If you notice the strings on your guitar are buzzing when they are played open (plucked without any fingers on the fretboard), you may want to consider replacing the nut at the guitar peghead. A nut may need to be replaced due to wear and tear, or if a fret repair job has caused the tops of the frets to be too close to the string action of the grooves from the old nut.
Prepare to remove the existing nut. Take a small block of hardwood, approximately 1/2-inch by 3/4-inch by 3/4-inch and place it snugly against the nut with the block resting on the fret board.
Take your plastic-headed hammer and give the wood block a small but firm tap. Repeat slightly harder if the nut does not separate from the fret board.
Remove the nut and clean the nut groove with your chisel. Be especially careful as you clean the ends of the groove. The groove needs to be smooth and flat and in full contact with the nut for the best sound.
Take the bone nut material and hold it against the nut groove. Mark the exact link and cut to length with a small dovetail saw. Begin by cutting slightly long and then sand to the exact length that you need.
Fit the nut to the groove width. Hold the nut against the fretboard and mark the width of the groove on the nut carefully.
If you need to reduce the thickness of the nut, do so with 120 sandpaper that you glue to plywood to form a sanding stick. Hold the nut with your thumb and first two fingers and sand on the block lightly and evenly. Do this carefully and check it against the nut groove until it is exactly even.
Once the nut sits snugly in the nut groove, take a sharp pencil and trace the fretboard height directly onto the nut.
Remove the nut and cut to within 3/22 of an inch above the fretboard. Do this with your sanding stick or your file.
Angle the nut to match the slope of the peghead. This also can be done with sanding sticks or your file.
Lay out the first and sixth strings on top of the nut with a sharp pencil and straight edge. Usually these strings are inset about 1/8 of an inch from the nut ends.
Take the dividers and set so you get five even divisions between the two outside lines. Mark each of the strings with the divider and strike one light line at the location of each string.
Take a 6 to 8 inch straight edge and place one end at the backside of the mark at the low "E" string where it meets the fretboard. The other end should be placed against the peg in the peghead for this string. Strike a sharp pencil line on this string. Complete this same step for all remaining strings.
Take the gauged fret saws or files, and file a shallow groove at each pencil line. Make sure each groove is centered on the lines. Start the groove by guiding the saw with the thumb of your opposite hand.
You can estimate the groove depth for the strings; however, if you cut too deep you will have to start over.
Glue the nut in with a couple of drops of nut adhesive and let dry. String up your instrument with new strings and you are ready to play.