I'm preparing to build my first classical guitar (currently researching the instrument's anatomy and the various build processes and techniques). I'm also working through two books on the subject, (the one by Cumpiano, and one by Bogdanovich).
I understand the reasoning behind making the neck angle slightly forward to reduce the bridge height and facilitate setup, and I understand there are many variables that affect the neck angle. But the one thing I haven't seen addressed is compensating for this angle when gluing the neck to the soundboard.
I've seen various building instructions that indicate the top of the heel block is rabbeted for the thickness of the top (simply notched parallel to the top of the neck) using a router or chisel. This would seem fine if the neck and upper bout were in the same plane (180 degrees), but given that the neck is angled forward with respect to the top, should the rabbet not also be angled the same amount?
It seems a non-angled rabbet on an angled joint would result in either (1) a gap in the glue joint, or (2) forcing the soundboard to distort downward (inward) to conform to the angle of the neck. Or am I just misunderstanding this joint? I guess the same question could be asked about the joints for the sides and the heel block, though I have seen that the angle of the side slots are often adjusted from 90 degrees to account for the neck angle.
I hope the point of my question is clear. If this has been covered already, sorry I've missed it. I welcome thoughts and wisdom from all those who have gone through this process before.