How I Intonated My Guitar Saddle

First I made the nut.

The finished nut.

Next I inserted a wire (a short length of .046 guitar string) under the strings and along the center of the saddle.

After tuning the strings, I checked the 12 fret harmonic and moved the wire backward or forward under each string until the 12th fret harmonic matched the open string. For accuracy, I used a digital tuner. Then I marked the position of the break point with a pencil.

I used nut files to slot the saddle while preserving the position of each string's break point. To achieve good action, I removed the saddle and sanded off material from the bottom of the bone. Doing this allows the saddle to sit lower in the slot and bring the strings closer to the frets. Of course, I had to test fit several times to get the action right. Finally, I rechecked the intonation and used my nut files to fine tune each string's break point.