What is back riveting, and is it a better way to set rivets?
Back riveting is a method of setting a flush rivet by hitting the shop side of the rivet with the rivet gun rather than the flush side. To back-rivet you need to have either a flat smooth plate on a table and lay the skin on top of the plate, or a bucking bar with a large surface area to push against the skin. On the shop side of the rivet you can use a rivet gun with either a cupped rivet set so the set does not slip off the rivet, or a back-rivet set. The back-rivet set is simply a rivet set with a spring collar on the end. The spring and collar push the substructure and the skin together to eliminate the gap between them and keep the skin tight to the plate or bar. Using a regular set it is necessary to press on both sides of the rivet with your fingers while riveting.
In conventional flush riveting the rivet gun has a flush set held against the factory head of the rivet. On the shop side a bucking bar is held to set the rivet and the gun impacts the factory side as well as the surrounding skin. If the bucking bar is not the right weight either a dent into the skin will occur or the rivet will sit slightly high in the dimple, depending on weather the bar is too light or too heavy. With back riveting everything is held tight to the plate or bar and the pressure on the skin side is spread out over a larger surface so no deformation is possible. The impact from the rivet gun and through the set is all on the shop side of the rivet rather than the factory side.
When working alone back riveting will result in a cleaner finished product. It works especially well on control surfaces because the skins are thin and the chances of deformation are higher.
© Cleaveland Aircraft Tool 02-26-01