Acoustic Guitar Construction

I finally ran across the vid where Robbie briefly mentions his reasons for the 3" distance from rim to peak on lower bout braces.

https://youtu.be/7ClFeZ769BE?t=2m23s

Nice vid. But "reasons" for making the distance exactly 3"? I don't see that here. I do it this way also, but only because the plans tell me to do so. I did not made them an other distance. So I can't tell this is the best way to do so. Maybe others can.
Herman

I agree that 'exactly' is not needed. But I have seen a number of pix where the peak was only 1" or so from the rim - and I'm pretty sure that that is not optimal.

And there's Roger Siminoff -- he has written that the peaks do absolutely nothing.

So in Robbie's course he is building an OM, how would a larger or smaller format guitar effect this measurement? It seems as though a smaller or larger body with shorter or longer braces would effect where the node would be and therefore the peak placement on the brace. Any thoughts?
Jim

I have a few prints/drawings that were made during reconstruction projects

The node measurements are:

"D" Herringbone 3"

000 12th fret 3.625"

J200 3.5"

J185 2"

Good info.
Somewhere on the UMGF, John Arnold listed all the measurements he took of a 1935 D-18, what he considered to be a very great sounding guitar. I will try to find those this evening and post it if I can find it.