Hi Rebecca. I use one frequently to put a "coin edge" on bracelets.
You have to really control the file so you're moving in a straight
line along the length of the file. I'll make one pass, then move the
file over about half the width of the file and make another pass,
etc. With each pass, make sure the file is seated in the grooves from
the previous pass, to give an uninterupted pattern.
True checkering, though, comes from making a second series of passes
over the same piece, but from a different angle. This creates a
pattern of diamonds, such as is frequently found on gunstocks and