Abstract: A machine which forms pipe elbows and other curved conduits by spirally winding a thin strip of sheet metal. The machine includes spaced apart cutting rollers which are reciprocated toward and away from one another by cams in order to cut the strip into a series of interconnected gores having contoured edges. The contoured edges are progressively bent in a manner to interlock by sets of bending rollers that are reciprocated inwardly and outwardly by cams. The strip is spirally wound inside of a ring shaped winding shoe having dies which interlock the opposite edges of the strip. Crimping rollers act to firmly crimp together the interlocked edges to form an acme seam. Clutches permit the cams to be selectively stopped so that the conduit that is formed can be provided with both straight and curved portions.