Official Luthiers Forum!

I have been reading up on the past discussions of neck angle and top plate angle vs. the neck block.
I understand that on my neck I will be using an 88.5 degree cross-cut to achieve the correct neck angle as compared to the neck block.
For the top I have found that many builders radius the top, then flatten/sand the rim on the upper bout. Also, no radius is added to the braces in the upper bout before gluing down on a flat surface.
When sanding the rim, to remove the radius and make flat, in the upper bout, should the rim be sanded 90 degrees to the neck block or to 91.5 degrees to be parrallel with the neck/fretboard?
My guess is that the 'fall away' at the 14th fret is due to sanding to 90 degrees and that the 'hump' could be caused by not sanding to 91.5 degrees or less.
Could someone confirm that I have this fit figured out or let me know if I have missed something here?
thanks.

_________________
Chris Oliver
Infinity Luthiers
...in the shop.

live every minute...

Ok! Here is what do. I dome sand the entire rim and neck block. So now the neck block has the dome radius sanded into it. I brace everything with the radius. I use a 25' top radius and attach the top as a continuous dome.

Food for your thought process:
If you drew on paper a line tangent to the 25' radius at the mid point of the typical 25.4" fretboard extension you would find that line is very very near 1.5degrees (88.5 depending on plane measured from). So the dome its self forms the basis of the 1.5 deg. plane

With that said; I then sand the area of the fretboard extension (only) till I for a flat plane from neck joint to end of the fretboard extension in the area of the FB extension This plane I just sanded into the top is an extension of the neck angel and required very very little sanding to achieve a flat plane. In fact all I am really doing knocking the high area of the top at the FB extension down till the sides of the extension set flush against the top. I am not changing the angle of that tangent plane at all just flattening it.