Heads Up!!!! Hot rivet coming in!.....
The hot rivet is driven into the hole with a few smacks with a big hammer. If you have to smack it too hard the rivet will bend, and you have to start over. Once the rivet is in place the "air buck" is placed over the head of the rivet, the other end is put against something REAL solid - in this case the frame of the engine we are working on is right next to us, the slack is taken up with an air cylinder, bracing the bucking bar solid so the rivet can be hammered on the inside of the firebox...