Originally Posted by theEdwinson
Hey, Joel,
Ever since the beginning, I've put a 15' radius on the backs and a 25' radius on the top. You know, since you asked, I'm not really sure why I've stuck with those numbers, except that I like the way my guitars look and perform with that architecture.
You may be opening up a lively conversation here; I'm looking forward to hearing what other builders have to say about this topic.
I will say that for me, the 25' top radius works very well for the way I build. And when you induce a radius like that onto a load-bearing plate, you are automatically giving it more strength against the torsion of string pull. So you can build that top thinner- actually, more lightly overall- and I think, get more tonal response from it, without sacrificing structural integrity.
Additionally, a radiused top will really help to reduce distortion over time. We've all seen old Martins and Gibsons that have bellied-up behind the bridge, and with a sunken concavity in front of the bridge. This condition often necessitates a neck reset, and/or a JLD Bridge Doctor, or other bridge work, to bring the top back to spec and get the string height back down to a manageable height. Of course, a lot of that also depends on how you brace the top...
I think the reason I settled on the 15' back radius is also a matter of strength, which allows a lighter and more responsive build; and I just like the way it looks.
I think I read somewhere that Kevin Ryan puts an 8' radius on his backs. Anybody know if that's true?
And there is the other factor of avoiding standing waves in the soundbox. Two flat surfaces facing each other might cause the sound waves to just bounce back and forth without really going anywhere- resulting in a woofy, boomy, unfocused projection. But when those surfaces are domed, the sound waves bounce around in there like excited kids on a trampoline.
There's my $ 0.02.
By the way, that is some impeccably clean work you're doing there. Clearly, you're making your jigs and fixtures to have a service life of several generations. If your son Zane decides follow you into this Craft, he'll be pretty well set up!
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