Acoustic Guitar Construction

I'm glad it worked out. My thinking was that taking the top off would have allowed you to make it just right; otoh you saved some work and it appears there are no ill effects. A good learning experience for all of us.

Herman -- did you sand a 28' contour on the shoulder brace too?

Not exactly Ken. I make my shoulderbrace with a flat 1/3 part in the middle and 1/3 part on both sides with about 2mm/ 0.80" taper to the rim. It worked on my former builts. No humps in the fretboard yet.

Herman

Glad this is working out for you -- I do want to comment that .080" seems a like a little too much variance from the center to the ends of the shoulder brace. Our sep-up for the slope (1.5 degrees +/-) from the edge of the sound hole to the neck block only removes less than .060" at the farthest point -- but if what you are doing work well that's great.

I know what you mean Ken. If the fretboardextension with frets in it is quite flat, that 0.060" or so would be the the way to go.
But I have a 0.023" fretsaw and Stewmac fretwire. My expirience is that a ebony fretboard has a significant downbow with the frets in it. And I guess that gives a serious downforce on the shoulderbrace.

This made me think I should give the shoulderbrace a little more curve than the math predicts.
After sanding the arae flat, on my former guitars, this surface comes in line about 3 mm above the bridgearea. And that worked for me. Since I have a bulge behind the bridge in all of them, with a little raise of the bridge, I can work with nice saddleheights.
But on my next I'll try to aim a little less. See what that does for me.

Thanks for your thoughts.

Herman

As a matter of fact in my (and others) designs what your a calling finger-board extenstion "down force" is a very good thing I do not glue the FB extension -- there is no way its going to cause problems with the sound board (distortion). It is some how pushing the neck block out of the way? The neck block tends flatten the FB ext.