I just read MUSIC LOGIC's posts about the necessity for CONICAL leveling along the string path of the fretless fingerboard (and fretted instrument). See it here: Even fretless fingerboard levelling tips
Before, I looked at the diagrams and passed out. When I read the text, it revealed itself as completely simple and obvious. Like, how could ANY luthier or tech not employ this concept 100% of the time when leveling the fingerboard...
BUT DO THEY?
SERIOUSLY, do they?
If not, it might explain the previously unexplainable, taking the voodoo out of guitar setup, and answering the question; "After a perfect fret leveling to compensate for any twists or humps in the neck itself, WHY IN THE NAME OF GOD, does one instrument out of dozens and dozens, sing and play like a dream with ulra- low action, while all the rest nearly
get there, but FAIL, FAIL, FAIL, to be perfect?"
BECAUSE THEY ARE NOT LEVELED CORRECTLY...the lack of
conical radiusing along the string's path on anything
but an instrument where the string spacing at the nut is IDENTICAL to the spacing at the bridge, or with a totally flat
fingerboard (zero radius) will only work perfectly by LUCK, despite the tech's great eye and 10,000 guitar set-up expereince...
Tell me they don't understand conical radiusing and I'll get all my axes to play perfectly!
If this is true, I'd consider it on par with winning the lottery. NO, IT WOULD BE EVEN SWEETER.