Fret end dressing files are used to file the burrs off new frets that are added to a guitar.
This turns the fret convex, eliminating any sharp corners or burrs and making it safe and comfortable to play the instrument.
The safe edges prevent damage to the fretboard, although you will still need to be careful to make sure you don’t scratch the fingerboard with the tip of the file.
These files can also be used to clean dirt from files as an alternative to wire wool. Using the file is less likely to result in damage to the guitar’s fretboard.
What are the characteristics of a fret end dressing file?
Cross section
Fret end dressing file are shaped a little like square files, but with a concave opening cut into one of the file’s faces.
Profile and cut
They are blunt, and cut on the inside of the concave section, but safe everywhere else.
Size
Fret end dressing files come in three sizes: skinny, medium and large, which can either be found as separate files or as attachments for a dedicated handle. They do not follow Swiss or American pattern guidelines.
The size of file that you need to use depends on the size of the frets on your guitar. It’s a good idea to take your instrument with you if possible when buying your file so that you can check to make sure you choose the right one.