What's the best way to add threaded wood bolts and nuts?
I'd like to incorporate threaded wood bolts and nuts into an upcoming project. Is this a difficult process to set up and learn?
—John Schroeder, Evansville, Indiana
To answer your question, John, we tried out two threading systems and got good results with both. The first is a hand-powered thread box with a V-shape cutter that slices the threads into a dowel. We found a 3⁄4 " die (item #G1868) from Grizzly Industrial, 800/523-4777. You also can purchase a tap for making 3⁄4 " threaded holes (item #G1869). To use the thread box, apply slight downward pressure for the first few turns. After that, the wood thread engages the nut inside the thread box and begins feeding itself. If you just want to try threaded dowels, the manual thread box will get you started and make clean cuts in straight-grained woods.
The Beall Wood Threader from Beall Tool Co. (800/331-4718) uses a router to drive a carbide bit supplied with the threader kit. This jig must be set up precisely to work properly. Before you cut the threads, follow the directions to tap a sample hex-nut. This serves as a guide for setting the router's depth of cut. Don't aim for too tight a fit because any change in the moisture content of the wood might hamper assembly. Prices range from $80 for a 1⁄2 " threader to $275 for a set to do six sizes.
The Beall tool also lets you make smooth cuts even in difficult materials. We found the Beall tap easy to start squarely because an unthreaded pilot engages the hole before the bit begins cutting. You can remove the pilot to convert the tool into a bottoming tap that cuts threads nearly to the bottom of a hole.