The fret edges on a guitar neck can become rough and worn through constant use as a result of impact damage or as a consequence of the guitar losing moisture and the wood shrinking. By investing in the right tools and learning some simple techniques, you can carry out your own repairs to redress the frets and keep them in good condition. Taking the time to undertake this essential maintenance will preserve intonation in your guitar and protect strings from unnecessary wear and tear.
Remove the strings from the guitar and rest it face up on a solid work surface. Use an old towel or cushion to provide support for the neck as you work.
Scrape any accumulated dirt and grime from the fingerboard between the frets using the straight edge of a razor blade. Clear away the debris and sand the fingerboard using 320 grit sandpaper. This is usually adequate, but you can progress up to 1,000 grit wet and dry paper if you wish. Buff the wood to a shine.
Mask the space between the frets with decorators tape. Where the tape meets the edge of the frets, try to make sure there is only a single layer of tape; otherwise, this will hamper access for the finishing tools and create discrepancies in the levels across all frets. This can cause problems with intonation and setting the action of the strings. Use some tape to protect the edge of headstock and the face of the body where the neck joins.
Rest the straight edge of the spirit level across the frets to determine how straight the neck is up to the point where the neck joins the body. If the neck is bowed in either direction, use the appropriate tool to adjust the truss rod until the neck is straight.
File the fret along the length of the neck with the fret leveler or mill file, using long, gentle strokes. Avoid pressing too hard as this may cause the neck to bow as you work, which will introduce discrepancies in the final finish. The fret tops will flatten as you work since they will all be brought to the same level. You should file the portion of the fret board that extends beyond the joint with the guitar to drop off from the main level of the neck, but, again, they should be level with each other. Clear away all the debris when you are finished.
Re-crown the flat-topped frets using the crowning file. This process brings back the rounded finish while preserving the leveling. Place the concave side of the crowning file over each fret and file until you see only a thin line remaining on the top of the fret.
Dress the ends of each fret to smooth off any final rough edges. Use a special fret dressing needle file, which has its edges ground smooth to prevent damage to the fingerboard. Work the file around all surfaces of the edge to make sure no rough edges remain. Repeat this process for all frets. Check each fret by hand to make sure you haven't missed any rough spots.
Add further lengths of masking tape along the length of the neck running beside the edge of the fingerboard. Use the 220 grit sandpaper held in your fingers to rub gently across all the frets to eliminate the scratches left by the filing process. Work you way up to 1,000 grit paper to bring a high, smooth shine to the frets.
Remove all the masking tape carefully to avoid stripping off any of the finish on the neck. Carry out one final check for any rough edges you may have overlooked and give them a quick file if required. Finally, apply a coating of neck oil with a rag, and your guitar will be as good as new.
Tips & Warnings
- If the sharp edges have been caused by the neck drying out and shrinking, it may be worthwhile to invest in a small humidifier for your guitar.
- If you're working on an electric guitar, you should tape a piece of cardboard over the pick ups to prevent the metal filings sticking to them since they can be problematic to remove.
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