Matco Tools MP200DVILCD Owner's Manual page 35

ii. The arc will be difficult to maintain.
c. When the rod is too large:
i. The arc will burn through light metals.
ii. The bead will undercut the work.
iii. The bead will be flat and porous.
iv. The rod may be freeze or stick to the work piece.
Note: The rate of travel over the work also affects the weld. To ensure proper penetration and enough deposit
of rod, the arc must be moved slowly and evenly along the weld seam.
5. SETTING THE AMPERAGE CONTROL
The welder has an infinite current control. It is capable of welding with electrodes up to 3/32"
diameter. It is best to practice your welds on scrap metals which match the metals you intend to
work with to determine correct setting for your job. The electrode type and the thickness of the
work piece metal determine the amount of heat needed in the welding process. Heavier and
thicker metals require more voltage (amperage), whereas lighter and thinner metals require less
voltage (amperage). Consult the welding electrode packaging for recommended welding
amperage range.
6. WELDING TECHNIQUES
The best way to teach yourself how to weld is with short periods of practice at regular intervals.
All practice welds should be done on scrap metal that can be discarded. Do not attempt to make
any repairs on valuable equipment until you have satisfied yourself that your practice welds are
of good appearance and free of slag or gas inclusions.
Holding the electrode
a.
The best way to grip the electrode holder is the way that feels most comfortable to you.
Position the electrode to the work piece when striking the initial arc it may be necessary
to hold the electrode perpendicular to the work piece. Once the arc is started the angle
of the electrode in relation to the work piece should be between 10 and 30 degrees. This
will allow for good penetration, with minimal spatter.
EXPOSURE TO A WELDING ARC IS EXTREMELY HARMFUL TO THE EYES AND SKIN!
Prolonged exposure to the welding arc can cause blindness and burns. Never strike an arc
or begin welding until you are adequately protected. Wear flame-proof welding gloves, a
heavy long sleeved shirt, trousers without cuffs, high topped shoes, and an ANSI approved
welding helmet.
ELECTRIC SHOCK CAN CAUSE INJURY OR DEATH! To prevent ELECTRIC SHOCK, do not
perform any welding while standing, kneeling, or lying directly on the grounded workpiece.
b. Striking the arc
Scratch the work piece with the end of electrode to start arc and then raise it quickly
about 1/8 inch gap between the rod and the work piece, see following picture:
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