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Thread: Ibanez A900 truss rod

  1. #1
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    Default Ibanez A900 truss rod

    I'm working on an Alvarez A900 "Tree of Life" to get it back into playing condition.
    The end of the truss rod has been badly mangled/stripped threads. The metric M4.7 nut on it does not appear to be original and was just turning on the stripped end of the rod.

    I used a "truss rod rescue" boring tool from Stew Mac to expose about a half-inch of new thread in the neck. The tool worked as advertised but I don't know what the original thread specs for the truss rod are. My instinct is that it is NOT M4.7; the replacement nut was probably responsible for stripping the threads. My guess is that it is either a metric M5.8 or a 8-32 thread in US Standard but I would rather get it right the first time rather than risk stripping the newly exposed threads on the rod.

    Anyone out there with a late 70's / early 80's Alvarez mandolin that can tell me the proper size nut for the truss rod?
    Thanks!
    1963 Martin 0-18T, 1967 Gibson ETG-150, 1930s Epiphone Beverly Tenor Guitar, 2013 Blueridge BR-40T tenor guitar, 1960s Goya Tenor Guitar, 1980 Alvarez A900 mandolin, 2020 Kentucky KM-656, Flatiron Mandola, Weber Sage #2 OM

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    Default Re: Ibanez A900 truss rod

    I think you need to change your thread title!

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  4. #3

    Default Re: Ibanez A900 truss rod

    A thread thread!
    If you have a soft dowel that will fit, drill an undersized pilot hole in it, and thread it onto the rod, and remove it. Cut it lengthwise and use an ordinary thread gauge or test screws without cutting it. Alternatively, if you have metric and imperial taps, you can make a test piece out of other materials, like aluminum rod.
    Sometimes, even big companies get erratic with hardware standards and use what is lying around: my MGs have about 5 different thread standards, including a mysterious ‘French metric’ only because, ca. 1920s, they bought WWI surplus tooling from a French Vickers machine gun factory. And unfortunately, used it.

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    Default Re: Ibanez A900 truss rod

    [QUOTE=Richard500;1883804]A thread thread!

    Richard500, great ideas. I especially like the dowel option (less expensive than buying tap & die sets.)
    Thanks!

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    Default Re: Ibanez A900 truss rod

    Quote Originally Posted by Ray(T) View Post
    I think you need to change your thread title!
    I now understand your response. Duoh!
    Any tips on how to edit Ibanez to Alvarez in the title?
    1963 Martin 0-18T, 1967 Gibson ETG-150, 1930s Epiphone Beverly Tenor Guitar, 2013 Blueridge BR-40T tenor guitar, 1960s Goya Tenor Guitar, 1980 Alvarez A900 mandolin, 2020 Kentucky KM-656, Flatiron Mandola, Weber Sage #2 OM

  8. #6
    Ursus Mandolinus Fretbear's Avatar
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    Default Re: Ibanez A900 truss rod

    As a locksmith, I could not live without my "Thread Detective", but there are a number of reasons that even one of these would not help you with this riddle. Good job on salvaging the existing truss rod. While the dowel trick sounds good, the only real solution is to have something in hand with a working female thread. I would look for a package of small assorted miscellaneous nuts to (gently) try. You might even end up with the exact nut that you need.
    Last edited by Fretbear; Nov-09-2022 at 12:01am.
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  9. #7
    Adrian Minarovic
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    Default Re: Ibanez A900 truss rod

    Reading the numbers in the OP.... I would guess either they used standard metric thread which would be M5 on 5mm rod or the US size of 3/16 with appropriate thread (I don't know those US numbers - I guess 10-24 or 10-32?) that most modern US makers use.
    You can measure the old nut, metric M5 would be exactly 8 mm across flats while #10 nut would be 3/8" or 5/16" (which is a hair less than 8mm).
    Adrian

  10. #8
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    Default Re: Ibanez A900 truss rod

    The M4.7 was the right size but apparently the old nut was not properly threaded onto the rod and caused the mangled threads. I used a M4 coupling nut to ensure that I was using all the threads available, it also extends beyond the exposed face of the neck to allow for easy adjustments with a 7mm wrench. The truss rod is working properly now. I'll post some pictures soon.
    1963 Martin 0-18T, 1967 Gibson ETG-150, 1930s Epiphone Beverly Tenor Guitar, 2013 Blueridge BR-40T tenor guitar, 1960s Goya Tenor Guitar, 1980 Alvarez A900 mandolin, 2020 Kentucky KM-656, Flatiron Mandola, Weber Sage #2 OM

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