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Planishing is a technique used to curve and shape thin pieces of sheet metal. The process involves tapping the metal with a specialized planishing hammer while it rests on a rounded stake in order to smooth defects and achieve the proper curve. Planishing is commonly performed in auto body shops, airplane manufacturing plants, and many other industrial metal fabrication settings. In the past, workers would planish sheets by hand, but most experts today make use of pneumatic or electrical machines to quickly and precisely shape metal parts.
Metalworking has been a common practice around the world for many centuries, and blacksmiths have utilized planishing tools to create sword handles, metal bowls, and suits of body armor. Today, professionals planish metal sheets to fabricate car fenders, gas tanks, airplane bodies, and decorative pieces like lamps. Many amateurs and hobbyists also use the technique in their own shops while restoring vehicles or crafting decorative jewelry.
After forming a sheet into its basic final shape using cruder metalworking techniques, an expert places the material over a stake or anvil and hammers out the small imperfections. The planishing stake is basically a small metal sphere on top of a rod that is secured to the floor. Several different hammers can be used, depending on the type of metal and the level of perfection the worker hopes to achieve. Some experts use large wooden mallets and ball-peen hammers in their work, while others employ planishing hammers that are specially designed for the task.
Small dents or raised edges in a metal piece are tapped with the planishing hammer and smoothed along the curve of the stake. It commonly takes several hundred taps to work a sheet to perfection. By carefully aligning the piece on the stake, a metalworker can achieve nearly any desired shape. A professional can manipulate a sheet to create a long, steady curve or nearly round it into a flawless circle if desired.
Metal is planished using machines in most modern auto body shops and manufacturing plants. A pneumatic or motor-controlled planish machine can accomplish a more precise finished product in a fraction of the time and effort required with hand tools. A worker aligns the metal piece and controls the hammer with a foot pedal or hand trigger. Using air pressure or electrical power, the hammer lightly taps the sheet several times a second. The worker must simply push and pull the metal piece by hand during the job to work the entire sheet.