Andy Culpepper wrote: ↑
Sun Nov 05, 2017 10:57 pm
Is it OK to make a perfectly fitting cap over the rod and then glue the fingerboard on top of that?
Any advice would be appreciated.
This is the way I learned to do it on steel string guitars. The one time I didn't use a filler strip the rod rattled at a resonant frequency and had to be repaired, even though I gobbed some silicone caulking in the channel as recommended. Guess I didn't use enough.
I've used the double action truss rods from LMI which have a "step off" at the adjustment end of the rod. Seems like that would give better clearance for the soundboard and that a shorter rod could be made to end where the neck meets body. The other end of the rod doesn't need to extend all the way to the nut and you have some leeway to adjust the fit at the body.
A tapered slot to minimize the chances of "blow out" at the nut end would be easy enough to work out. I've never done that and never had a problem (yet).
The transverse braces can be made a little higher in the middle to acommodate the adjustment hole if needed.