Inexpensive or imported instruments from a few years ago often have frets that fit loosely in the fret slots. If you tap on loose frets with a solid object you’ll hear a hollow-sounding thunk rather than a crisp, solid retort. So, before leveling the frets on an inexpensive instrument, I flood superglue under the fret crowns and into the fret slots.
Fig. 1 To begin this job, remove the strings and wax off the fingerboard (but not the frets) with standard floor paste wax, and run a bead of water-thin (No. 10) superglue along each fret. The glue will wick under the frets and into the fret slots. This can immensely improve an instrument’s tone by “marrying” the fret to the fret slot. It also ensures that a loose fret won’t lift higher or sink lower than the frets next to it.
Fig. 2 Place the bass face-up on your work surface and prop up the neck near the peghead. Tighten or loosen the trussrod until a straightedge touches all the fret tops. Swipe a felt-tip marker over the top of each fret; as you sand, the color will disappear. When all the color is gone, you’ll know the fret tops are level with one another.
Fig. 3 Use any long, flat object for the sanding block (I use a carpenter’s level). Fasten 320-grit sandpaper to the block with double-stick carpet tape. Support the back of the neck with one hand while sanding with the other. Sand up and down the length of the fingerboard and across its radius, changing the sandpaper several times. Watch the colored fret tops as you progress.
Fig. 4 When the color is gone and the frets are level, feel the beveled fret ends. They might feel sharp, with small burrs protruding slightly beyond the fingerboard edge. Over time the wood shrinks, leaving a bit of metal exposed. You can use an inexpensive ($2) lawnmower blade-sharpening file, available at any hardware store, to remove these sharp edges and clean up the beveled fret ends. Hold the file at the same angle as the fret-end bevels, and file lengthwise until the protruding fret ends are gone. Stop when the file just starts to “kiss” either the finish or the wood.
Fig. 5 After filing the fret-end bevels, there might still be tiny, sharp burrs on each side of the fret ends. In the inset photo, an X-Acto blade is wedged under a sharp burr—these are hard to remove without a specialized tool. In the main photo I am knocking off the burr with Stewart-MacDonald’s Fret End Dressing File. However, if you’re careful, you can do this with your lawnmower blade file.
Fig. 6 Next, to round off the fret crowns, mask off the fingerboard up to the side of each fret, leaving only the frets themselves exposed. Wrap the tape over the edge onto the neck to protect the finish. Here, I’m rounding off the frets with 320-, 400-, and 600-grit sandpaper wrapped around two fingers. I always back the sandpaper with carpet tape so it stays wrapped around my fingers. (You could also use a rubber block instead of your fingers.) Sand the frets lengthwise with long, rapid strokes of even pressure. As your fingers bounce over each fret, the sandpaper will slightly round the fret tops and produce smooth, rounded crowns.
Fig. 7 When the frets and fret ends are sanded smooth, remove the masking tape, being careful not to pull finish from the fingerboard edge. Pulling the tape out and away from the fingerboard can remove finish; instead, pull the tape from the bottom upward and toward the center of the fingerboard. Peeling the tape at an angle while rubbing the tape just in front of the release line decreases the tape’s grip.
Finally, the frets on Patrick’s bass were level and smooth. I’ll continue getting his bass in shape next month. See you then!