The portable electric router is probably one of the most versatile of all woodworking power tools. But it is also one that few home carpenters and workshop enthusiasts own. Many are not even familiar with this tool.

A router can be used to cut dados, rabbets and grooves of all kinds, as well as to make fancy moldings, or cut molded, beveled, curved, carved or rounded edges on existing lumber. It will also speed up and simplify the task of making almost any type of woodworking joint, including mortise-and-tenon, tongue-and-groove, splined, rabbetted and the aristocrat of all joints, the dovetail joint, widely used in assembling top-quality drawers.

In addition, the router is the only portable power tool that can be used for trimming off edges of excess material when applying plastic laminates to surfaces or edges, and for such jobs as carving recesses for decorative inlays. It is also used in carving numbers, letters and other designs in wood surfaces.

An electric router consists basically of a high-speed motor (usually 20,000 to 28,000 revolutions per minute) which is vertical-mounted in a housing that permits precise height adjustments. The housing has a flat circular base which glides easily over the wood, and the bottom end of the motor shaft is equipped with a special collet chuck which holds a cutting bit.

All bits have half-inch shanks and are generally interchangeable between brands.

The depth of cut is determined by how much the cutter projects down below the base of the unit, and this is set by raising or lowering the entire motor inside its housing after the bit has been inserted in the chuck at the bottom. The motor height is adjusted by a spiral cam or thread, or in some models by a rack-and-pinion arrangement. Either way, there are scale markings to indicate height, usually in 64ths of an inch.

Most routers have accessory edge guides which simplify guiding the tool along the edge of a piece of lumber, or which will guide it when cutting grooves across the face of the piece, or so far in from the edge that the guide will not reach, use an ordinary wood or metal straight-edge clamped to the surface as a guide. The base of the tool rides against this while it is moved along the line of cut.

In setting up the router for use, the first step is to insert the desired bit or cutter. These come in a huge range of different shapes and sizes. The bit is inserted in the chuck (make sure the electric plug has been pulled), then tightened in place with the wrench provided.

The tool is then set upright and the motor adjusted so that the bit just barely touches the surface on which it rests. The depty gauge is then set at zero, after which the beight adjustment can be manipulated until the router is set for the depth of cut desired.

Like most other power tools, routers come in different sizes or capacities - depending on the size and power of the motor.

Larger units, with motors of from 1 to 1 1/2 horsepower, will permit making deep cuts at a single pass, while smaller, home-size units (1/2 to 3/4 horsepower) may require making two or three passes when deep cuts are needed.

When using the router to cut moded edges, dados, grooves or rabbets, the tool should always be moved from left to right. This gives the smoothest cut with less chance of chipping or gouging because the cutter turns clockwise. On circular edges, move counterclockwise around the edge for the same reason. Actually, at the high speed at which the cutter rotates, a smooth surface will almost always by achieved.

Most routers come with fairly complete instruction books that ell how various cuts can be made, and how adjustments can be made to take care of various cutting situations. However, some practice is advisable on scrap material to get the "feel" of the tool, and to learn its capabilities and limitations.

One important point to keep in mind is that the tool should not be moved too fast; this could overload the motor, and tends to make the bits dull faster. On the other hand, moving it along too slowly might scorch the wood.

When starting the motor there will be a quick counterclockwise twist as it starts, so make certain the tool is gripped firmly with both hands. Although some experienced craftsmen can guide these freehand, this is seldom a good idea for beginners. A straightedge or guide should be used as a guide, and when making curved or patterned cuts it is best to use a template as a guide. This can be cut out of thin plywood or hardboard.

For making dovetail joints such as those used in assembling drawers, a special dovetail jig must be purchased. This is designed to grip both pieces of wood simultaneously so that a perfectly matching joint is achieved.

For trimming plastic laminate, there are special trimming cutters. These have a projecting pilot pin or bearing which guides the router along the edge and keeps it from gouging one surface while trimming the edge off on the other surface (for example, when an edge and top are both to be covered).