, higher tension strings don't need much relief to keep a good action.

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    Default Re: Is my truss rod broken?

    As others have said, wait a bit with the nut loose and see what happens.
    I always barely snug the nut in situations like this to avoid buzzing from the nut (and sometimes the rod) being loose and free to rattle.

    My question is:
    How are you checking the neck for straightness? A common and convenient way to do it is to use the strings as straight edges. Press a string down to the first fret with one hand and to the 12th fret with the other. If the string does not touch the top of every fret in between the neck is not straight. High frets will show up if the string is touching them, and neck relief will show up if the is slight clearance between the string and the fret tops.
    Sighting the neck for straightness is notoriously unreliable because of various vagaries that can fool the eye (like binding issues, variability in fret end treatment, differing reflections on various frets, etc.)

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    Default Re: Is my truss rod broken?

    It may take a couple of days for the neck to move. I don't put relief in mandolins, not the same as guitars. I have very low action and no relief and love the way it plays.
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    Default Re: Is my truss rod broken?

    Yes, I’m pressing 1st and 12th fret. The strings touch across all of the frets. Sounds like my neck is straight. Maybe I’ll just not worry about it! Thanks so much for your help!

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    Default Re: Is my truss rod broken?

    Unless the neck is made from seriously curly maple string tension should pull some relief into the neck eventually with minimal tension on the rod. You should be able to play it with the straight neck in the mean time.
    (Extremely curly wood can cause back bow in a neck, or prevent proper forward bow, but that is a very unusual situation in mandolin necks with their small profile and high string tension.)

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    Default Re: Is my truss rod broken?

    Has this instrument been setup yet? Have the frets been tap-checked for seating, and then leveled?

    If not, you really won't know for sure that there is no relief until that work is done...

    But, the recommendations to wait a bit on this, to allow the truss rod under string tension to break free from errant glue spots, are right on target.
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    Default Re: Is my truss rod broken?

    Hi Don….I was trying to do the basic setup myself (relief, intonation, action, nut slots), but no, it hasn’t had any fret work done.

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    Default Re: Is my truss rod broken?

    Quote Originally Posted by bbaker2050 View Post
    Hi Don….I was trying to do the basic setup myself (relief, intonation, action, nut slots), but no, it hasn’t had any fret work done.
    The recommendations to wait for a week or so for the string tension to affect the whole instrument are good... But after that, the frets should be tap-checked for seating and then leveled. Anyway, at that point you should be able to see about relief.

    Less-expensive brand new mandolins tend to have fret problems out of the box as a result of less detailed Q/A and shipping. The lower action involved with mandolins tends to accentuate fret problems more than other fretted instruments with longer scale lengths.

    Fret seating and leveling is something that can be managed at home by handy folks with the right tools, but it is typically done much better by an experienced setup person or a luthier. That said, fretwork and truss rod adjustment are just a few of many details that are part of a good setup, and with most professional setup people the cost is very worth spending at the beginning, before a player becomes frustrated with a difficult-to-play instrument.

    FWIW, a number of the best mandolin dealers include a high quality complete setup with the purchase cost of their instruments. While Musician's Friend often offers excellent prices, setup is just not a part of what they do.
    Last edited by dhergert; Nov-18-2021 at 10:48am.
    -- Don

    "Music: A minor auditory irritation occasionally characterized as pleasant."
    "It is a lot more fun to make music than it is to argue about it."


    2002 Gibson F-9
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    1975 Suzuki taterbug (plus many other noisemakers)
    [About how I tune my mandolins]
    [Our recent arrival]

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