A pop rivet gun is a tool used to set pop rivets into place. Usually offered in two types, pneumatic and hand-operated, the rivet gun is used in sheet metal fabrication where a welded seam is not required or is not practical. Pop rivets come in a variety of sizes and styles. They all share one common trait: a shank that resembles a long nail-like stem protruding out of the top of the rivet that is inserted into the jaws of the rivet gun. When pulled, the rivet gun draws the rivet head through the rivet body, expanding it so that it binds two or more pieces of sheet metal together.
The pop rivet gets its name from the telltale sound the rivet makes when tightened completely. As the gun tightens the rivet, the rivet head snaps off of the shank and makes a popping sound. The shank is then discarded from the rivet gun, and another rivet is inserted into the jaws to be set. While the pneumatic style of rivet gun is operated by a simple pull of a trigger, the hand-operated style is firmly squeezed until the rivet is set. This method of repetitive squeezing can become very difficult and tiring after only setting a few pop rivets.
The earliest rivets were solid steel pieces that resembled a bolt with a rounded head and a shank with no threads. This rivet was placed into a hole that had been drilled into a piece of steel, and the rivet gun was used to pound the protruding shank into a round ball similar to the rivet's head. As this was done, the shank was shortened and effectively tightened the rivet into place. The benefit of this type of steel construction was that there were no bolts to be mis-tightened or to rust through. This was the preferred method of fastening steel girders together prior to practical welding and was the fastening method used on bridges and skyscrapers worldwide.
The pop rivet used the same principle, however, the stem takes the place of the rivet hammer and forces the pop rivet's body to expand outward to create the bond. The rivet gun is primarily used in heating and cooling system installation to fasten the thin steel and aluminum sheet metal ducting material. The rivet hammer is typically used in aircraft and boat manufacturing where watertight and airtight seals are required in the sheet metal seams.