Pipe wrench Pipe wrench A pipe wrench is any of several types of wrench that are designed to turn threaded pipe and pipe fittings for assembly (tightening) or disassembly (loosening). Especially in North America, the Stillson wrench or Stillson-pattern wrench is the usual form of pipe wrench. (The name comes from the original patent holder, who licensed the pattern to multiple manufacturers; the patent expired decades ago.) Another type of wrench often used on pipes, the plumber wrench, is also often called a pipe wrench, depending on locale. The Stillson type is an adjustable wrench/spanner with hardened serrated teeth on its jaws;
Machine tool it is "economically practical" to make them only with machine tools. In the 1930s, the U.S. National Bureau of Economic Research (NBER) referenced the definition of a machine tool as "any machine operating by other than hand power which employs a tool to work on metal". The narrowest colloquial sense of the term reserves it only for machines that perform metal cutting—in other words, the many kinds of [conventional] machining and grinding. These processes are a type of deformation that produces swarf. However, economists use a slightly broader sense that also includes metal deformation of other types that squeeze the