5-9 Select a router bit that's the same diameter as the width of the mortise you want to make. Mount it in the router and adjust the depth of cut to cut no more than l/s -lA inch at one time. Secure a fence or straightedge to the router table to guide the workpiece. Hold the work-piece firmly against the fence with the area to be mortised above the bit. (If possible, let one end of the work-piece rest on an edge of the table.) Turn the router on and carefully lower the workpiece onto the bit.
5-10 Feed the work to the right until the left-hand mark on the workpiece lines up with the left-hand mark on the router table. Then feed it back to the left until the right-hand marks line up. As you re cutting, keep the stock firmly against the fence or straightedge. Finally, turn off the router and let it come to a complete stop before removing the workpiece. Note: A foot-operated switch is very handy for this operation.
Finally, you can use a mortiser or a mortising attachment to make a mortise. As mentioned previously, a mortiser makes a square hole. Drill a series of overlapping square holes to form the rectangular mortise. (See Figures 5-11 and 5-12.) Of the three methods, this requires the most setup time, particularly if you have to mount the mortising attachment on a drill press.
But it eliminates all hand work; you don't have to clean up the mortises with a chisel. If you make a lot of mortises, this will save time. The drawback is that a mortiser is a finicky tool that must be set up and operated with special care. Refer to "Using a Mortiser" on page 69 for more information.
5-11 Use a mortising attachment on a drill press to bore a row of overlapping square holes, in much the same way you would bore overlapping round holes. These holes will form a mortise without your having to clean up the sides or square the ends.
A mortiser drills a square hole by combining the action of a chisel and a drill bit. A square, hollow-chisel attaches to the drill press quill and moves up and down. A bit mounts in the chuck and spins inside the chisel. As you feed both cutting tools into the wood, the bit drills a round hole and the chisel trims it square. The edges of the chisel are beveled to direct the chips into the bit, which carries them up and out of the way.
-J- In setting up a mortiser, employ a fence to guide the work-piece. Use a small square to position the chisel so the front and back surfaces are parallel to the fence. If they aren't, the sides of the mortise won't be straight. Adjust the mortisefs hold-down to keep the stock flat on the table. Otherwise, you'll find it difficult to retract the bit.
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