Rivet Installation Tools Hand Tools Rivet Cutter Bucking Bar Hand Rivet Set The various tools needed in the normal course of driving  and upsetting rivets include drills, reamers, rivet cutters or  nippers, bucking bars, riveting hammers, draw sets, dimpling  dies or other types of countersinking equipment, rivet guns,  and squeeze riveters. C-clamps, vises, and other fasteners  used to hold sheets together when riveting were discussed  earlier in the chapter. Other tools and equipment needed in the  installation of rivets are discussed in the following paragraphs. A variety of hand tools are used in the normal course of  driving and upsetting rivets. They include rivet cutters,  bucking bars, hand riveters, countersinks, and dimpling tools. The rivet cutter is used to trim rivets when rivets of the  required length are unavailable.  [Figure 4-82]  To use the  rotary rivet cutter, insert the rivet in the correct hole, place the  required number of shims under the rivet head, and squeeze  the cutter as if it were a pair of pliers. Rotation of the disks  cuts the rivet to give the right length, which is determined  by the number of shims inserted under the head. When using  a large rivet cutter, place it in a vise, insert the rivet in the  proper hole, and cut by pulling the handle, which shears off  the rivet. If regular rivet cutters are not available, diagonal  cutting pliers can be used as a substitute cutter. The bucking bar, sometimes called a dolly, bucking  iron, or bucking block, is a heavy chunk of steel whose  countervibration during installation contributes to proper  rivet installation. They come in a variety of shapes and sizes,  and their weights ranges from a few ounces to 8 or 10 pounds,  depending upon the nature of the work. Bucking bars are  most often made from low-carbon steel that has been case  hardened or alloy bar stock. Those made of better grades of  steel last longer and require less reconditioning.  Bucking faces must be hard enough to resist indentation and  remain smooth, but not hard enough to shatter. Sometimes,  the more complicated bars must be forged or built up by  welding. The bar usually has a concave face to conform to the  shape of the shop head to be made. When selecting a bucking  bar, the first consideration is shape.  [Figure 4-83]  If the bar  does not have the correct shape, it deforms the rivet head;  if the bar is too light, it does not give the necessary bucking  weight, and the material may become bulged toward the shop  head. If the bar is too heavy, its weight and the bucking force  may cause the material to bulge away from the shop head.  This tool is used by holding it against the shank end of a rivet  while the shop head is being formed. Always hold the face  of the bucking bar at right angles to the rivet shank. Failure  to do so causes the rivet shank to bend with the first blows  of the rivet gun and causes the material to become marred  with the final blows. The bucker must hold the bucking bar  in place until the rivet is completely driven. If the bucking  bar is removed while the gun is in operation, the rivet set  may be driven through the material. Allow the weight of the  bucking bar to do most of the work and do not bear down  too heavily on the shank of the rivet. The operator’s hands  merely guide the bar and supply the necessary tension and  rebound action. Coordinated bucking allows the bucking bar  to vibrate in unison with the gun set. With experience, a high  degree of skill can be developed. Defective rivet heads can be caused by lack of proper  vibrating action, the use of a bucking bar that is too light or  too heavy, and failure to hold the bucking bar at right angles  to the rivet. The bars must be kept clean, smooth, and well  polished. Their edges should be slightly rounded to prevent  marring the material surrounding the riveting operation.  A hand rivet set is a tool equipped with a die for driving a  particular type rivet. Rivet sets are available to fit every size  and shape of rivet head. The ordinary set is made of  1 ⁄ 2-inch  Figure 4-83.  Bucking bars.  Figure 4-82.  Rivet cutters. 4-36