the weld bead. Weave beads are often used as the fi nal pass of a multiple-pass weld. Right-handed welders generally make welds from left to right. Left-handed welders commonly progress from right to left. The electrode and electrode holder are held perpendicular (at 90°) to the weld axis. The electrode holder leads the welding end of the electrode. The electrode holder is tilted about 20° from perpendicular in the direction of travel. See Figures 12-9 and 12-10. Watch the shape of the ripples that form at the rear of the weld pool. The weld bead should have oval-shaped ripples (as shown in the top view of Figure 12-9) that are closely, and evenly, spaced. Pointed ripples indicate that the forward speed is too fast. Flattened ripples indicate that the travel speed is too slow. There are a few techniques that can be used when running a weld bead and when welding a joint. A continuous forward motion is one method used to make a quality weld. A repeating forward motion with a brief pause is another. This technique will produce uniform ripples on the face of the weld. Keep the following items constant while welding: • The arc length. • The electrode angle. • The weld bead width. • The forward welding or travel speed. The arc will stop if the arc length is allowed to become too large or if the electrode touches the base metal. Describing the Electrode Angles Two angles are used to describe how to hold or position an electrode in any arc welding process. These two angles are the travel angle and the work angle. To illustrate travel angles and work angles, two types of welds are shown in Figure 12-11 and Figure 12-12, a butt joint and a corner joint. In a corner joint or a T-joint, the edge of one piece butts up against the surface of the other. Thus, one is the butting piece and the other is the nonbutting surface. Travel Angle The travel angle describes the position of the electrode as it is tilted along the weld axis. It is the angle between a line perpendicular (90°) to the weld axis and the axis of the electrode. This angle is measured in a plane determined by the electrode axis and the weld axis. Figure 12-11 shows how the travel angle is measured. Note The correct way to describe the electrode position is to use the travel angle. However, sometimes the position of the electrode is described as an angle off the surface of the workpiece. Refer to Figure 12-9. Goodheart-Willcox Publisher Figure 12-8. Suggested dimensions for stringer and weave beads. The stringer bead is two to three times as wide as the electrode diameter. A weave bead should not be wider than six times the electrode diameter. Stringer Bead 3/8 in. (9.6 mm) 3/16 in. (4.8 mm) 1/8 in. (3.2 mm) Electrode Weld axis Weld axis Weave Bead 3/4 in. (19.2 mm) 3/8 in. (9.6 mm) 1/8 in. (3.2 mm) Electrode Motion Goodheart-Willcox Publisher Figure 12-7. The width of a SMAW stringer bead should be two to three times the electrode diameter. After welding for a short distance, check the bead width by comparing it with two of the electrodes being used. 172 Section 2 Shielded Metal Arc Welding Copyright Goodheart-Willcox Co., Inc.