Sorting through router bit terminology and making selections from a seemingly endless variety can be confusing, especially if you are new to working with a router. Reading up on the basic facts will help you to choose the best router bits, and to make the best use of them.
There are numerous types, including many designed for highly specialized applications. We won't be able to cover every type in this article, but here are some of the most common:
Straight Router Bits
Straight router bits are among the most common frequently used. Straight bits used to make cuts straight down into a material to form a groove or dado or to hollow out an area for a mortise or inlay. They come in a variety of cut diameters, most commonly in the range from 3/16" to 1-1/2".
Rabbeting Router Bits
Rabbeting router bits produce a straight vertical and horizontal cut, and are designed specifically to cut a rabbet (notch) in the edge of a material. Rabbeting is an example of a "piloted" bit, meaning that a bearing of the top of the bit is used to guide that along the edge of the material. Rabbeting bits usually come in a set that includes a range of pilot bearing diameters, allowing a single one to produce a variety of rabbet dimensions.
Flush Trim Router Bits
Flush trim router bits are guided by a pilot bearing that is the same size as the bit's cutting radius. They're used to trim the edge of one material flush with the edge of another material. Trimming a veneered surface flush with a substrate, or using a pattern to create multiple identical shapes are examples. The pilot bearing may be on the top of the bit, at the base of the cutting edge, or both.
Chamfer Router Bits
Chamfer Router Bits produce a bevel cut at a given angle. Chamfer's are sometimes used to decorate the edge of a material, and can also be used in joinery to create beveled edges for multi-sided constructions.
Edge Forming Router Bits
Edge forming router bits are most often used to cut a decorative edge into a material. The variety of edge
forming profiles are practically unlimited, but some of the most common include:
• Round over bits - Used to cut a rounded edge of a given radius.
• Ogee bits - The term "ogee" refers to an "S" shaped profile. Ogee's are available in a number of configurations; the Roman ogee bit pictured here is one of the most common
• Edge beading bits - Used to cut a 1/4 or 1/2 half circle profile called a "bead" into an edge or corner
• Cove router bits - used to cut a concave 1/4 circle into a material
Many edge forming bits include a pilot bearing. In most cases, they are used for final decoration of a project where edges are already established and can serve as the guide for the bit.
Molding Router Bits
Designed to architectural molding profiles, molding bits are typically larger than the basic edge bit. Molding bits may incorporate multiple basic edge forming profiles into a single bit. Because of their size, molding such bits most safely used in a router table.
The Classic Multi-Form Bit pictured here is designed to make several decorative profiles possible by combining basic profiles included in a single one.
Stile and Rail Bits
These are used in frame and panel construction, primarily for constructing frame members of cabinet and passage doors. These bits cut a decorative profile and a panel slot into the edge of door frame stock, and also a corresponding cut into the end of the material where the frame's "rail" (horizontal member) meets the profiled edge of the frame's "stile" (vertical member).
These are available either as a set of two "matched" bits, or as a single that can be arranged to cut both of the necessary components of the cope and stick joint.
Raised Panel Bits
These are often used in conjunction with the previous type to produce a profiled edge on a door panel. The profiled edge fits into the corresponding slot in the frame's stiles and rails. Raised panel bits are available in both a horizontal and vertical configuration. Horizontal raised cut the panel profile with the panel stock laying flat on the table. A vertical frame and panel bit is used to cut the panel profile with the stock tipped up on its edge and run along a fence.
Vertical raised are considered by many to be safer to operate because of their much smaller radius. A horizontal raised panel bit is necessary for panels with curved edges, such as those used in arched top or "cathedral" cabinet doors.
Joinery Bits
These include dovetail, drawer lock, finger joint, and lock miter bits. Each of these is used to produce a specialized type of precision joint. A dovetail is often used in combination with a dovetail jig to quickly and accurately produce dovetail joints for drawer boxes and other box-making projects.
