Files, rasps and rifflers allow you to shape and smooth wood with much
greater control than normal edge cutting tools. Rasps have individually
raised teeth, while files, having straight chiselled edges, cut more slowly
than rasps but give a finer finish. Rifflers are double ended, and either
file or rasp cut.
Although graded for coarseness of cut, files and rasps of a specific
grade will vary considerably depending on their size (larger rasps in
any cut being coarser than smaller rasps of the same cut), and even on
the manufacturer. The size and number of teeth on a rasp can vary from
a very coarse cut (for rough shaping of wood) to extremely fine (for working
curved surfaces in sculpting, carving and furniture detailing).
They are graded "wood" rasps for the coarsest, "cabinet"
rasps (which are in turn sub-divided into bastard, second and smooth cuts)
and "pattern makers" rasps for the finest. Files are graded
coarse for the roughest, followed by bastard, second and smooth cuts.
The sharpness of the tooth depends largely on the surface condition of
the steel and the quality of the polish it is given after it is forged
and milled, but before the teeth are raised.