Small Tools for Tiny Turnings
You Can Make Them Yourself
When turning miniature vessels, such as the small scale bowls on pages 52-55 of issue 74 (below) of WOOD Magazine, you often run into situations you just can't handle with regular gouges and scrapers. To reach in through a narrow neck to clean out an interior, for instance, a thin, round-nosed tool with a bend in it would be great. But where do you get such a thing? Well, you could make one.
"It's both easy and satisfying to create the tool you need for a particular job," says woodturner John Lea of Mesa, Arizona. All you need are a standard bench grinder and some allen wrenches. "I like allen wrenches because they come in such a range of sizes, they're inexpensive, and they seem to be made of pretty good steel," John sums up.
The procedure is simple: Grind a beveled scraper-type end on an allen wrench, forming a profile to meet your needs. (You also could make tools from screwdrivers or dental instruments.) Then, fit the tool with a handle, such as a length of dowel or a turned piece.
"You should consider a few fine points when you grind your own tools," says John, who makes and sells full-sized turning tools as a sideline. Here's his advice:
- Select the largest allen wrench that fits your project. This provides the rigidity and mass needed to dampen vibration. Reduced vibration leads to a smoother cut.
- Start by grinding a reference surface for the cutting edge, where shown below, top. Grind this flat area two or three wrench-diameters long and parallel to the wrench's axis.
- Grind a bevel on the cutting end of the least 10° as shown below, bottom. This relief, called the rake angle, provides clearance so that the tool doesn't rub when the cutting edge contacts the workpiece. In some cases, say interior work on a small-diameter vessel, you may need a rake angle greater than 10°. But always keep the angle as shallow as possible. "If it's too great," John explains, "the cutting tip will be too thin and will flutter as it cuts, creating ridges and hollows."
- In use, the small tool requires solid support. To keep it from rocking, John grinds the bottom flat where it rides on the tool rest. Support it as close to the cutting edge as possible to minimize vibration, too. "I sometimes modify my tool rest or clamp an extension onto it when necessary to give the small tool the best possible support," John adds.
Illustrations: Kim Downing