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B-10
OPERATION
B-10
10. With the torch held safely away from everything,
press the Arc Start Switch and set the gas flow
meter. Release the switch. The welder is now ready
for welding.
11. Position the tungsten electrode at the start of the
weld at a 65˚ to 75˚ angle with the horizontal so that
the electrode is approximately 1/8" (4 mm) above the
work piece. Press the Arc Start Switch. This opens
the gas and water valves to automatically purge air
from the hose and torch. After a 0.5 second preflow
time, the high frequency becomes available to strike
the arc.
12. Hold the Arc Start Switch down until an arc is estab-
lished. The arc will start at a low current value that is
equal to 25% +/- 10 % of the preset current estab-
lished in Step 5 or 5 Amps, whichever is greater.
13. Release the Arc Start Switch and the current will
ramp up to the preset maximum current in 0.5 sec-
onds and remain there indefinitely.
14. Press the Arc Start Switch a second time to initiate
the Down Slope time. The current will ramp down to
a crater fill level of 25% +/- 10 % of the preset current
or 5 Amps whichever is greater within the time set
with the Down Slope knob in Step 9.
15. Release the Arc Start Switch to stop the arc and start
the Post Flow timer. After the post flow time has
expired, the gas and optional water valves will close.
The make another weld, repeat steps 11 through 15.
HAND AND FOOT AMPTROL OPERATION
Both the Hand and Foot Amptrol work in a similar man-
ner. They are meant to be used for remote current con-
trol. The TIG 2-Step mode must be selected when
using an Amptrol for remote current control.
For simplicity, the following explanation will refer only to
"Amptrols", meaning both Foot and Hand models. The
term "minimum" refers to a Foot pedal in the "up" posi-
tion, as it would be with no foot pressure, or a Hand
Amptrol in the relaxed position, with no thumb pres-
sure. "Maximum" refers to a fully depressed Foot
Amptrol, or a fully extended Hand Amptrol.
The Amptrol is capable of controlling the output current
from 5 amps to the preset current on the output control
knob. For example, if the preset is at 200 amps, the
Amptrol, when depressed just past its minimum posi-
tion, will cause the Square Wave TIG 275 to weld at 5
amps. At the Amptrol's maximum position, the output
will be near 200 amps.
It is important to note that, for many applications, the
tungsten will not start an arc at only 5 amps. (Refer to
the TIG Welding Guidelines for recommended tungsten
currents.) To start an arc reliably, it is important to
depress the Amptrol far enough so that the machine
output current is near the tungsten operating range. In
the example above, a 3/32" tungsten may be used on
DC- to weld near 200 amps. To start the weld, the
operator may have to depress the Amptrol approxi-
mately 1/4 of the way down, or to nearly 50 amps, in
order to start the arc. Merely depressing the Amptrol to
its 5 amp minimum position will not start the arc.
ADVANCED TIG WELDING FEATURES
AC WAVE BALANCE AND AUTO BALANCE™
The AC Wave Balance feature is unique to the Square
Wave TIG 275. It is active only in AC TIG mode. It con-
trols the amount of positive and negative current in the
AC output.
The Square Wave TIG 275 allows the operator to select
Auto Balance™. This selection provides automatic
adjustment of the AC Wave Balance; it is suitable for
most welding conditions. Auto Balance™ gives the
ideal amount of cleaning and penetration, based on the
welding current output.
Manual adjustment of the AC Wave Balance is also
possible. Manual Balance settings vary from 0 (maxi-
mum cleaning) to 10 (maximum penetration). A setting
of 3 yields a balanced output (equal amounts of clean-
ing and penetration). Use the following as a guide
when setting the Balance manually:
BALANCED (3): The amounts of positive and nega-
tive are the same.
CLEANING (0 to 2): Provides more positive current
than negative current. Since the positive cur-
rent produces the "cleaning" or oxide removal
on aluminum, this setting is used for welding on
heavily oxidized aluminum.
PENETRATION (4 to 10): Provides more negative cur-
rent than positive. The arc plasma will be more
concentrated and more easily directed to
where the heat is needed. Higher penetration
settings allow a given size of tungsten to carry
more current.
CAUTION: Use only the amount of cleaning required
because the greater amount of positive current will
heat the tungsten more and possibly cause it to melt or
"spit". Also, the arc is usually more flared and less sta-
ble with more cleaning current.
In general, use just enough "cleaning" to remove
oxides and to give good wetting of the puddle.
SQUARE WAVE TIG 275