That does make sense and it gets worse. Think about this when we build these things We have to sort of work backwards to get there. First goes the neck angle. we use a straight edge to locate the prolongation of the fretboard just the right distance above the sound board (guitar top) in the location of the bridge, but the bridge isn't there yet. So what is the right height? Well how tall is your bridge going to be and how tall to you want your saddle to be? Don't forget how much do you think the top will deflect (bulge) when you add strings? Some guys build in a solera where thes items are pretty much dialed in as you go but then all things must be equal on all guitars e.g fingerboard thickness, fb taper, bridge height, etc. I build and set my neck angle when the back is attached all off the solera so it's a bit more dynamic and flexible as to the end result.Guitar Slim wrote: It seems what luthiers and techs like Hill and Erlewine are measuring is actually the saddle height, which is more constant, although it does need to be measured against a second point, in this case the (somewhat arbitrary) top of 12th fret. I can see why you don't want to include the height of the nut in this instance. It seems that when luthiers and techs measure a guitar's action, they're usually referring to the the saddle height, not the string height, and perhaps they perfer to do that because it is more constant. While our inclination as players is to just get out the rule and measure the string height. Does that make sense?
Getting back to your point Chris when I set mine up (while building) I have been ignoring the nut and placing a straight edge on a shim on the bare fingerboard at the first fret position at fret height (like a capo) then using a shim at 12th fret location to give me the desired height there then I set my neck angle. THis done and I have a good 12th fret string height and a good saddle height. Then I can go to the nut and dial it in. One more trip to the saddle for final adjustment and its all set up. So there is a time in the process that I ignore the effect of the nut.
This is just me I can't speak for anyone else that builds. Maybe Pepe or SDluthier will weigh in here and give us all a different perspective.