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Thread: String width at the bridge

  1. #1
    Registered User sunburst's Avatar
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    Default String width at the bridge

    What string width at the bridge do you folks prefer on an octave mandolin? What width as measured from 1st string to 8th string and what is your preferred string spacing?
    Do you have an OM that you are happy with the string spacing or do you have one that you think would be better wider or narrower?
    I know personal preference is sure to be a factor, but I guess I'm looking for a "standard" that seems to be universally accepted, like there is for mandolins.
    Thanks in advance.

  2. #2
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    Default Re: String width at the bridge

    My old Regal Octofone is the only octave mandolin I've spent any significant time with. The fingerboard is 1 3/8" at the nut, and 1 5/8" at the 12th fret. It is set up with an old one piece compensated mandolin bridge of unknown origin that I modified to work on the instrument, and I string the instrument lightly with unwound strings on the 2nd course.

    The distance between the 1st and 8th strings is 1 5/8" at the bridge, taking the measurement at the center of the string.
    The measurement between the courses is 22/64" between the 1st and 2nd course; and 23/64" between the 2nd and 3rd course and between the 3rd and 4th course, taken at the adjacent edges of the strings.
    The measurement between the individual strings within a course is ~7/64" for the unwound courses and ~6/64" for the wound courses, also measured at the adjacent edges of the strings.

    I don't know if there is any "universally accepted" standard. This works well enough for me on this instrument. I know that on flat top guitars, which vary in fingerboard width and shape, the most common guide for spacing at the bridge is to use the width of the fingerboard at the 12th fret.

    I'm not aware of any "universally accepted" standards for mandolins either, though I suppose there is some consensus on what is "correct" for F-5's and A-5's, since so many of them are built to similar specs.

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  4. #3
    Registered User sunburst's Avatar
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    Default Re: String width at the bridge

    Quote Originally Posted by rcc56 View Post
    ... the most common guide for spacing at the bridge is to use the width of the fingerboard at the 12th fret...
    True, once it's already built. I'm trying to go the other way; start with string spacing and make the board to "fit" under the strings. I've only built one octave mando and that was years ago so I don't remember what the string spacing was. Hoping to get some good info here from players rather than just make a choice based on nothing in particular.
    Thanks for the info!

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    Default Re: String width at the bridge

    Well, if no one else contributes, one of my former students has a Trinity College that he could measure.
    And Walter Carter just listed a Sobell, and has a Gilchrist in stock. Measurements on those would be informative. I will guess that it's quiet enough over there that he would take a couple of minutes to measure them.

    I've threatened to build one several times. If this epidemic lasts much longer, I just might rig up some kind of bending iron and actually follow through with it.

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    Mandolin tragic Graham McDonald's Avatar
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    Default Re: String width at the bridge

    I have always worked on using the same flare (or is that flair?) as a guitar fingerboard. The way I was taught is that the fingerboard width at the 12th fret is the string spacing at the saddle. A 34mm nut width (which is my standard octave mando/ bouzouki width)is a 44mm fretboard width at the 12th and the outside string spacing at the saddle is also 44mm. The saddle spacings can be tweaked a little in or out. Spacings as the diagram below seem to work well.

    Cheers

    Click image for larger version. 

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    Default Re: String width at the bridge

    I built a bouzouki (26") according to Grahams specs. I have been playing the instrument for over a year and am quite comfortable with that spacing. I just finished a pair of octaves (22") and they are currently at 41.2mm. That neck is a bit narrower at 42.9mm at the 12th fret.
    Here is some playing insight for what it is worth. The longer scale length is more suited for accompaniment, and less so for picking melody at least on faster tunes, so the wider spacing allows for that style. THe OM on the other hand would be used for both melody and accompaniment so the closer string spacings may work better. For me the verdict is still out on that since I don't have much time with it.
    Bob Schmidt

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    Registered User zoukboy's Avatar
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    Default Re: String width at the bridge

    My Herb Taylor has 47mm spacing at the bridge (44mm fretboard width at 12th fret, same as Graham's).

