A grinder uses grinding wheels or grinding stones for many jobs, including cutting metal, polishing, and removing paint or rust. Grinders are overall more versatile and powerful than sanders and are made for rougher surfaces, with up to 11,000 rpm. You can mount larger discs and finish jobs faster. Sanders are used mainly in woodworking and smooth surfaces using a disc. Grinders can be used as sanders, but a sander will have a smoother finish. If you commonly work with soft wood that needs a smooth finish, it is worth it to get a sander in addition to a grinder.
You can choose between a pneumatic (air) grinder or sander or an electric one. There are advantages and disadvantages to each type.
Advantages of electric:
Advantages of air:
Make sure you know what environment you are working in before you choose your grinder or sander, and carefully consider the advantages and disadvantages of each type.
Disc sanders include orbital, random orbital, angle, and vertical sanders. These are all characterized by having a disc perform the smoothing. They differ in disc size and in the shape of the sander itself.
Orbital and random orbital sander:
Besides a disc sander, the other most common type is a belt sander. Instead of a disc, belt sanders use a sanding belt and can be either handheld or stationary. There are other types of sanders as well such as sheet sanders and palm sanders.