Popular Woodworking 2003-06 № 134, страница 38
Ingenious Jigs Drill Press Mortising Chisel Simpler is better. Way better. Once upon a time, back before all these funky little benchtop mortisers were available, the only tools worthy of the name "mortiser" were industrial behemoths that looked as if they were welded together from spare tank parts. For the small-shop guy who wanted to drill square holes, the tool companies offered a "drill press mortising attachment," an accessory whose name was more of a practical joke than an accurate description of its capabilities. A hollow mortising chisel requires a great deal of pressure to bore a square hole, and most drill presses do not provide the necessary leverage for the job. However, a drill press does provide enough leverage to cut a mortise with an ordinary chisel. In fact, if we were to go back one more generation of mortising machines, you'd see that 19th-century mortisers looked a great deal like drill presses with chisels in place of bits. You simply placed the chisel over the wood, then used a hand- or foot-operated quill to press the chisel into the wood. Making a Mortising Chisel for Your Drill Press To cut with a chisel mounted in your drill press, the back of the chisel has to be parallel to the axis of the quill. If it isn't, the cut will drift and your mortises will be angled. Consequently, one of the best chisels you can adapt to your drill press is one that was designed for it - a hollow mortising chisel. Its back is perfectly true to the action of the quill. You can't use it as designed, but with a few minor modifications, you can make a useful tool out of it. Grind away the front and sides of the chisel, leaving just the back. On the chisel shown, I exposed about 21/2" inches of the back - I rarely cut mortises more than 2" deep. If you cut deep mortises, you might have to grind more metal. Sharpen the tip by Nick Engler Nick Engler, the author of more than 50 books on woodworking, is currently building a replica of the 1903 Wright Flyer, the first true airplane. of the chisel as you would an ordinary flat chisel, but increase the angle of the bevel slightly. Bevels between 35° and 40° work best when chopping mortises. There are two ways to mount the chisel on your drill press. You can use the yoke that came with the drill press mortising attachment, but this will make it difficult to change the orientation of the chisel when you want to switch from cutting the sides of the mortise to cutting the ends. Instead, I prefer to mount the chisel in the chuck so you can rotate it where you need it. I found 36 Popular Woodworking June 2003 |
