Lincoln Electric POWER-ARC 4000 SVM103-A Service Manual page 28

B-13
THE CORRECT ARC LENGTH
The arc length is the distance from the tip of the elec-
trode core wire to the base metal.
Once you've established the arc, maintaining the cor-
rect arc length is critical. It should be short, 1/16 to
1/8 inch (3.2 mm) long. As the electrode burns off, you
must continue to feed it into the work to keep the arc
length correct.
The easiest way to tell if the arc length is correct is to
listen to it. A nice, short arc has a distinctive "crack-
ling" sound, like eggs frying in a pan. A long, incor-
rect, arc has a hollow, blowing or hissing sound.
THE CORRECT WELDING SPEED
To know whether your welding speed is correct, you
must watch the puddle of molten metal behind the arc.
DO NOT WATCH THE ARC ITSELF. The appearance
of the puddle and the ridge where it solidifies tells the
tale. The ridge should be approximately 3/8 inch (9.5
mm) behind the electrode. See Figure B.6.
POWER-ARC 4000
OPERATION
FIGURE B.6 – MOLTEN METAL PUDDLE
AND CORRECT WELD SPEED
1. ELECTRODE
2. ARC
3. RIDGE OF MOLTEN METAL
4. WELD PUDDLE
Most beginners tend to weld too fast, which gives a
thin, uneven, "wormy" looking bead. They are not
watching the molten metal puddle.
NOTE: When welding on thin plate, you will find that
you have to increase welding speed.
heavy plate, you will have to go more slowly to
ensure fusion and penetration.
The key to developing welding skill is PRACTICE. No
one can learn to weld just by reading about it. If you
are an inexperienced welder, the information here will
help you understand some basic welding principles
you should know before you use your POWER-ARC
4000 for stick welding. For more detailed information,
order a copy of the book New Lessons in Arc Welding,
available from the Book Division of Lincoln Electric.
See the form located at the back of this manual for
ordering information!
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