Wooden Screws

Cutting wooden threads is always associated with woodturning. At the very least, the screws begin as cylinders before threading with hand screw boxes. Eighteenth-century woodturning manuals give thorough instructions on making screw boxes and other devices for cutting both large and small screws. I have included translations of these in the Appendix as Plans A and B.

Along with the screw boxes and special screw-cutting lathes, these books illustrate chasing tools — scrapers with teeth spaced at the pitch of the desired thread. As the wood turns, you deftly sweep the tool across the cylinder and strike a set of spiraling threads. Once the first threads are cut, they guide the chasing tool along, cutting subsequent threads down the cylinder.

Chasing threads is more commonly done in smaller works such as the internal and external threads for lidded boxes, but you can also chase the threads for a two- or three-inch bench vise screw. Diderot shows such a large chase in the section of the Encyclopédie on turning, and an excellent blacksmith forged a duplicate for me using the scale provided in that eighteenth-century book. The five scraper teeth are 7/16-inch equilateral triangles, all sharpened as scrapers except the rightmost one. I dubbed over that tooth's edges to keep it from cutting, but retained its shape. This safe tooth can ride against an existing thread and push the cutting teeth along, advancing the spiral.

The five scraping cutters create beaucoup drag, but the spring-pole lathe has the power to roll a dried hickory blank right through it, sliding the chase down the tool rest with every turn. In theory, you can strike the first thread with that single deft sweep of the tool. I don't even try, and give the first few inches of the screw a hand-sawn and -rasped starter thread—as explained in the translation of Salivet's description of cutting large screws. Once the chase gets a purchase in the first spiral, every turn pushes the chase to the left, duplicating the first thread. Held lightly at an angle, the teeth to the left scratch a gradually deepening spiral. As each section reaches full depth, you give the chase new footing and copy that completed section farther down the screw. The threads cut by the chase are only as good as the first spiral. If there's a wobble in it, that wobble is copied all the way down the length of the screw. The old masters called this a "drunken screw."

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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