Dr. Wood Discusses:

Routers:

Remember that all power tools are potentially dangerous. Always wear eye and ear protection when using woodworking tools. Read and understand the manuals and instructions provided with your tools, and never use a tool in a way that endangers you or those around you.

The router is one of the more underutilized tools, and yet it is capable of doing more different jobs than any other tool in your shop. Most tools are designed for a particular purpose, and do not do other jobs well. For example, the table saw is a great machine for ripping and crosscutting boards to size, but it is not designed for cutting circles. However, the router has been adapted to a wide variety of jobs through the design of ingenious cutters and the addition of numerous shop-made and commercially available jigs. In this article we will discuss some basics of router design to help you choose the right tool for your needs.

The router is incredibly versatile. Originally designed as a hand-held molding and groove cutter, the uses for the motorized router have grown over the years until now this tool is used for cutting dados and grooves, adding edge details, basic and decorative joinery, adding relief patterns and inlays, cutting circles, and trimming laminate. There are hundreds, if not thousands of router bits of every shape and size on the market today, with new ones being introduced each year. Woodworking specialty stores should stock 200 or more different router bits. Combined with the necessary jigs and accessories, the router can perform nearly every task in many projects.

Another word about safety: A router demands respect from its user. The cutter speeds for routers without speed controls is 20-22,000 rpm, and smaller hand-held routers known as laminate trimmers can run as fast as 30,000 rpm. Therefore, inspect your bits for wear and flawed brazing of the carbide cutters. Inspect bits for damage to the shank, and keep the router collet clean and free of scratches to ensure that the router maintains a tight grip on the bit during use. Before we discuss the kinds of bits and cutters available for the router, lets talk a little about the different kinds of routers on the market today.

A router is nothing more than a motor that powers a circular cutter. Typically a router has a base with one or two handles, a power switch, and some type of depth control adjustment. The base holds a motor to power the bit, and the collet attaches the bit to the motor shaft. The depth of your cut is defined by how far out of the router base the bit extends, while the width and/or shape of the cut is determined by the bit you are using. Routers come with motors from less than 1 HP to over 3 HP. Small routers are fine for light edge routing, but don't expect these tools to do very well on larger jobs. Large routers (3 HP and up) are great for mounting in your router table where their power can be put to use, but the size and weight of most large routers make them unsuited for many hand-held routing applications. A happy compromise for a good, all-around router is a 2 HP to 2-1/4HP unit, which will give you adequate power without too much weight. A tool of this size can be used freehand or inverted in a router table to facilitate shaping on smaller pieces.

There are two basic styles of router on the market today, and they are characterized by the type of base that they have. The base is the flat bottom of the router in contact with the wood, and is usually an integral part of the body that holds the router motor in place. The traditional style is called a "fixed-base" router, to distinguish it from the new style "plunge-base" router. Plunge routers have a motor housing that is mounted on the base by way of an adjustable, spring-loaded mechanism. This allows the motor and housing, and thus the router bit, to be moved up and down during operation. The advantage of this movement is flexibility. You can easily make several sequentially deeper passes during a deep routing operation. You can also cut 'blind' dados and grooves using a plunge router. In contrast, most fixed base routers have a threaded or twist mechanism that adjusts bit exposure, and the bit sticks out of the base at all times. A fixed base router is ideal for edge detailing and ploughing grooves where a plunge mechanism is not needed. A new marketing approach for this sized router is to sell a dual-base system, consisting of a single router motor together with a fixed base (for the table) and a plunge base (for hand-held applications). Several routers have a micro-adjustable mechanism that allows movements of the bit with an accuracy of ±0.002 inches.

Look for a router that accepts 1/2" shanked bits and has variable speed control so that you can adjust your bit speed and feed rate to the wood you are cutting. An important safety consideration is to make sure that the plunge mechanism is the type that is locked, not open in the stand-by position. This will prevent unanticipated movement of the router bit during operation. Finally, make sure the tool feels good in your hands, with convenient controls and an appropriate weight and balance. It is dangerous to use a router bigger than you are capable of handling. If you decide on a fixed-base router, look for one with a sturdy housing, easily operated depth adjustment and conveniently located controls.

Router bits are the replaceable cutters that fit into the collet of your router. The router bit has a shank that fits into the collet of the router, and bits come with shanks of either 1/4" or 1/2" diameter. Shank and collet size are a consideration in selecting your router because the larger 1/2" shank bits are safer, particularly when larger bits are employed. The cutters are made of either high-speed steel or carbide. Steel router bits are less expensive, but they require more frequent sharpening and are not as available as carbide bits. The quality of the carbide will affect the ability of the bit to take and keep a fine edge. In general, bits made in the U.S.A. and those made in Italy and Israel are superior to Taiwanese products, but manufacturing processes and quality can vary greatly. The best solution is to buy your bits from a trusted source that has personal experience with the tools they are selling.

The shapes of router bits, and thus the jobs they do, vary greatly. Bits intended for cutting grooves and holes are generally straight with the cutter blades extending down around the bottom of the bit. Bits of this type are the straight, box core and dovetail bits. Alternatively, edge-cutting bits have a pilot or bearing on the end of the bit that allows the bit to travel along the edge of the board, thereby controlling the depth of cut. Lower quality bits will have a steel pilot, while better bits will have an interchangeable bearing. The ability to change bearings means that the depth of cut can be modified by changing bearings rather than needing to buy a new bit for every new cut. Edge cutting bits are exemplified by round-over, cove and beading bits, by ogee and other decorative trim cutters, by laminate trimmers, and by pattern cutters.

Another class of router bit that has found increasing popularity with the advent of larger, table-mounted routers are those used for raised-panel doors and wainscoting. The frame members of raised panel doors are called the rails and stiles. The job of cutting the pattern and cope in rails and stiles has traditionally been a job for the shaper, but routing these members can be accomplished with a table-mounted router fitted with a 1/2" collet. The larger collet capacity is necessary due to the large size of the router bits for this job. Bits are also available for cutting the raised panels in these projects. Two types of panel raisers are available for the router: horizontal and vertical. When using a horizontal panel raising bit the wood is laid flat on the table, face down, and passed over the bit. The depth of cut is controlled by the bearing on the bit. For vertical panel raisers the board is set on edge against a fence and passed by the bit. Vertical panel raisers can be made safer by using the router in the horizontal position, allowing the panel to again be laid flat on the table surface.

The many applications of the router make it the second most important power tool in any shop, after the table saw. Explore the many possibilities offered by this versatile tool by talking with someone familiar with routing, or by reading one of several excellent books available on the subject.