Diamond Fret Crowning File. • An excellent finish results and a fully polished fret is quickly obtained by going through the sandpaper from coarse to fine grit: 800, 1000, 1200, 1500, 2000 and finally 2500 grit - it's only a couple of rubs with each and when you use the spring steel strip to protect the fretboard then the paper glides across the surface of the fret and strip easily.
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