I have done more work at the nut slot, enlarging it in the direction of the first fret because anything even close to recommended string height at the first fret makes fretted notes
way sharp. Can you believe the Fender spec for a Strat is 1/64" at the high E first fret, and 2/64" at the low E, with a smooth ramp in between? In decimal, that's .016 (pretty reasonable), then .019, .022, .025, .028, and .031". There is no way "cowboy chords" are going to be in tune with a first fret action that high unless the nut comes another half millimeter or so toward the first fret. I'm going to ignore the spec here, and go with .016" all the way across. Any fretted string is considerably closer to the next fret than that, why should the "zero fret" have to be immensely higher? (
Dave's World of Fun Stuff uses .018" all the way across. And if I'm wrong, nuts are cheap.)
The bottom of the slot was also nowhere near flat, so any nut I would put in that slot would want to rock front to back and be sitting on very little support. My fix for that was to cut a strip off an old credit card that fit in the slot, and then shape the underside of this strip to match the curve underneath it. This I glued down with superglue, and then clamped it by putting the graphite nut (the thicker of the two I have on hand) back in and giving it string tension. The graphite nut wasn't sitting up straight, so I worked quickly and tapped it gently, using the handle of an X-Acto knife with the blade removed to deliver the force. This got it straightened out before the glue set up, and the string tension kept it there.
Once the bone nuts (I ordered two) show up, I'll probably end up using them both: one as the nut itself, and the other to perform
this kind of compensation. However, with the first fret action ridiculously low (it's about the same as the clearance to the second fret when fretted at the first fret, so between .007 and .012" all around) it just about plays all the cowboy chords in tune (
if the tuning is spot on -- it punishes the slightest drift harshly). Since this is low enough that the 6th string buzzes when plucked rather hard (which it will also do when fretted, but not as easily), I am not going to keep the first fret action this low. It feels nice, and it has good intonation, but it's really, really low to the deck.
Fender also specifies action as 4/64" at the 12th fret, all the way across. I originally set it up like that, but the treble side really does not need to be up that high. I'm sticking with the action numbers specified earlier in this thread, measured at the 17th fret. 5/64 at the 17th and 4/64 at the 12th are pretty much equivalent, at least on this instrument.
The locking tuners should arrive in the next couple days, and I hope they help alleviate the tuning drift. Some of it is also due to the cheap stamped metal string tree (I'm only using one), but it will be a while longer before my roller string trees arrive (and I will use both, so I'll have to fill the hole in the headstock and make two new ones). The instrument sounds wonderful when the tuning is dead on, but it's no fun trying to keep it there for more than ten minutes at a time, or when using the whammy bar. Or bending. Or just hitting the strings really hard. It's not the nut (it's graphite at the moment), so it has to be one of the other parts. The high E doesn't need a string tree because I moved its tuning peg to the underside of the headstock, roughly parallel to the A string's tuner. Yet it still goes flat after big bends, so this isn't all due to the craptacular string tree either. (Before you ask, yes the strings are quite thoroughly broken in by now.)
I don't expect the mere addition of a locking element to the tuners to fix anything, but I have some hope that they are of generally higher quality than the ones that came with the kit. The included ones are so twitchy that laying the instrument down on a soft surface like a bed, and the light pressure this induces on the tuner buttons, will cause strings to go flat.
Another place I'm going to completely ignore Fender's spec is on pickup height. They recommend a mere 4/64" between last-fretted string and pickup when using humbuckers, and I tried this. I got weird tuning issues and strings that sounded like they were starting to come unwound. I'll figure out the exact numbers I want to use later, but I lowered the pickups to 6/64" below for now and they seem to no longer interfere with the strings. I had them at 8/64" when I was just guessing at the spec, and that sounded pretty good. This is the recommended height for "Texas Special" pickups (on the bass side, treble recommendation is 6/64), so at least my guess wasn't totally stupid.