: a file having teeth of a grade next finer than coarse.

What is bastard file used for?

These Mill Files are commonly used for millwrights' work and are ideal for sharpening circular saws, hand saws, chainsaw teeth, knives and can be used for, finishing, and general shop use. These files are most effective when filing with the drawfiling technique or lathe filing technique.

What is a double cut file used for?

Double-cut files feature a second set of teeth that cut in the opposite direction and are used for more aggressive filing, shaping or removing rust from metal and smoothing wood. Use heavier pressure when working.