What fretboard radius is most common?

**Dale Ludewig** · Jan-16-2011, 5:55pm

I just finished up a rework on a mandolin originally built by me and went to a 7 1/4" radius (cylindrical). It was requested by the owner. At first I was a bit concerned, especially when I was feeling it without strings on. But after strings were on, it's noticeably rounder than a 12" radius, but compared to a 9 1/2" which was on there before, nothing dramatic. It plays very nicely.

One thing that one must realize is that with a cylindrical board that the outside edges get thinner as you go up the neck. This is just due to the physics involved. In fact I would guess, although I haven't actually drawn it out, that various conical layouts could be had of any starting radius and you could determine the radius at any other spot on the board by maintaining the same thickness on the outside edge. Thus your action is same from the nut all the way to the end of the board.

Oh, and one more thought: I prefer to press my frets in with a caul before the fingerboard is glued on. That would be very hard to do with a conical board. You'd need a different caul for each fret.

**amowry** · Jan-16-2011, 10:09pm

Hey Dale, I press my frets too, and I was surprised to find that I can use a 12" aluminum caul for everything from about 9" up to 16" (which is the range of radii I use for my conical boards) with no problem. I think it's because mando boards are so narrow, and the caul has a very slight amount of give.

**pawnee** · Jan-17-2011, 5:48pm

i agree with williee in the fact that bluegrass can be played on a flat fretboard and sound great, the fretboard is narrow to begin with and do not notice the difference when i play both

**Dale Ludewig** · Jan-17-2011, 5:59pm

Andrew, as I think about it, I suppose I could do the same- use the same caul for a number of different radii. My arbor press plunger, for lack of a better word, pivots in the middle and I already use that fact when I'm on the outside edge of the board. Good idea. I didn't mean to wander far afield from the OP.

**jmagill** · May-15-2011, 7:38am

I'm considering getting a radiused fingerboard, and my luthier has suggested a cylindrical, rather than a conical shape, so these posts have been very useful.

7 1/4" seems to be common for a tight radius, perhaps because gauges for that dimension are easily obtainable(?), but looking at the radii examples at Wikipedia's article here, a 6" radius looks like it would give me the noticeable arched feel I'm looking for.

Has anyone here used a 6" radius with good results?