making a fi llet weld in any position, a C-shaped weld pool is used. This shows that both pieces of metal are melting. This is similar to welding in the fl at position. The face of a completed fi llet weld should be fl at or slightly convex. See Figure 22-4. The weld should not sag down onto the lower piece. Sagging of weld metal can cause undercutting, underfi ll, or overlap. If any of these happen, change your torch angles and add the fi ller metal to the top edge of the weld pool. There should be no porosity. If there is, check that the shielding gas is set for the proper fl ow rate and that there are no leaks in the hoses, fi ttings, and connections. Porosity can also be caused by using too long an arc length. Exercise 22-1 Making a Horizontal Fillet Weld on a Lap Joint 1. Obtain two pieces of carbon steel measuring 1/8″ × 1 1/2″ × 6″ (3.2 mm × 40 mm × 150 mm). 2. Clean one long edge and one face on each piece. 3. Set up the welding machine for welding carbon steel. Use DCEN (DCSP) and 100A. Place the current switch in the remote position. Set the high-frequency start switch to on. 4. Set the shielding gas flow rate. Refer to Figure 20-8 for shielding gas flow rates. 5. Obtain a 2% thoria tungsten electrode 1/16″ (1.6 mm) in diameter. Grind the tip into a blunted point. Make sure the grind marks are lengthwise, as shown in Figure 20-16. 6. Select the correct size collet and collet body. Install these and the electrode in the torch. The electrode should extend 1/8″–3/16″ (3 mm–5 mm) beyond the end of the nozzle. 7. Obtain a 3/32″ diameter (2.4 mm) carbon steel welding rod. 8. Clamp the pieces to form a lap weld. Tack weld the pieces together at three places on each side of the joint. Place the workpiece in a horizontal position. Direction of weld 60°–75° 45° 15°–20° Goodheart-Willcox Publishing Figure 22-3. The suggested electrode and welding rod angles for gas tungsten arc welding a fillet weld in the horizontal position. The angles are the same for forehand and backhand welding. Goodheart-Willcox Publishing Figure 22-2. A student welder using GTAW to make a fillet weld on an inside corner joint in the horizontal position. Goodheart-Willcox Publishing Figure 22-4. An acceptable fillet weld. This weld was made on carbon steel. It has a flat bead, even ripples, and an even bead width. There is no apparent undercutting, sag, or overlap. Chapter 22 GTAW: Horizontal, Vertical, and Overhead Welding Positions 325 Copyright Goodheart-Willcox Co., Inc.