As a metalworking operation, turning is surely one of the most fascinating. The basic concept is so simple: a workpiece is made to rotate as a rigid tool is brought to bear along its length or across its face. The resulting form will be symmetrically shaped about its centerline. It will be wonderfully round.
Some of the oldest machine tools known to historians and archeologists are lathes. For power, many ancient designs used a treadle and bent pole or bow to pull a cord wrapped tightly around the spindle. Early metal cutting lathes produced elaborate bowls, tankards and candlesticks. Lathes were the instruments of craftsmen, their use strictly guarded by guilds.
The development of mechanical devices to hold and move the cutting tool, which occurred only a few hundred years ago, was one of the breakthroughs that ushered in the industrial revolution. Being able to control the longitudinal feed of the tool relative to workpiece rotation allowed lathes to do precise screw cutting. Precisely made screws, in turn, furthered advances in machine tool design and the creation of micrometers and other measuring devices. The lathe was coming into its own as a tool of industry and science.
Yet lathes and turning equipment have always been fun to watch. Perhaps it's the elemental appeal of rotating objects, the spinning motion that children find so engaging in tops and yo-yos. The object rotates yet its apparent shape always looks the same.
Workpieces on a lathe have this paradoxical appearance, too. When a cutting tool moves against this seemingly static workpiece, chips flow out almost magically, as if unwinding a strand of silver or unreeling a deep blue ribbon. The initial pass across a rough casting or piece of bar stock is especially remarkable. The dull surface that precedes the path of the tool gives way to a freshly turned profile so shiny and clean. No other machine tool works a transformation so dramatic and entertaining.
Even today's high-speed, high-powered CNC turning centers, which usually hide this vision behind Lexan dripping with coolant spray, notify us of their power with the machine gun sound of chips ricocheting against the sheet metal guarding.
No matter how you cut it, a lathe cuts with a unique style and grace. It should be everybody's favorite machine tool. Long live the lathe!