Setting string height or action on the Classic Guitar.
You must first adjust the bridge by sanding or perhaps shimming
(cyanoacrylic glue works for minute changes) to proper height before being
able to properly adjust the nut (or zero fret.)
Check the BRIDGE for proper height.
With the 1st string, held firmly
against the 1st fret, the distance should be approximately 3/32 in. (no less;
but perhaps 1/8 in. for stronger players.)
Measuring in the same manner, the (bass) 6th string, should
measure 1/8 in. (to 5/32 for advanced players.)
The remaining (2nd, 3rd, 4th, and 5th) strings must be in a straight line
between the 1st and 6th strings.
Check the NUT for proper height.
With the strings in open position, the distance between the
first two strings (E or 1st, and B or 2nd) and the top of the 1st fret should
be 0.025 in.
The remaining strings should be 0.030 in. above the 1st fret.