There are a number of different styles of sanders available, each designed to remove material and smooth wood using sandpaper on a base which have either a circular motion, Orbital Sanders or where the sandpaper rotates, Belt Sanders.
The most common sander is the Orbital sander, which is often referred to as a finishing sanders. They operate with a small circular motion to create a smooth finish when used correctly, they work best when only slight pressure is used.
They are available in three different sizes, 1/4, 1/3 or 1/2 sheet. (sizes in relation to a standard sanding sheet which is 230 x 280mm)
Random orbital sanders combine the benefits of orbital and belt sanders and use Failed to find Class or Failed to find Class , they are also known as Dual Action or D.A. sanders (Replacement Pads are available) They have a sanding pad that oscillate at high speed and also rotates, the random part simply means that the sander can be moved in any direction without causing damage to the surface. These elements ensures that same sanding pattern is not repeated over the sanding area, as such can produce fine finishes, even on contoured surfaces. These sanders are versatile enough to tackle paint and rust removal, and polishing, with the right accessories. It can work along and across the grain making it an ideal finishing sander.
Belt sanders (so named as they use a continuous sanding belt) are versatile machines capable of dealing with the roughest of surfaces have a very aggressive action on wood and are normally used only for the beginning stages of the sanding process, or used to rapidly remove material. They are ideal for stripping wood, floorboards, other preparation work and cleaning up glued panels. Unlike any other sander the belt sander 'cuts' in one direction only which means it can be used parallel to the grain of the work piece minimising any cross grain damage. Variable speed option makes a belt sander more versatile and less likely to damage delicate surfaces, sanding at a lower speed removes less material and creates less heat so finished such as paint and varnish are less likely to meal and fuse with the belt as they are being removed. A wide range of belts are available
Detail Sanders, also known as Mouse , Delta or Corner sanders ,are small and lightweight sanders designed for light use in areas that other sanders are not able to reach. They usually have a small pointed sanding area that is great for getting right into corners or sanding around irregular shapes. Many are supplied with multiple attachments for different applications. Basically they are a small version of an Orbital Sander.
Rotary & Disc Sanders are very similar to angle grinders but operate at much lower speeds, they use circular sandpaper that is rotated at high speed. The rubber pad that the sandpaper is clamped to is designed to flex slightly when pressure is applied. These machines can also be used for polishing and grinding with correct attachments. Scuffing and swirl marks are common when using these styles of sanders which means that another style of sanding is required to give a smooth finish.