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Thread: Is there an ideal Radius Setting for mandolins?

  1. #1
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    Default Is there an ideal Radius Setting for mandolins?

    Just trying to get some people that might help me get this answered. I am trying to find out if there is a widely accepted radius measurement on a mandolin fret board that seems to work best for most people. I know a lot of mandolins on the market have flat fret boards but I know for me that is out of the picture. What would all of you say seems to work best for you? Radius of 7.5, 8, 9.5, 10 12 14 ? Thanks for any info.

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    Registered User Drew Streip's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    I wouldn't say there's one widely accepted standard but I just did some research from "modern" makers and found this interesting:

    Northfield talks about their A5 Special: "Fingerboard Material / Radius: Ebony / 5.7" (145mm) at nut, 7.7" (196mm) at 20th fret"

    Collings also says: "a compound 5 1/2 to 11 5/8 fingerboard radius"

    Both of those seem a little extreme to me, but then again I haven't played either one. I put a straight 12" radius on my backup mandolin (formerly flat) and it felt very natural, since i come from a guitar background.

  3. #3

    Default Re: Is there an ideal Radius Setting for mandolins?

    I put an 8.5 on mine when I ordered it and haven’t looked back. Plays like a dream, but that’s a little extreme for many players. I played a Weber Fern with an 8.5 years ago and knew that if I ever built a mandolin I would have to have that radius.

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    two t's and one hyphen fatt-dad's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    more at the nut, less at the bridge.

    f-d
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  6. #5
    Confused... or?
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Maybe it's better to think of radius like gloves: some fit your hand better than others, and probably different from my hand. Using "the communal experience" to determine your fretboard radius can't be as useful as accumulating your own experience. Besides, your preference for feel, sound, even style of music, will probably change over the next 5, 10, 20 years (which is why they invented Mandolin Acquisition Syndrome).

    Personally, I like the feel of radiused boards better than flat (no clue what radii they might have been), but have not been strongly enough moved to actually own one; sound & overall feel =width, thickness, back contour, angles= are more dominant than, and all interact with, any given radius. (A radius does provide more finger-room between strings, thus making the board seem a bit wider).

    Besides, being adaptable, at least in the short term, is probably a more useful trait than finding a preference and converting that into a requirement.
    - Ed

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    Lurkist dhergert's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    FWIW, when a number of us here on the Cafe got the inexpensive MKlfstb (Dragonfly) F-style mandolins on a blow-out sale a few years ago, their specs spoke of them as having a (non-compound) 12" radiused fingerboard...

    I have never been able to feel a radius related difference between my MK and my F-9 which has a flat fingerboard, and the two mandolins are otherwise setup as similarly as possible (my MK serves as my backup mandolin).

    Wondering, after reading this thread, I've just checked the fingerboard on my MK with a straight-edge: it's flat as a pancake. No radius. So that probably explains why I have never felt any difference. I have to say that I was suspicious anyway because the four MKs that I ordered all came with a flat (non-radiused) bridge.

    Aside from the MK veering from the advertised specs (for $199 I have no serious complaints), I personally really have no problem with flat fingerboards; all of my other fretted instruments (banjos, guitars) have flat fingerboards and I'm used to them.

    But it makes me wonder how many other mandolins advertised with a 12" radiused fingerboard are really flat. It strikes me that a true 12" radiused fingerboard on a narrow neck instrument like mandolin might be nearly imperceptible, especially to those of us who are not used to them from other fretted instruments.

    Is there any shared wisdom from those of you who are used to a true 12" radius? Can you really feel a difference on a narrow mandolin neck?

    Edit: ... And, this thread raises another question for me: If you have a fingerboard with a compound radius, which radius is the bridge using?
    Last edited by dhergert; Sep-26-2019 at 11:42am.
    -- Don

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    Registered User DavidKOS's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    I honestly do not know the radius, but when I commissioned my Italian flatback from Ernie Fischbach, I had played his other instruments with a flat fingerboard, and wanted a slight radius.

    The flat fingerboards often feel as if they were concave!

    I know they are level and flat- therefore to compensate, I knew I needed a very slightly radiused fingerboard on my 27 fret neck.

    It works really well!

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    Registered User sunburst's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    There is no "ideal"... it is personal preference (as with many things).
    Mandolin fingerboard are narrow compared to guitar fingerboards, so the same radius used on a mandolin as on a guitar is less noticeable. A 16" (Martin guitar) radius is hardly noticeable on a mandolin fingerboard. A 12" or 10" (Gibson guitar) becomes detectable for most people on a mandolin 'board. A 7.25" radius (Fender guitar) seems just about right to me and that is the radius I use for mandolin 'boards. Some people don't even notice that radius on a mandolin 'board.

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    Purveyor of Sunshine sgarrity's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Yeah.....flat!

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    Default Re: Is there an ideal Radius Setting for mandolins?

