Chapter 15 Oxyfuel Gas Cutting 423 Copyright Goodheart-Willcox Co., Inc. To start a cut on thick plate faster, the welder begins at the edge of the metal, slanting the torch in the direction opposite the direction of travel. See Figure 15-23A. As the edge is cut, the welder moves the torch to a vertical position, until fi nally the total thickness is cut, Figure 15-23B. The welder may then proceed with the cut. See Figure 15-24. Two other methods are used to start cuts. One is to nick the edge of the metal where the cut is to start with a cold chisel. The sharp edges of the nick heat up and oxidize rapidly when the cutting torch is applied. This makes it possible to start cutting without preheating the entire edge of a thick plate. The second method is to place an iron fi ller rod under the preheating fl ames at the edge of a thick plate. The fi ller rod reaches the cherry red temperature quickly. The rod oxidizes and causes the thicker plate to start oxidizing when the cutting oxygen is turned on. Figure 15-25 shows a welder cutting a thick section. Special cutting torches are capable of handling the much higher volumes and pressures of cutting oxygen required for cutting very thick metal. See Figure 15-26. A B Goodheart-Willcox Publisher Figure 15-23. Steps for starting a cut on thick metal. A—The correct oxyfuel gas cutting torch position for the starting cut. B—The required change in the torch position as the cut progresses. Goodheart-Willcox Publisher Figure 15-24. Cutting straight lines in the horizontal, vertical, and overhead position requires much practice. This welder is practicing on 3/8″ (9.6 mm) steel plate in the horizontal position. Victor, a division of Thermadyne Industries, Inc. Figure 15-25. A skilled welder uses a cutting torch to make an accurate cut on 4″ (10 cm) thick steel.