Tweco 250i Transmig Inverter - Manual (Page 53)

INSTALLATION/SETUP TRANSMIG 250i
Manual 0-5187 3-35 INSTALLATION/SETUP
3.25 Set-up for LIFT TIG (GTAW) Welding
!
WARNING
Before any welding is to begin, be sure to wear all appropriate and recommended safety equipment.
NOTE
The following steps will assume that you have already set up the proper shielding gas as outlined in Sub
Section 3.22.
NOTE
The following set up is known as Straight Polarity or DC Electrode Negative. This is commonly used for
DC TIG welding on most materials such as steel and stainless steel.
1. Switch the ON/OFF Switch (located on the rear panel) to OFF.
2. Connect the work lead cable to the positive output terminal, and the TIG Torch cable to the negative output
terminal. Refer to Figure 3-32.
3. Connect the gas line/hose to the proper shielding gas source. Refer to Figure 3-32.
4. Be sure the gas valve on the TIG Torch is closed, and slowly open the Argon Cylinder Valve to the fully open
position.
5. Connect the work lead clamp to your work piece.
6. The tungsten must be ground to a blunt point (similar to a pencil) in order to achieve optimum welding results.
See illustration. It is critical to grind the tungsten electrode in the direction the grinding wheel is turning. Grind
at a 30 degree angle and never to a sharp point.
A-00503_AB
Electrode
2 to 2-1/2 Times
Electrode Diameter
Figure 3-31: Electrode sharpening
7. Install the tungsten with approximately 3.2mm to 6.4mm sticking out from the gas cup, ensuring you have
correct sized collet.
8. Tighten the back cap.
9. Turn the switch to the “ON” position. The power L.E.D. light should illuminate.
10. Set the welding process to LIFT TIG.
11. Set the Weld Current Control Knob to the desired amperage.