398 Section 6 Oxyfuel Gas Processes Copyright Goodheart-Willcox Co., Inc. Goodheart-Willcox Publisher Figure 26-11. Recommended procedure for cutting thin steel. Notice that the two preheat flames on this tip are in line with the kerf. Direction torch movement Side View 15°–20° Front View Torch Position The torch angle for cutting varies with the thickness of the metal. The centerline of the cutting tip should be perpendicular to the surface of the metal to form square edges. The cutting tip should be tilted backward 5°–20° from vertical when cutting with the correct size tip, Figure 26-9. This push angle allows the welder to see into the kerf. As the thickness of the metal increases, the cutting tip should be held closer to vertical and not tilted backward. When cutting very thick metal, the work angle should approach 0° so that the cutting tip is nearly vertical, Figure 26-10. When cutting very thin metal (under 1/8″ [3 mm] thick), even the smallest tip size available may produce too much heat for a quality cut. In this case, increase the torch angle to 70°–75°, or 15°–20° from horizontal. This angle increases the amount of material being cut and allows a larger tip to produce a clean cut, Figure 26-11. Direction of travel 1/16" to 1/8" (1.6 to 3.2 mm) Uncut Kerf Side View Front View Goodheart-Willcox Publisher Figure 26-10. A student is practicing oxyfuel gas cutting on thick 1 1/2″ (38 mm) mild steel. Goodheart-Willcox Publisher Figure 26-9. The cutting head and tip are tilted away from the direction of cutting at a 5°–20° angle from vertical.