A pole lathe is a predecessor to the electrically-powered wood turning lathe found in many home and commercial woodworking shops. The pole lathe looks similar to the modern powered lathe, but instead of an electric motor, the power to turn the wood comes from a foot treadle operated by the turner, the person operating the lathe and making cuts in the turning wood. The pole provides the power to return the treadle to its starting position. It takes significantly longer to turn wood on a pole lathe than on an electrically-powered lathe, but a good turner can produce high-quality work on either machine.
Specifically, when the workpiece is secured in the lathe, a piece of rope, twine, or leather is wrapped around it two or three times, with one end attached to the foot treadle and the other to a pole stretched overhead. The pole should be green and springy, because it's the springiness that makes the pole lathe work. When the treadle is pushed down by the turner's foot, the rope wrapped around the workpiece spins it and simultaneously pulls the pole down. When the treadle hits bottom, the turner releases his foot, and the pole springs back, pulling the treadle back to the start position. Modern-day pole lathes sometimes are made with a bungee cord instead of the greenwood pole, to avoid having to cut a new pole every couple of months.
When turning a piece of wood, for the leg of a chair or table, or a baseball bat, the first step is to make rough cuts to bring the workpiece to a roughly cylindrical shape. This is done to prevent edges and protrusions in the wood, which, when the wood is spinning, can slam into sharp cutting tools in the turner's hands. Sometimes this will break the workpiece irretrievably, and sometimes it will wrest the tool from the turner's grip, turning it into a missile. Thus, safety considerations dictate pre-forming the cylinder as much as possible before even securing it to the lathe and turning it.
When the rough cylinder has been made, the two ends are secured to chucks, which are free-turning parts of the lathe, made of wood or metal, that hold a workpiece in place while it's being turned. The chucks determine the workpiece's center, making the job of securing the workpiece one that must be approached with deliberation and care. A poorly centered workpiece often must be scrapped, wasting material and time.
When the workpiece has been secured, the rope is wrapped around it, two or three turns, and attached at one end to the foot treadle and at the other end to the pole overhead. When the treadle is pressed down, the workpiece spins toward the turner, who presses cutting tools into the turning workpiece, using the tool rest on the lathe as a support. Cuts can only be made while the treadle is being pressed down, because the spring action of the pole supplies just enough energy to raise the treadle to its starting position, and efforts to cut the workpiece during this return phase will just slow or stall the process. Thus, when the treadle can't be pressed down any further, the turner releases it, and the overhead pole springs back to its original position, pulling the treadle back up to its starting position.
An experienced pole lathe turner can build up a good deal of torque, but the torque developed with a pole lathe doesn't approach that of an electrically-powered lathe, making the job of turning wood on a pole lathe more time-consuming, as well as more physically demanding. Nevertheless, many woodworkers make a point of becoming proficient in the operation of non-electric tools, and are capable of turning wood on a pole lathe that's indistinguishable from that mass-produced in a factory.