Fret Level and Crown

This is the method I developed for doing this job. The marker makes it very accurate, fairly easy and provides excellent results. I won't claim to be the first to come up with this method, but as far as I know I'm the only one doing it.

The first thing to do when starting this job is to remove the strings, or move them out of the way (as I've done here). Next use the truss rod and a straight edge to set the neck as straight as possible, shown here.

Next use a permanent marker to darken the top of all the frets

Now, using a radiused block matching the fretboard radius(longer is better) and 400 grit paper, LIGHTLY sand the frets until the marker is removed from the fret crowns. It is important to use very little downward pressure, and to support the neck near the headstock to prevent causing the neck to deflect when sanding. I should note that I generally ramp the frets down towards the body from about the 17th fret to the heel. Nothing too extream. I find that if you add relief to a neck and use a low action it will typically buzz near the heel because the relief is added between the 18th and about the 5th frets (primarily) leaving both ends of the fretboard high. This treatment prevents/ minimizes the buzzing.

I now know all the frets are level, and I have removed no more fret by sanding than was absolutely necessary. If we were to stop here and polish the frets it would be call a "fret leveling", sometimes a "fret dressing". I avoid this in all but the most minor cases as it leaves wide flat frets which screw with the intonation and can cause minor buzzes.

Now darken the frets with the permanent marker again, and tape between the frets.

Make no mistake, a single layer of masking tape is next to no protection for the fretboard. I take all my files used for fretwork, and sand/polish the edges which will/might come in contact with the fretboard. On my crowning file I did both edges.

This is an inexpensive crowning file which uses replaceable burrs. It works, but I'll soon be upgrading to a diamond file. If you are buying one I'd recommend the basic two sided diamond file in med and wide (one on each side) and 300 grit. It costs more, but if you do this more than once or twice it's well worth it ( so I've been told)

When filing the crowns ensure the fret being worked on is inline with your arm. This helps to keep the file on the fret. Also, do not use alot of pressure. Too much pressure causes slipping which can damage the fretboard, it causes the file to chatter leaving little gouges, and it cuases your arm to fatigue more quickly. Be patient and let the file do the work.

Each fret is filed until all signs of the marker are removed, and finished with a few backstrokes. The back stroke removes some of the major roughness. The marker provides easy visual indication of when enough fret has been removed, and where the filing needs to be concentrated. (I was unable to photograph myself for this step; I use both hands when filing the crowns)

Once all the frets have been crowned, you may choose to redarken the frets and use the radiused block with 600grit paper to check your work by LIGHTLY sanding the tops and checking that the marker is evenly removed from all the frets. I seldom do this as the marker technique is extreamly accurate. Also, you can use a short straight edge(3" or so) to check for levelness as the work is progressing, I find I don't need to do this either.

I then use a flat jewelers file (with polished edge) to knock the corners off of each fret.

Next I use 600 grit paper on a sanding block to finsh the end bevel

I now place this tin shield (one can be made from most any thin piece of tin, or even a pop can) to protect the fretboard when polishing the frets. If the fretboard is rosewood or ebony, I generally don't use it, I simply use the polishing as an opportunity to clean and oil the fretboard as well. (USE IT on a finished maple fretboard!)

The frets are polished first with 600 grit paper (from end to end on each fret) and then with a super fine scotchbright pad. I use my finger tip as the "sanding block" as it will conform to shape of the fret. I also wrap the paper and scotchbright pad around the tip of my finger and go along the edge of the fretboard polishing the edges of all the frets, this tecknique gives a "broken in" feel to the fret ends and fretboard edge. If the fretboard is going to be oiled I will buff the entire fretboard with the scotchbright pad. The fretboard is then wiped clean and a thin coating of boiled linseed oil is applied, allowed to soak in for several minutes, and then the fretboard is wiped dry.

Here's the finished frets, and oiled fretboard. This guitar started with very worn frets. When the frets are very worn, they are effectively wider. Sometimes this causes the crowning file to cut into the sides of the frets slightly when restoring the original crown profile. Switching to a wider profile crowning file will prevent this, but will result in a different than original (or desired)fret profile. I used the original profile in this case.