We tend to use the word rasp when we speak about the whole family of rasps, rifflers and files. These are the most overlooked hand tools, but they are the most useful for shaping and smoothing. Rasps can remove wood fast and files will smooth away the shaping marks of the rasps. Consequently, using rasps will remove a large amount of material quickly and will bring the surface to a fairly smooth finish, cutting down the time usually spent sanding.
Most rasps made these days are machine made. Therefore these have teeth in regular rows and these teeth are made by a process called ”stitching” and come in degrees of coarseness from #1 to #15 grain. The #1 to #4 are very coarse and not usually used for wood. They are most often used for stone work. Wood workers are mostly interested in grains from #9 to #15. Most wood rasps used are between 6 and 14 inches long.
Rifflers are rasps or files made for detailing with a narrow profile and come in various shapes. The usual shapes are rectangular, oval, triangular and have pointed heads. These can reach into small spaces. These rifflers are finer with smaller teeth. Some important features of many rasps is one side is flat or slightly convex to help with handling while the other side is often rounded.
Files are for a finer finish and come in many shapes. Files have the same grading system as the rasps.
Use the rasp in a long, smooth forward stroke. It will cut very fast. Then lift it up for another forward stroke. The rasp only cuts on the forward stroke and if you pull the tool back you will eventually dull the rasp.
When you have finished using this tool, use a brush to clean and unclog the teeth. Do not use a metal brush as that will also dull the teeth.
A light coating of oil should be applied to protect the rasp from rust.