60 Shielded Metal Arc Welding Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. grip (do not hold it too tightly else your hands will tire quickly). Place the clamp section of the electrode holder toward your thumb. This will give you extra leverage for striking the arc and moving the electrode. Use two hands whenever possible, Figure 11-3. Before striking an arc, there are two angles that need to be determined: work angle and travel angle. Work angle is defi ned by AWS as “the angle less than 90° between a line perpen- dicular to the major workpiece surface and a plane determined by the electrode axis and the weld axis.” For example, an electrode held per- pendicular to the workpiece is at a 0° work angle, Figure 11-4. Travel angle leans in the direction of travel. According to AWS, travel angle is defi ned as “the angle less than 90° between the electrode axis and a line perpendicular to the weld axis, in a plane determined by the electrode axis and the weld axis.” Holding the electrode perfectly per- pendicular to the weld joint would be a 0° travel angle, Figure 11-4. The more the electrode is tilted downward toward the weld joint, the higher its travel angle. With a 0° work angle, lower the electrode to about 1″ (25 mm) above the work. Assume a 15° to 20° travel angle by leaning the electrode to a 15° to 20° angle from the vertical in the direc- tion of travel. This inclination is important. If the angle is more than 20°, the penetration may not be enough to produce a solid weld. Striking the Arc Lower your head shield and strike the arc. There are two methods for striking the arc: the scratch method and the tap method, Figure 11-5. The scratch method is recommended for begin- ning welders. The tap method is sometimes used after the welder gets some practice. To strike an arc using the scratch method, scratch the tip of the electrode over the work much like you would strike a match. As the arc starts, hold a slightly longer than normal arc until the base metal is heated enough to form a proper size pool of molten metal. Keep the electrode moving or it will “freeze,” or stick to the work. Figure 11-3. Use two hands to grasp the electrode holder whenever possible. Use a comfortable grip else your hand(s) will tire rapidly. Goodheart-Willcox Publisher Electrode travel Workpiece Travel Angle 90° 0° Workpiece Workpiece Work Angle 15°–20° 90° Figure 11-4. Electrode position and angles when running a fl at weld. Goodheart-Willcox Publisher