Abstract: A low-voltage electromagnetic riveter (LVEMR) including two opposed rivet guns (70, 72) for upsetting rivets during the assembly of structural parts is disclosed. Variable capacitor banks (64, 65 or 64', 65') are discharged to provide a variable current pulse which flows through a driver coil (131) and a mass-mounted coil (135) of each rivet gun (70, 72). Preferably, the mating faces of the coils are contoured to assist in the alignment of the coils. The driver coils are affixed to the ends of drivers (125) that drive rivet dies (121) into the ends of a rivet (75) to be upset. The LVEMR is controlled such that the net magnetic forces generated between the two pairs of coils actuate the rivet guns (70, 72) so that one end of the rivet is impacted slightly before the other end. The delay is controlled by a delay generator (44). Further, rapid-acting ground fault detection circuits (52 and 53) cause a power shutdown and capacitor bank discharge in the event of a ground fault.