Nut shaping question

[gaucho]

I'm shaping a nut for a guitar (with a flat fret board) that is going to be used mainly for slide playing and very little fretting. Is it best to have the top surface (where the string slots will be cut) flat or is it better to be angled slightly higher at one end. Which end should be higher, the treble side or the bass side. I know the wound strings should sit about 1/2 way down into the slots. What about the unwound strings? I've searched for answers but couldn't find anything specific for slide playing, thanks in advance.

[bryanbradfield]

I’ve fabricated a few nuts.
As you have stated, he amount of string sunk into the nut will vary from about 50% for the 6th string (bass string) to about 100% for the 1st string (treble string).
The 6th string will be about 0.054” in diameter versus about 0.012” for the first string. (really broad averaging).
The distance from the bottom of the string to the top of frets will be quite close, in thousandths of an inch, from strings one through six.
Therefore, measuring from the bottom of the nut slot where the strings bottom out, the amount of nut rising above the string resting point will be about 0.027” for the 6th string versus about 0.012” for the 1st string.
This results in a nut which is slightly higher on the 6th string side.
Nuts which are level across the top, that is to say, the nut is of uniform height, look a bit amateurish to me, as the 1st string has a really deep slot.
The 6th string usually has a bit more space between bottom of string and top of fret. With a flat fretboard, and action that accommodates some fretting with fingers, the tops of the strings will be a bit higher on the 6th string side, but will be relatively flat where the slide rides.

[blueshome]

Go here;
frets.com/FretsPages/Luthier/Technique/Setup/NewNut/newnut1.html