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Is there a compromise?

Posted: Wed Jun 07, 2017 7:30 pm
by Mike Bradley
This is a topic that has come up time and time again, but doesn't seem to be very clear. When radiussing a fretboard( 16" in my case), it is not possible to achieve equal thickness at the edges of the fretboard all along it's length AND along it's centre line. If equal edge thickness is achieved, then the centre thickness will be slightly thinner at the nut end than the soundhole end. If the centre line is equal thickness along it's length, then the edge thickness will be thicker at the nut end. So is there a compromise?
I notice that many factory built guitars appear to have equal edges, so I can only assume that the centre lines are thinner at the nut end. Is that the way to go?( of course , ultimately this will have some impact, however small, on the neck geometry/angle.)
Thoughts?

Re: Is there a compromise?

Posted: Thu Jun 08, 2017 12:31 am
by John Parchem
I never cared myself But you can use a compound radius. The compound radius tries keep the fret board level under each string as the width increase the radius increases, I believe as side effect the edge of the fretboard can keep the same thickness.

Re: Is there a compromise?

Posted: Thu Jun 08, 2017 8:36 am
by Mike Bradley
John Parchem wrote:I never cared myself But you can use a compound radius. The compound radius tries keep the fret board level under each string as the width increase the radius increases, I believe as side effect the edge of the fretboard can keep the same thickness.
Thanks John, it's not that I care so much but just wondering what's acceptable. This is my first guitar build and first attempt at radiussing a fretboard. I'm sticking to my plans of using a 16" radius, and will take what comes as I don't want to complicate things at this stage by trying a compound radius. Cheers Mike.

Re: Is there a compromise?

Posted: Thu Jun 08, 2017 5:07 pm
by ken cierp
Martin factory made finger boards "are not" a uniform thickness end to end. While the nut end is .25" +/- the extension end is slightly thicker (.010) so that when the edge tappers are cut, the reveals are about the same end to end and the markers are visually centered. My Martin Engineering contact gave me this bit of trivia.

Re: Is there a compromise?

Posted: Thu Jun 08, 2017 5:22 pm
by Mike Bradley
Thanks Ken, I was thinking along those lines. Makes perfect sense. Cheers Mike

Re: Is there a compromise?

Posted: Fri Jun 09, 2017 7:28 am
by Herman
Mike,
I use a compound radius 12-16" on electrics. As said with a staight height, the fretboard is a bit higher in the middle up the neck. And when you bend strings on the E and B string, they can buzz against the frets on the middle of the fretboard. A compound radius grants a tid lower setup there.
But on acoustics on the other hand, where bending is lesser performed, in my view a "one radius" fretboard is not a big issue.
Hemman