What did remodelers do before the advent of electric sanders? They used hand-held sandpaper and brute strength. But in 80% of the cases, it is possible to plug in an electric sander and sand with relative ease. Only by buying or renting the right type of sander, though, will you save yourself the effort and time of manual sanding.
Random Orbital Sander
The random orbital sander is the most common type of sander found on store shelves today, and easily the most versatile. The "orbital" part of the name comes from the action of the sanding disk. The "random" part comes from the elliptical motion the disk makes in addition to the orbit. The Black & Decker Mouse is probably the most prominent example of a random orbital sander.
If you had to choose only one type of sander to buy, you should go with the random orbital sander. It is versatile, low-cost, and easy to use.
Pros: Prevents scuffing and scarring the wood if you happen to go against the grain. This type of sander is easier to wield than the belt sander because it is smaller and doesn't make as many wild movements. Changing sandpaper is extremely easy, simply a matter of affixing the paper to the sander's Velcro-like surface.
Cons: If the random orbital sander is your only sander, you may find yourself trying to over-extend its usability. It does not work well for projects where you need to significantly bring down the wood.
Use For: Fine projects, chairs, tables, or trim and baseboards where the surface condition is highly important.
A belt sander has a continuous loop of sandpaper (called a sanding belt) running through the machine, similar to the way the cutting chain runs through a chainsaw.
Pros: Great for ripping off the rougher initial stages of any sanding project. Unlike orbital sanders, which cause the sandpaper to vibrate, a belt sander actually moves the sanding belt. This is a notable difference that you will appreciate when you need to sand down rougher areas.
Cons: Changing the sanding belt and keeping it rotating straight can be difficult with belt sanders. As a result, you may end up with torn belts that needs to be replaced often. Due to space limitations, belt sanders are not good for getting close to walls.
Use For: Removing exterior paint, hitting high spots on wood flooring, removing extraneous wood material, etc.
An orbital sander goes around in tight circles. You will not see the sandpaper head rotate like the wheel of a car. Instead, it makes very small circular motions that are imperceptible to the eye.
Pros: An orbital sander is a handheld machine that allows you to get right into edge spaces. It's safe to use on nearly all materials.
Cons: This sander may not have the impact that you are hoping for. As such, you'll only be using it for fine, detailed work.
Use For: You can use it for sanding wood flooring right near the baseboards, where other sanders will not reach. Or you can use it for smoothing down trim to a mirror-like finish.
Part of the belt sander family, this is a specialized floor sander that must be obtained from rental yards.
Pros: Drum sanders will sand off all sorts of materials that don't belong on your wood floor--paint, adhesive, mastic (just be sure that the mastics and adhesives do not contain asbestos). They will also bring down surface imperfections.
Cons: Drum sanders are very heavy and require two people to transport. If you aren't careful, you can easily gouge into your wood flooring because these machines are so powerful. Like manual belt sanders, drum sanders are difficult to adjust in order to keep the belts running straight. As a result, you may end up ruining drum sander belts, which can be expensive.
Use For: Wood flooring only. Do not attempt to use it for other areas of your house.
Spindle and Disk Sanders
Pros: Table-mounted machines allow for greater stability than with handheld machines. Spindle sanders have the sandpaper on a tube-like base. Disk sanders have the sandpaper on a disk, much like the handheld orbital sander.
Cons: These sanders can be difficult to control.
Use For: Woodworking projects.