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What are the most common/your favorite compound radii for fretboards? E.G.- 16" to 20"

Thanks.

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On my steel-string guitars: 12 to 14 with 16” saddle, and 14 to 16 with 18” saddle.
On my classicals 16 to 20”


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steel strings 16-20

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Steve Smith
"Music is what feelings sound like"

^

I like 12" - 16" at 12th, 20" of course at saddle. Steel string.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Think that's a typo - 12 to 16 with 20” saddle? or 14 to 16 with 18" saddle?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Yes, now corrected in post.


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I radius my fingerboards on a CNC router. I tend to like 12" radius boards, so I start with that at the nut. Then in my CAD model of the fingerboard tapered to final width, I draw a straight line down the side of the fingerboard, parallel to the bottom of the board and at the height that the 12" radius at the nut dictates. This will keep the side height of the fingerboard uniform over the length of the board. Finally, I draw whatever radius it takes at the end of the board to hit the edge where I want it and the centerline of the top of the board. I've never bothered to actually measure what the radius is there--probably pretty close to the 16 inches others are using. It's easy enough to extend the model all the way to the saddle to find the matching radius there too.

I probably didn't describe this process very well, but it's quick and easy to do and makes a nice looking and playing compound radius.

Dave

I start out with the 16 at the nut and 20 at the end but then I level the string paths before I fret the board so not sure where the saddle end of the board actually ends up.

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Steve Smith
"Music is what feelings sound like"

I actually hadn't thought about it before, but I think that my CAD based compound radius method probably goes back to what I learned from Charles Fox at Earthworks back in the 70's. There, we radiused our fingerboards with a hand plane, keeping a constant edge thickness and sort of blending it towards the centerline of the fingerboard. Sometime I'll have to measure the radii of the guitar I built up there. I can pretty much guarantee it isn't a consistent radius over the length of the board.

A lot of what I learned up in Vermont seems to have sunk into my subconsciousness, reappearing frequently through the years, but not necessarily recognized as such. I think that's a sign of a very effective teacher.

Dave

Dave

I do something very close to this. I first plane/sand a constant 16" radius into the board, which is already tapered in width before I start the radiusing. Then I use a narrow straight-edged sanding beam to sand each string path flat along its length, blending a bit across the board to make sure there are no noticeable facets. This yields a conical board that is roughly 16" radius at the nut and roughly 20"-ish radius at the end of the board.

I maintain that, as long as the board has some sort of radius that is comfortable to the fretting hand, and each string path is flat along the run of each string, that is all the "compound radiusing" the player needs. It winds up being a de facto compound radiused board, without worrying too much about the specific radii.

That's what I do as well, but now that I think about it I'm not sure it actually produces a conical board since I focus the beam sanding toward the middle of the board to remove the apparent hump in the paths of the outer strings. The nut and end should both still have 16" radius.

I tried modelling it in Blender, and the radius varies in a strange pattern. It starts out at 16" at the nut, then becomes smaller, reaching a minimum around the 4th-5th fret, then gradually increases, hitting 16" again at the board end, and larger as you head toward the bridge and beyond. The string paths are straight while following the board taper, but the shape is not conical. I'm not 100% sure, but I think it's actually superior for string bending. On a cone, pulling a string to the side causes an apparent hump to appear in the path again, but because this one has a sort of concavity to it, you can pull farther before anything bad happens.