It'll be a familiar sight: on window sills, gutters, cake trays and window boxes, the sheet metal curls at the edge. That curl forms an attractive edge and gives the workpiece extra strength.
But to curl a sheet of metal into a round shape so neatly and evenly, you need a machine. One of the two curling machines here on the work table is no less than 170 years old! But basically, the way these machines operate hasn't changed in all that time. You take the sheet metal that is to be curled and clamp it width-wise into the machine. The edge is inserted into a groove in the curling bar, in other words, into the slot in a shaft. As the curling bar is turned by hand, it draws the sheet into the rotation and forms it into a hollow, circular shape – a curl. Once the operator has completed one full turn, they loosen the bar at the side, where it's secured, move it a little and can then ease the curled sheet sideways and remove it from the bar. Simple but effective!
All depictions: © Europäisches Klempner- und Kupferschmiedemuseum, Foto: Klaus Hofmann
