Hi Derek, the radius on a wider fingerboard is to facilitate easier playing of chords and fingering. On the narrow fingerboards used on 3-4 strings I don't feel the need, for me.
I use fingering and slide styles so the strings are set up flat (do not follow the radius of the f/b) so a radiused fingerboard does not work, I also use a capo so the outside strings are put out of tune by being higher than the middle strings off the frets.
But it's a matter of taste. Make sure your frets are a good tight fit in the slot with a radiused fingerboard.
That's a great point. Never having made one (yet) I didn't think about that. Most frets are probably straight and don't have a natural arc to match the radius. That makes sense. Thanks.
I never put a radius on the ones I built. I must say my first guitar was an acoustic with a flat fingerboard. It's the type of thing you get used to.
If it's going to be fretted, you'll at least want a round over of the edge for better comfort.
I've only built 3 string CBGs so far myself, but the next one is to be a 4 string with a 23" scale tuned G2, D3, A3, E4, (Irish Tenor tuning) and I plan to use a flat fretboard.
I play an Ibanez AVT1 Tenor Guitar (23" scale) that has a 1-1/4" neck width at the nut, and 1-1/2" width at the 14th fret, where it meets the body. The published radius per Ibanez is 400mm, or 15-3/4". The height of the (mathematical) chord segment at the center of the fretboard in relation to the edges is an itty, bitty 0.218mm, or 0.0085" at the nut, and 0.383mm, or 0.0151" at the 14th fret, which to me is just about flat. It feels flat to me when I play it, no different than my flat fretted 3 string CBGs. It seems to me like it would be a lot of frustrating work with little to gain from it.
Good luck with your build!
I had to read your post a couple time but I think I get it. I was wondering the same thing, especially on a narrow neck. I was originally going to do a 4 string build but I think I am going to do a 3 string build. Not so much because it is easier to build, but because I think it will be easier to play and learn.
My goal is to make radius fretboards on all my CBGs. Not having a good go at it at the moment. A radius between 12 and 14 matches the curve of your fingers. So it would make chording easier. Even on a 1.5 inch neck.
This is really good advice! Well said Bruce.
A good plan. It’s one of those things where we don’t know what we don’t know until we venture forth. Though I wasn’t a guitar player when I started, and my son was (10 years playing), I had extensive woodworking experience. But in half a dozen builds, I’ve learned a lot about stuff I had no clue were even important. How to manipulate action height and scale length and so on to achieve intonation. How to diagnose and fix buzzing, the makings of good nuts and bridges, pickup selection, placement, etc. you’ll learn about tone woods and designing for acoustics and for strength. It’s a lot more than woodworking, but solid woodworking skills are a huge plus.