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  12. #8
    Registered User sunburst's Avatar
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    Default Re: String width at the bridge

    Graham, perhaps I'm doing something wrong (math and spacial things aren't strong subjects for me), but when I draw the individual string spacing from your bridge drawing my total width comes out to 43mm rather than the 44mm in the drawing. (?)

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    Default Re: String width at the bridge

    Are you making the instrument for yourself or for someone else?
    Personal preferences are so important.

    I play most string instruments to one degree or another. Personally, I prefer wider string spacing for both hands, moderately substantial necks, and although I can live with longer scale lengths, I am not overly fond of them.

    As a teacher and repair person, I have found that what feels good to me does not necessarily work for another person. We're all built differently.

    Will you be building a flat top or a carved instrument?

  14. #10
    Registered User sunburst's Avatar
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    Default Re: String width at the bridge

    Flat top, guitar-shaped OM for a customer. He doesn't have an OM yet, has not developed a preference. I'm just trying to get all the info I can before making a decision. With a guitar-style fixed bridge, once it is done, changing string spacing is not a realistic option.

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    Registered User Mike Buesseler's Avatar
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    Default Re: String width at the bridge

    My Weber Gallatin measures very close to 48mm at the bridge, perfect for me.

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  17. #12
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    Default Re: String width at the bridge

    Hmmm. Perhaps if he can get his hands on a couple of tenor banjos or tenor guitars, he'll be able to give you some idea of what feels good to him.
    Or, if he plays guitar, does he have any preferences there that might serve as a rough guide??
    Last edited by rcc56; Jan-20-2021 at 1:46pm.

  18. #13
    Mandolin tragic Graham McDonald's Avatar
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    Default Re: String width at the bridge

    Quite possibly

    Treat it as a guide.

    Cheers

    Quote Originally Posted by sunburst View Post
    Graham, perhaps I'm doing something wrong (math and spacial things aren't strong subjects for me), but when I draw the individual string spacing from your bridge drawing my total width comes out to 43mm rather than the 44mm in the drawing. (?)

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  20. #14
    Registered User darylcrisp's Avatar
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    Default Re: String width at the bridge

    i would guarantee the folks at Northfield would send measurements on what they build with their flat top octave.
    really nice folks there.
    here's specs from Northfield for just about everything except what you asked for.
    https://www.northfieldinstruments.co...ctave-mandolin
    https://themusicemporium.com/product...ctave-mandolin


    https://www.youtube.com/watch?v=rT8y1wxOcPI

  21. #15
    Registered User sunburst's Avatar
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    Default Re: String width at the bridge

    Quote Originally Posted by darylcrisp View Post
    ...here's specs from Northfield for just about everything except what you asked for...
    Yep, already had those. Thanks.

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    Registered User Marcus CA's Avatar
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    Default Re: String width at the bridge

    I have a Petersen OM with 48mm string spacing at the bridge, but only 39mm at the 12th fret, so I'm guessing that it flares out more than most. (Its scale length is 22.5".) I bought it nearly ten years ago, and it's the only OM that I've ever owned. I wouldn't want the spacing to be any wider, but I can't say that I'd want it any narrower either, because it's what I'm accustomed to be playing. On the rare occasions that I come across an OM, I rarely play them for long because they never sound as good as what i have.
    still trying to turn dreams into memories

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    Default Re: String width at the bridge

    My custom OM is a 20.5" (52cm) scale A-style from Cripple Creek Mandolins (a custom builder listed on the Cafe). String spacing is 46mm at the bridge and the fretboard width at fret 12 is 44mm. The string spacing at the nut is 29mm and the nut is 35mm. I play mostly melodies, flat pick and finger style with a Fred Kelly thumb pick and fingernails, so this spacing suits me well.
    Last edited by luthierseye; Jan-27-2021 at 11:46pm. Reason: spelling

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    Default Re: String width at the bridge

    John- Just got a Northfield flattop octave, 48mm at the bridge, very comfortable. I hope you're doing well!
    Bob Caldwell

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