Ever wonder about how the picture frame over your fireplace got its decorative sculpted design? Or about the curved edging on your cabinet door or the fluted detail on your bookcase or mantelpiece? Chances are that all were created with the use of a router.

A router is a power tool. A portable one typically consists of two major components the upper housing, which contains the motor and motor-driven spindle, and a base, which receives the housing. The base maintains the motor in vertical position and allows the motor to be raised or lowered.

The electric motor turns a router's chuck at very high speeds. The chuck holds a collet that can be fitted with a variety of bits to cut grooves, trim edges, form recesses, shape moldings and otherwise cut wood. It can also be used to cut plastics of all kinds and soft metals, including aluminum, brass and copper.

The router wasn't always a power tool; the first one was nothing more than a hand plane, a sophisticated chisel of sorts. Legend has it that its wooden version was known as an "old woman's tooth" because of its single projecting blade. The router was an essential tool in the kits of medieval cabinetmakers.

The portable router has become one of the most widely used power tools for the do-it-yourselfer. And with the profusion of styles, models and features available there appears to be no end in sight to its popularity.

Motor horsepower, collet size, handle configuration and plunge feature are factors that determine which router is best for the job or the individual using it. Router motor horsepower ranges from 1/2 hp for light woodworking to more than 2 hp for heavily used professional models. More powerful models generally have higher rpm speeds. The higher the speed, the smoother the cut. All else equal, a router spinning a cutter at 30,000 rpm makes twice as many cuts through a given inch or foot of work as a tool that works at half the speed.

While router sizes are specified by horsepower, it is the size of the collet that determines the maximum shank size of cutters that can be used. Collets come in three sizes: 1/4, 3/8 and 1/2-inch. For light woodworking, 1/4 inch should be adequate. However, a heavy-duty model with a 1/2-inch collet might be something to consider if your work covers a broad range of applications. Many production-type bits and special bits require a 1/2-inch collet.

Handles are important in the comfort and safety of a router. Most full-size routers are designed with two handles, while many small models have a single handle design. Handles generally come in two styles, knob or D-shaped and they can be mounted high or low on the router body. It is best to make an in-store test to decide which best meets your needs.

Routers are available in two types standard and plunge-cutting. In contrast to a standard router, the plunge router moves vertically, usually on posts that are a part of the base. Hence, it can be placed firmly on the work and pressed down to enable the bit to enter the work at a 90-degree angle. This is especially useful when a continuous cut is not desired such as with fluting.

Other factors that might influence your choice of router are switch placement and the ease with which a bit can be installed. In general, the switch is best located where you can operate without moving your hand.

Router bit installation is another matter. Router bits are secured with a chuck, usually a split-collet type, that is attached at the free end of the motor spindle. The collet compresses around the shank of the bit when a threaded locknut is tightened. Sometimes two wrenches are required one to hold the spindle while the other turns the locknut. Some routers are equipped with a spindle lock. This consists of a lever or push button that is used to hold the spindle in a fixed position. This allows the user to use only a single wrench to turn the locknut.

Although a router is typically moved across the material being worked on, there are occasions when the material is moved across the cutting bit. In the latter case, the router is inverted under a stationary table known as a router table. The material is run atop the table as with a table saw. This method works especially well when fabricating large quantities of trim such as baseboard.

The portable router is a delightful tool, but without bits it's like an automobile without wheels. There are numerous bits which will create virtually any edge detail. For occasional use, a high-speed steel bit is OK. For frequent use, a costlier carbide-tipped bit stays sharper longer. Plan to spend two to three times as much for the latter.

As with any power tool, safety is paramount. Always wear eye protection and a dust mask. Due to the high pitched whine created by the high-speed motor and the cutting blade, ear plugs are needed. Keep fingers away from the area of the bit and never attempt to change the bit unless the power cord has been unplugged.