59 Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. After completing this unit, you will be able to: List the two methods for striking the arc. Demonstrate the electrode position when running a fl at weld. Determine the necessary adjustments to the current, arc length, or speed by examining test welds. Key Terms arc length arc voltage scratch method tap method travel angle work angle The fi rst step in preparing to weld is to carefully check over the machine. Be sure all connections are clean and tight. Since the heat generated by the arc is determined by the amount of current (amperage) used, set the machine to the range recommended for the size of the electrode being used. If the manufacturer’s recommendations are not available, a good rule of thumb when using standard electrodes is to adjust the weld- ing machine to a current setting that is approxi- mately equal to the diameter of the electrode in thousandths of an inch. For example, a 1/8″ (0.125″ or 3 mm) diameter rod will operate at ± 125 amperes. (This may vary slightly for elec- trodes made by different manufacturers.) Warning: Warning: Put on your protective clothing before welding. Replace any items that are not up to standards. Remove all flammable materials and solvents from the welding area and put shields in place if others will be working in the immediate area. Unit 11 Preparing to Weld When you begin to weld, a few trail beads should be completed. Raise or lower the welding machine current setting until you get a satisfac- tory weld. A weld should not burn through, but it should have suffi cient penetration, Figure 11-1. Position the metal, securing it with clamps if needed. Attach the work (ground) clamp securely. Clamp the electrode in the electrode holder at about a 90° angle to the holder jaws, Figure 11-2. Keep the electrode and holder clear of the work area and turn on the machine. Grasp the electrode holder with a comfortable Amperage too low Amperage too high Correct penetration Figure 11-1. Weld characteristics. Goodheart-Willcox Publisher Electrode holder Electrode Figure 11-2. Electrode position in electrode holder for running a fl at weld. Goodheart-Willcox Publisher
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