Abrasive papers are made of sheets of paper to which a glass grit is glued. Depending on the size of the latter are identified by a number that indicates how many per cm square, so the greater their number the more is said that the paper is "thin". The glazed papers are used in series from the largest to the thinnest by making them slide on the surface to be smoothed by hand or with a pad (piece of foam rubber on which the abrasive paper is fixed).
Rasps and lime
Rasps are special files used to roughen wood, which have much larger and more evident teeth than common lime. These tools, rasps and lime are commonly used to smooth the roughness of the wood. It is advisable to always use them in the direction of the fibers, if possible, holding them in two hands, one holding the tip while the other the handle with long strokes and maintaining a constant pressure. They exist with different sections, square, triangular, semicircular, etc.
The belt sander is an electric tool that turns a strip of abrasive paper closed on two rolls to form a sort of belt. The size of the abrasive belt depends on the power of the motor while the rotation speed is often adjustable.
It looks like a belt sander but thanks to its small size it is more agile and similar to a file.
These are power tools with an abrasive paper tray placed in orbital rotation by an elastic coupling connected to an eccentric attached to the motor.