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Thread: Pre-truss rod Gibson neck relief?

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    Registered User Andy Morton's Avatar
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    Default Pre-truss rod Gibson neck relief?

    Hi All,
    Did the builders at the terns Gibson factory back at Kalamazoo build any relief into the neck or did these pre-truss rod Gibson mandos have flat fretboards—-and the string tension bowed the neck just enough to provide good relief?

    I am refretting an extensively modified F2 on my bench (now a player with great tone and mojo) that is getting a refret and wondered if anything should be done to the fretboard beyond a judicious FB leveling?

    Thanks!

    Andy

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    Default Re: Pre-truss rod Gibson neck relief?

    A mandolin really doesn't need relief like a guitar. Some put a wisper of relief in the neck, most keep it flat.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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    Registered User sunburst's Avatar
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    Default Re: Pre-truss rod Gibson neck relief?

    Quote Originally Posted by Andy Morton View Post
    Hi All,
    Did the builders at the terns Gibson factory back at Kalamazoo build any relief into the neck or did these pre-truss rod Gibson mandos have flat fretboards—-and the string tension bowed the neck just enough to provide good relief?
    When they were lucky.

    As we know, wood can be unpredictable. You have more control than they did, having seen the amount of neck bow under string tension, something they could not do until after the frets were done. I'd say straighten the fingerboard so that you get the relief you want going by the amount of relief that was already there. Decrease the bow if it needs it.

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    Default Re: Pre-truss rod Gibson neck relief?

    Can we get quantitative about antique tolerances? I’ve been restoring, for fun, antique instruments, mostly trying to maintain original frets, so the baseline is to string up first, measure flatness, remove tension, measure again, and try to wind up flat within a few thousandths everywhere. However, when there’s there’s barely enough material (i.e. old short bar frets), I can run into issues.
    So is there a general rule for a decently playable setup that gives limits for both ‘relief’ and out of plane individual frets? Something measurable?
    Or am I just being unreasonable ?

  5. #5

    Default Re: Pre-truss rod Gibson neck relief?

    The early Gibsons were a short 12 fret to body design, had a maple stiffener insert into the mahogany neck which was wide and very beefy.
    I haven't seen all that many but I think most of them are still as straight as the day they left the factory.

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    Registered User sunburst's Avatar
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    Default Re: Pre-truss rod Gibson neck relief?

    Quote Originally Posted by Richard500 View Post
    ...I’ve been restoring, for fun, antique instruments, mostly trying to maintain original frets...
    Frets are generally considered wear points that are replaceable. For an instrument that is to be played I would not sacrifice proper set up (including neck relief) for the sake of frets.
    As for measurements, there aren't many because action height, string gauge, neck relief and some other aspects are based on personal preference.
    Many mandolin players say they like the neck to be "perfectly flat" with no relief. When questioning them and asking them to check the frets with a string or straight edge I inevitably find that what they are calling "perfectly flat" is what I would call "minimal relief".

    Bar frets present many challenges but also some flexibility in getting proper neck relief. They can be "lifted", which actually usually means removed and replaced higher in the slots, then leveled for correct relief. Also, slightly thicker fret material can be used to "compression fret" a neck to straighten it.

    For mandolins I like to see minimal relief as I already mentioned, for guitars probably .005" to .010" around the 7th fret, for banjos nearly .020". I don't measure, just eyeball the relief while holding a string down at the 1st and 12th fret (except banjos, then the 1st and last fret).

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    Default Re: Pre-truss rod Gibson neck relief?

    add a carbon-fiber stiffener. statistic of one. my no-truss-rod gibson A4 was rebuilt to fix sinking top (now X-braced). original frets were in the wrong places, original fretboard came off (luthier had small problem with the famous nails), carbon-fiber stiffener rod went in, new fretboard went in. result is a much better mandolin, louder and can take medium daddario strings.

  8. #8

    Default Re: Pre-truss rod Gibson neck relief?

    The current subject is a ‘26 Calace, and it now sports a 6mm square carbon fiber beam that extends right into the headstock, because it arrived with a broken neck. The beam goes all the way to the inboard side of the neck block and is epoxy embedded. The original fretboard was obviously delicate, as the frets go nearly through, but I got away with that. Low bar frets were raised by adding solder to their undersides. These are something like 0.037” thick so no easy replacements, but the solder seems to work. I posted the little jig that makes handling the tiny brass bits possible.
    Still wouldn’t dare put heavier strings on this one because it is a bowl back and can still fold up on itself.
    The object mainly is to see if the instrument is, or was as good as the pundits claim: so far it’s pretty good, with strong bass, but once it seasons a bit more, it will get those recommended Dogal light strings to see if it sounds even better. An experiment.

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    Registered User Andy Morton's Avatar
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    Default Re: Pre-truss rod Gibson neck relief?

    Thanks everyone for the help---this helped me to get "unstuck" and progress. I leveled the FB with just a smidgen of relief above the 15th fret. So far so good!

    Andy

  10. #10
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    Default Re: Pre-truss rod Gibson neck relief?

    Quote Originally Posted by Richard500 View Post
    Can we get quantitative about antique tolerances? I’ve been restoring, for fun, antique instruments, mostly trying to maintain original frets, so the baseline is to string up first, measure flatness, remove tension, measure again, and try to wind up flat within a few thousandths everywhere. However, when there’s there’s barely enough material (i.e. old short bar frets), I can run into issues.
    So is there a general rule for a decently playable setup that gives limits for both ‘relief’ and out of plane individual frets? Something measurable?
    Or am I just being unreasonable ?
    Anyone who studies any kind of engineering is taught the difference between "ideal" and "practical."
    If instruments were made of perfect materials, and were not influenced by environmental changes, then those of us who work on them could be mere technicians; and if we were conscientious enough about our work, we would always get perfect results.

    But we are working with wood, and every piece is different. And environment, and environment is not constant.
    Sometimes we just have to make our best guess, and cross our fingers.

    You're smart to take measurements both slack and under tension. That reduces guess work.
    But when we're doing major work on instruments, we're introducing new factors into the equation. Glue a loose spot under a brace, and it will influence the flex of a top. If you pull and replace bar frets, the flexibility of a neck can change. Add a solid reinforcement, and it will change. How much change?? There's no way to know for sure. All we can do is execute the work, string her up, and observe the results. Hopefully, we get it close most of the time.

    Repair work requires both art and science. If we ignore either, the results won't be the best.

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    Default Re: Pre-truss rod Gibson neck relief?

    Quote Originally Posted by Jim Hilburn View Post
    The early Gibsons were a short 12 fret to body design, had a maple stiffener insert into the mahogany neck which was wide and very beefy.
    I haven't seen all that many but I think most of them are still as straight as the day they left the factory.
    I've worked on quite a few of them. While I wouldn't necessarily say that they are "still as straight . . .", in most cases they are remarkably resilient, and don't need any more than very modest correction. I think it's fair to say that most of them hold up very well as long as they haven't been neglected, overheated, or over-strung.

    And their mahogany and ebony tended to be hard as a rock. I wish it was still easy to get wood like that.

    I will mention that very early examples do not have the triangular maple stiffener. I don't know exactly when the reinforcement became standard, but it was sometime in the early 1910's.

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