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8. Digital Voltmeter - This meter displays welding
voltage, as measured on the output studs of the
Square Wave TIG 275. After welding is complete,
the meter displays the welding voltage corre-
sponding to the peak welding current and displays
this value for approximately 5 seconds.
9. Thermal Protection Light - A yellow light which
only lights when an over temperature situation
occurs. See the
Maintenance Section
for more
information on thermostatic protection.
10. Power Switch - Controls the input power to the
Square Wave TIG 275.
11. Polarity Switch - Selects DC+, AC or DC- welding
polarity without reconnecting leads. DO NOT
SWITCH WHILE WELDING.
12. Twist Mate Electrode and
13. Work Connections - Easy to connect electrode
and work connections. This style Electrode
Connection makes the gas and current connec-
tions for the TIG torch at the same time. (Adapter
plugs are provided with the machine.)
14. Remote Receptacle - For Amptrol, Arc Start
Switch or Robotic Interface connection.
15. Optional Water Solenoid Connections - Easy to
install this optional feature which allows for water
flow control for water cooled torches.
WELDING OPERATION
TIG WELDING
Familiarize yourself with the Controls and Settings
Section before attempting operation of the Square
Wave TIG 275.
TIG WELDING GUIDELINES
TIG welding can be done in either the TIG 2-Step or
the TIG 4-Step Weld Mode. TIG 2-Step is typically
used with Hand or Foot Amptrols, with Remote Current
control. TIG 4-Step typically uses an Arc Start switch
and Local Current Control, because it provides a very
brief current upslope, and a .5 to 10 second adjustable
current downslope. TIG 4-Step also functions like a
trigger interlock, making it unnecessary to hold down
the Arc Start switch during a weld. This feature
requires that the remote control device in use must
have separate Arc Start and Output Control mecha-
nisms. Read the TIG Welding Sequence of Operation
sections for more details on 2-Step and 4-Step opera-
tion.
Recommended tungsten electrode sizes, stickouts,
currents, cup or nozzle sizes are shown in Table B.1.
SINCE WELDING APPLICATIONS CAN VARY, THIS
CHART IS INTENDED AS A GUIDE ONLY.
OPERATION
B-6 B-6
SQUARE WAVE TIG 275
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(1) When used with argon gas. The current ranges shown must be reduced when using argon/helium or
pure helium shielding gasses.
(2) Tungsten electrodes are classified as follows by the American Welding Society (AWS):
Pure . . . . . . . . . . . . . . . EWP
1% Thoriated . . . . . . . . EWTh-1
2% Thoriated . . . . . . . . EWTh-2
Though not yet recognized by the AWS, Ceriated Tungsten is now widely accepted as a substitute for
2% Thoriated Tungsten in AC and DC applications.
(3) DCEP is not commonly used in these sizes.
(4) TIG torch nozzle “sizes” are in multiples of 1/16ths of an inch:
#4 = 1/4 in. (6 mm)
#5 = 5/16 in. (8 mm)
#6 = 3/8 in. (10 mm)
#7 = 7/16 in. (11 mm)
#8 = 1/2 in. (12.5 mm)
#10 = 5/8 in. (16 mm)
(5)
TIG torch nozzles are typically made from alumina ceramic. Special applications may require lava nozzles,
which are less prone to breakage, but cannot withstand high temperatures and high duty cycles.
TABLE B.1 TYPICAL CURRENT RANGES FOR TUNGSTEN ELECTRODES
(2)
.010 (.25)
0.020 (.50)
0.040 (1.0)
1/16 (1.6)
3/32 (2.4)
1/8 (3.2)
5/32 (4.0)
3/16 (4.8)
1/4 (6.4)
2-15
5-20
15-80
70-150
150-250
250-400
400-500
500-750
750-1000
(3)
(3)
(3)
10-20
15-30
25-40
40-55
55-80
80-125
2-15
5-15
10-60
50-100
100-160
150-210
200-275
250-350
325-450
2-15
5-20
15-80
70-150
140-235
225-325
300-400
400-500
500-630
2-15
10-20
20-30
30-80
60-130
100-180
100-240
190-300
250-400
---
5-20
20-60
60-120
100-180
160-250
200-320
290-390
340-525
3-8 (2-4)
5-10 (3-5)
5-10 (3-5)
5-10 (3-5)
13-17 (6-8)
15-23 (7-11)
21-25 (10-12)
23-27 (11-13)
28-32 (13-15)
3-8 (2-4)
5-10 (3-5)
5-10 (3-5)
9-13 (4-6)
11-15 (5-7)
11-15 (5-7)
13-17 (6-8)
18-22 (8-10)
23-27(11-13)
#4, #5, #6
#5, #6
#6, #7, #8
#8, #10
1%, 2%
Thoriated
Tungsten
1%, 2%
Thoriated
Tungsten
Pure
Tungsten
1%, 2%
Thoriated
Tungsten
Zirconiated
Pure
Tungsten
1%, 2%
Thoriated
Tungsten
Zirconiated Aluminum
Stainless
Steel
Tungsten
Electrode
Diameter
in. (mm)
TIG Torch
Nozzle
Size
(4)
,
(5)
DCEN (
-
) DCEP (
+
)
Unbalanced Wave Balanced Wave
AC Approximate Argon
Gas Flow Rate
C.F.H. (1/min.)