A rabbet is one of the most basic of cuts. commonly used in a corner joint or to accommodate the back of a cabinet. Few tools do the job better or more quickly than a router. As shown below,-a rabbet can be routed with a piloted rabbeting bit, although a straight bit in conjunction with an edge guide will work equally well. With a piloted bit, the pilot bearing rides along the edge of the workpiece while the cutting edges above the bearing rout the stock. The width of the rabbet is equal to one-half the difference between the diameter of the bit and the diameter of the bearing.
A 1 l/4-inch diameter bit with a 1/2 inch bearing, for example, will cut a rabbet 3/8 inch wide.
So that woodworkers do not have to own a different bit for each possible rabbet, many router bit manufacturers now sell rabbeting router bit sets, consisting of a single cutter and a selection of different-sized bearings.
A straight bit and an edge guide can be used to cut rabbets of any width: The cutter can be positioned at any distance from the edge of the stock. To rout extra-wide rabbets that exceed the capacity of your largest bit, make two or more passes, adjusting the location of the edge guide each time.
Note: A rabbeting bit carves a stopped rabbet into the underside of a shelf. The rabbet will fit into a wooden shelf support attached to the side of a car-case. This technique conceals both the rabbet and the shelf support.
Using a piloted bit to make a rabbet cut
Clamp your stock to a work surface; for the door frame shown, about one-half of the workpiece should extend beyond the table’s edge. Gripping the router firmly with both hands, butt its base plate on the workpiece and guide the bit into the stock; make sure the cutting edge is clear of the table. Keeping the pilot bearing pressed against the edge of the workpiece, feed the bit around the perimeter of the frame in a counterclockwise direction. Once the bit nears the table on the other side of the workpiece, stop the cut and turn off the router. Loosen the clamps, rotate the workpiece, and clamp it again. Follow the same routing procedures to complete the operation.
Build yourself a rabbeting jig
Make it easy to cut wide or non-standard-width rabbets with a straight bit and the simple jig shown at right. Made from two strips of wood, the jig is simple to assemble and set up. Cut the base from plywood or solid stock the same thickness as your workpiece. Make the edge guide from 3/+-inch plywood. Both pieces should be at least as long as the largest piece you plan to cut.
To set up the jig, secure the stock to a work surface and outline the rabbet on it. Butt the jig base against the edge of the stock. Align the bit over the cutting mark, then position the edge guide flush against the router base plate. Fasten the edge guide to the base of the jig with countersunk screws, ensuring that both boards are parallel to the edge of the workpiece. Clamp the jig in position. ln making the cut, feed the bit against the direction of bit rotation and keep the tool’s base plate pressed firmly against the edge guide throughout the operation.
Router table technique: