When you run your fingers across the sides of your guitar neck can you feel the frets sticking out? Well you shouldn't be able to. When guitar frets are installed in the fretboard, the fret ends are filed down until they are smooth with the edges of the fretboard. If you can feel the edges of your frets, it doesn't necessarily mean your frets were installed improperly. Humidity plays a big role in the set up and playable of your guitar. When the air is extremely dry, you neck and fretboard will shrink due to the lack of water in the air. The metal frets, however, are not as susceptible to changes in the weather as wood is. The frets will not shrink in dry weather. The result is sharp fret ending poking your hands as you play your guitar. It would take quite some time to go and file each fret level by hand. This is why luthiers invented the fret end file.
A fret file is basically a metal file that is mounted onto a flat block so only one file edge of the file is exposed. The mounting variation allows you to file frets flush without the worry of hitting the fret handle on something. To file the ends of your frets, simply place the fret end file flat against the fret ends. Now slide the file in one direction down the fretboard. Be careful not to bump the guitar body or file off the finish on the guitar neck. Just file nice and slow until you can't feel any fret ends popping out of the edge of the fretboard.
The fret end file is a great tool to have. It is basically a flat version of the fret bevel file. It saves just as much time. It's almost impossible to do a fret job without one of these fret end files. If you don't have one, add it to the list of tools to put in your guitar repair bench. If you would like more information about how to refret your guitar, please see my how to refret a guitar article.