    So far, none of my customers have asked for a flat fretboard. I've done compound radiused fretboards entirely, flattest was 10" at the nut and 14" at the bridge, the most extreme was a 4" radius at the nut. My standard is 8" at the nut, 10" at the bridge.

    BTW, the difference between a 4" radius and an 8" radius, and between an 8" radius and flat, is 1/2mm (.020"). It's not a lot, I doubt most people would really notice a 4" radius vs an 8"-10" radius if they were already OK with a radius.

    There is no detectable difference between different radii after 10". 10, 12, 14, you're talking about a variation of .1mm/.005", which is the thickness of a couple sheets of paper.

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    From my experimentation, I think the main ergonomic consideration is actaully the shape of the neck, not the width or radius of the nut. People who want a super narrow neck, like 1" or 1 1/16", probably would be just as happy with a shallower, more slender neck and a more normal nut width.

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    Registered User Eric Hanson's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Marty,
    Thank you very much for this information and perspective. It is really nice to have clear information, and real world experience paired together.
    Eric Hanson
    Click #016/ Born on 2/29/08 - Sold to the next Conservator of this great mandolin!
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    Phil Goodson Philphool's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    In theory, the way to make an ideal compound radius is to note the difference between the splay of the strings on the nut and compare to the splay on the saddle.
    You then construct a CONE that has those measurements on its surface and make the FB radius match the cone at every point from nut to saddle. This allows the strings to remain at the same height from string to string as you go up the fingerboard instead of being higher on the G & E strings high on the FB.
    How near the cone point you start to duplicate the surface determines the actual numbers.

    I've probably left out a few geometric details and the mathematicians among you should feel free to correct me.

    But in real life, it doesn't seem to have to be so exact.
    I have had at least one mandolin where changing to a compound radius made a noticeable improvement for me.

    I certainly agree with Marty that the neck shape probably means a lot more.
    Phil

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    Default Re: Is there an ideal Radius Setting for mandolins?

    To visualize Phil's point, it is not feasible for it to be a cone... the geometry gets really awkward. Instead we draw it so the it's like a cone, but with one edge of the circles aligned instead of their centers.
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    Registered User sunburst's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Quote Originally Posted by Philphool View Post
    ...in real life, it doesn't seem to have to be so exact...
    In light of that I often wonder if some of them are any closer to ideal than a simple straight radius. I especially think so considering how much easier it is to level frets without a "compound" radius. My guess is that "compound" radii are generally not closer to ideal than simple radii.

    Some people say it is easier to pick the strings when there little or no radius at the bridge and us that as a reason for using a "compound" radius. Considering that guitar players have been picking strings with a radius at the bridge successfully for many years I consider that reasoning to be suspect also.

    (Any extra points for using the proper plural of radius? )

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    Registered User Gunnar's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Well, FWIW, on my guitar when I'm playing the sligo maid, (learned from Paddy Cummins' free sample lesson from the OAIM) I almost always miss the E string because it's lower than the B string. So yes, the radius does make a difference on guitar too.
    Mandolin: Kentucky KM150
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  25. #16

    Default Re: Is there an ideal Radius Setting for mandolins?

    A compound radius makes a bigger difference on electric guitars where you are bending the strings much more.
    Spruce dork

  26. #17
    Adrian Minarovic
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Quote Originally Posted by grandcanyonminstrel View Post
    A compound radius makes a bigger difference on electric guitars where you are bending the strings much more.
    I had a customer few months ago with his electric guitar with problem with bent strings, when he bent string (he commonly does 2 semitones and in few cases even 3 semitone bends) the string got muted or slight buzz by next fret when he displaced the string too far beyond the apex of fret curve. We had to find optimal setup of bridge and neck relief for good playability and clean bends (we succeeded and resulting setup was even tiny bit lower than before on majority of board)
    No such problems with flat boards...
    Recently I do mostly flat boards, but in the past I preferred compound "radius" that approaches almost flat bridge. I don't use word radius as actually except the two spots (at most) there is no circle anywhere in the crossections. Of course the difference from circle is rather small, but it is there.
    Adrian

  27. #18
    Registered User Tom Haywood's Avatar
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    Default Re: Is there an ideal Radius Setting for mandolins?

    Perhaps the main lesson I've learned in lutherie (and life) is that everything depends on achieving a balance. "Ideal" is the perfect balance between differing forces, differing goals. That balance is never static, and is always different depending on the different goals and changing forces. Even if part of it is relatively static, such as the radius carved into a piece of wood for the fret board, lots of things (such as the weather and how you play the instrument) will change the balance as indicated in some of the posts above. For that reason, I can't imagine finding a generally ideal radius. I used to put a 10" radius on my mandolin fret boards because that is mid way between 7.5" and 12", which were popular numbers when I started building. I now use a radius which can't be calculated - it is either 0" or infinity inches depending on how you view the math. That is the ideal radius for me - currently.
    Tom
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