232 Modern Welding Copyright Goodheart-Willcox Co., Inc. 8.13.2 Groove Welds Figure 8-69 and Figure 8-70 show the angles used to weld a butt joint and an outside corner joint in the overhead welding position. The root pass is similar to other welding positions. Keep the arc centered on the weld joint and toward the front of the weld pool. Watch the keyhole to ensure both pieces are melt- ing. A 5°–15° drag travel angle is used. Even though the weld is overhead, a slight weave can be used. A small weave may be needed to bridge a wider root gap. After the root pass, a small weave is used for the intermediate passes. 8.14 Automatic GMAW and FCAW Gas metal arc welding and fl ux cored arc welding can be semiautomatic or fully automatic processes. In the semiautomatic process, the welder must direct and move the gun while the welding wire feeds automati- cally into the weld pool. Both GMAW and FCAW guns can be mounted on a motor-driven carriage or robot. See Figure 8-71. The pro- cess is fully automatic if the welding gun is controlled by a machine with feedback controls. Chapter 26, Automatic and Robotic Welding, presents more information about robots and other automatic welding equipment. A B Direction of travel 5°–10° travel angle Cover pass Root pass Goodheart-Willcox Publisher The Lincoln Electric Company Figure 8-69. A—Bevel-groove weld on a butt joint in an overhead welding position being completed in two passes. B—A welder using FCAW–S to make a bevel-groove weld in the overhead welding position. Front View Side View 5°–10° travel angle Goodheart-Willcox Publisher Figure 8-70. A J-groove weld in an outside corner joint in the overhead welding position. Motoman, Inc. Figure 8-71. A GMAW gun mounted on a robot. The part is held in a fixture.