I've done two builds(00-12 fret), both times using a 28' radius on the top, and 15' on the back. This created a radius that was conducive (mostly) to the proper neck angle/bridge height combinations. It also creates quite a dome on the whole of the top.
I've read that the tighter the dome, the less "sound/tone" (for lack of a better word) you'll get out of the guitar. This makes sense, being that a sherical dome is one of the stronger shapes to be had. Of course, the top of a guitar lies somewhere between a flat place, and a tightly domed sphere.
I've also read/surmised that with a 28' radius top, you'll have trouble replicating that vintage sound.
So, how did Martin build their tops and backs in years past?
-arch braces to 40' radius, then glue onto a flat top?
-use 40' braces glued onto a 40' top in a dish?
-use a 40' radius and glue it onto UNRADIUSED sides?
-Use a 40' radius, glue onto flat sides, but sand a 1.5degree slope into the rim from the Upper Transverse Brace to the neck block?
How about the back? 15' radius? seems tight, but it's the back, so it might be good to have this tightly domed...
I'll be building a 12 fret dread (hopefully many) and I don't really want to use the 28' dome, wouldn't be prudent. I'm thinking that a 40' radius, flat rim, and 1.5 degree slope from the UTB up.
As usual, many thanks for any info you all may have. Much appreciated.