230 Modern Welding Copyright Goodheart-Willcox Co., Inc. 8.12.2 Fillet Weld on a T- or Inside Corner Joint Hold the welding gun at a 45° work angle when weld- ing fi llet welds in the vertical position. Short circuiting transfer and pulsed spray transfer are the best trans- fer methods for vertical welding. Stringer and weave beads are both used. Weave patterns include the oval, Z-weave, W-weave, and other patterns. Metal thicknesses of 1/8″ (3.2 mm) and thicker are welded uphill. When welding uphill, a push travel angle of 5°–15° is a good angle to use. Figure 8-64 shows a two-pass uphill fi llet weld. Metal thinner than 1/8″ (3.2 mm) is welded downhill. A drag travel angle of 10°–25° is used when welding downhill. 8.12.3 Groove Weld on a Butt or Outside Corner Joint On thin metal, weld vertical groove welds downhill with a drag travel angle. Keep the arc centered on the leading edge of the weld pool. Thin sheet metal, includ- ing auto body metal, HVAC ducts, and other sheet metal parts, do not require a root opening. Set the weld- ing wire feed and voltage for short circuiting transfer. Thicker metal still uses a downhill root pass. For the root pass, a 5°–15° drag angle is used. After the root pass, the intermediate and cover passes are welded uphill. See Figure 8-65. A keyhole at the root of the weld indicates that both pieces of base metal are melting and complete penetration is obtained. Do not position the welding gun directly over the root opening. The electrode wire will feed through the opening and create whiskers. GMAW and FCAW intermediate weld passes are welded uphill, often with a weave motion. Three passes in a thick groove weld are shown in Figure 8-66. Goodheart-Willcox Publisher Figure 8-64. A 3/8″ (9.6 mm) fillet weld is being welded on 3/8″ (9.6 mm) thick metal. The joint is being welded vertically uphill. The gun is pointed upward at 5°–15° and has a 45° work angle. A B 5°–15° Goodheart-Willcox Publisher Figure 8-65. A V-groove weld on a butt joint. The second of multiple passes is in progress. A 5°–15° push travel angle is used when GMAW or FCAW welding uphill.