Chapter 8 Gas Metal and Flux Cored Arc Welding 225 Copyright Goodheart-Willcox Co., Inc. When the trigger on the gun is pulled, an arc forms, and a C-shaped weld pool is created. Point the electrode more toward the surface if the edge begins to melt too quickly. Adjust the position of the gun to maintain a C-shaped weld pool. Weld at a constant speed. Maintain the weld pool at the same size. With practice, you will master gun angles, travel speed, and weave motions to produce a uniform width bead with uniform ripples in the weld face. See Figure 8-50. Backtrack over the completed weld for about 1/4″ (6 mm) when the end of the joint is reached. This move- ment helps fi ll the crater that occurs if the weld is stopped at the end of the joint. No matter what type of weld is made, this same fi nish movement can be made. Backhand welding with a 15°–25° drag travel angle allows for good weld bead control and produces good penetration. When welding on thin base metal, backhand welding can burn through the base metal. Switch to forehand welding on thin metal. The penetration in forehand welding is less than the penetration in backhand welding, as shown in Figure 8-45. Forehand welding using a push travel angle provides the least penetration. Holding the gun perpendicular to the weld joint gives moderate pen- etration. Backhand welding using a drag travel angle provides the greatest penetration. This applies to all welding joints and positions. 8.10.2 Fillet Weld on a T- or Inside Corner Joint Fillet welds are made on T-joints and on inside corner joints. Good penetration into the root of the joint is obtained because of the deep penetration possible with the spray transfer method. The work angle should be held at a 45° angle to each metal surface. If the backhand welding method is used, the electrode and gun are held with a 15°–25° drag travel angle. See Figure 8-51. Figure 8-52 shows a fi llet weld made using the work and travel angles described. The GMAW and FCAW processes can generally be used to weld 1/4″ (6 mm) beads, leg size, on each pass. If the weld must be more than 1/4″ (6 mm) thick, two or more weld passes are required. Goodheart-Willcox Publisher Figure 8-50. Lap joint with uniform weld bead width and ripple spacing. Direction of travel 15°–25° travel angle 45° from surface Goodheart-Willcox Publisher Figure 8-51. A fillet weld on an inside corner joint in the flat welding position. The electrode is 45° from each metal surface. It is also tipped 15°–25° in the direction of travel. Goodheart-Willcox Publisher Figure 8-52. A completed fillet weld done in the flat position.