...Remember that first the fingerboard is shaped in such a was as to produce a constant tone all over the top surface of the fingerboard. This means that the side tone will also be consistant all along its edges.
... By tapping the wood of the neck just below the glue line of the fingerboard and comparing this tap tone with the side of the fingerboard we can determine if they are the same of if the neck shape needs to be adjusted to make this acoustical junction match.
...What benefit this might produce is unknown at this time but it seems reasonable that matching tones at this glue line is probably a good thing acoustically. This technique guides us in correctly shaping the neck.
...Tap with the edge of the wood (unsharpened) end of our low-toned tapping pencil just above the glue line on the side of the fingerboard and then immediately just the other side of the glue junction on the neck wood. The fingerboard tone is fixed (once it is adjusted to be even all over) and is not to be changed anymore, so all the changes will be make to the neck shape to make the neck wood side tap tone at the glue joint match the fingerboard side tap tone.
... Go ahead and ensure that the neck thickness is correct and then we will begin to fine tune the neck shape.
... If the neck tone is too high, then material is scraped or sanded off the immediate side shape to lower the tone.
...If however the neck tone is too low, then this tone is raised by rounding off the side curve (or shoulder) area.
...Remove only small amounts of wood and continually check your work progress by tap tone testing as the frequencies change rapidly.
...When the tap tones all along this fingerboard to neck joint match, your job here is done!
